No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Does land irrigation actually reduce foraging habitat for breeding lesser kestrels? The role of crop types
Abstract
The lesser kestrel is a Globally Threatened Species which large decline has been related to recent agricultural changes in Euro-pean pseudo-steppes. Irrigation is considered as one of the major threats for this and other steppe birds, but the actual effects of irrigation on foraging habitat selection have been scarcely examined. We studied the selection of traditional dry cereal farming and irrigated habitats by foraging lesser kestrels during the breeding cycle, paying especial attention to possible differences among crop types. Field margins were the scarcest but the most positively selected habitat, and different stages of cereals cultivated follow-ing traditional practices were selected depending on the breeding and agriculture cycles. Effects of irrigation were dual. While irri-gated maize and other crop types were avoided, alfalfa was used in proportion to its availability and later highly selected after harvesting. Moreover, field margins in irrigated land were selected in a similar way than in traditional dry farmland. Therefore, although maintaining low-intensity farming is still the main recommendation for this species, new management options arise when social pressure makes irrigation unavoidable. Further agri-environmental schemes in these circumstances should thus promote cul-tivation of alfalfa with a low input of biocides while avoiding maize, together with increasing field margins, to make compatible irrigation with lesser kestrel conservation.
... Alternative crops have been suggested to be capable for sustaining high levels of biodiversity (Ursúa, Serrano, & Tella, 2005). In Spain, a conservation plan aimed at restoring little bustard (Tetrax tetrax) populations was based on an AES in alfalfa (Medicago sativa) crop areas. ...
... Such a conservation plan well increased population productivity, which was mainly associated with bustard nesting in AES fields (Bretagnolle et al., 2011). Alfalfa was also highly selected by lesser kestrels after harvest, and was considered to be a useful alternative when economic pressures made irrigation unavoidable in dry-lands (Ursúa et al., 2005). ...
... Alfalfa in Spain (Ursúa et al., 2005) and artichoke in South Sicily are among the few demonstrated cases of alternative cultivation that potentially offer a win-win scenario, as they provide an optimal trade-off between biodiversity and economic sustainability for farmers. ...
... Specific studies showed that in different areas of Spain, lesser kestrels were less abundant and had lower food availability in intensive cropping areas and consequently needed larger home ranges but still had lower breeding success than in tra-ditionally farmed areas (Donázar et al. 1993;Tella et al. 1998;De Frutos et al. 2015). Radio tracking and focal monitoring proved that lesser kestrels indeed selected field margins and traditionally farmed fields and avoided hunting in intensive irrigated crops except when the crop was alfalfa (Tella et al. 1998;Ursúa et al. 2005). In the Guadalquivir Valley in southern Spain, food shortage was so marked in those intensively farmed areas that large fledgling mortalities were detected in some breeding colonies (Hiraldo et al. 1996). ...
... The identification of the factors that allow those eagle species to successfully breed in such altered environments would certainly help to understand what limits birds of prey in agricultural landscapes. In any case, these studies, and similar ones with other species dealing well in intensified environments (Ursúa et al. 2005;Cardador et al. 2011;Buij et al. 2013), indicate that not all intensive productive systems are the same. In general, it seems that to maintain certain habitat heterogeneity, with hedgerows and natural field margins, and adequate grazing pressures is positive for most raptors using agroecosystems (e.g., Tella et al. 1998;Ursúa et al. 2005;Amar and Repath 2005;Torre et al. 2007;Butet et al. 2010). ...
... In any case, these studies, and similar ones with other species dealing well in intensified environments (Ursúa et al. 2005;Cardador et al. 2011;Buij et al. 2013), indicate that not all intensive productive systems are the same. In general, it seems that to maintain certain habitat heterogeneity, with hedgerows and natural field margins, and adequate grazing pressures is positive for most raptors using agroecosystems (e.g., Tella et al. 1998;Ursúa et al. 2005;Amar and Repath 2005;Torre et al. 2007;Butet et al. 2010). However, particular studies should be carried out to assess which factors of productive intensification are leading negative trends on each particular species or community so that specific managing options may be taken on each case. ...
The introduction of agricultural activity (including livestock farming) in natural environments affects all the natural processes occurring there, from individual behavior and population dynamics to communities’ composition and flows of matter and energy, and from local to landscape scales.
... Cotton fields are poor habitats in prey because of the high agro-chemical inputs that make them toxic to invertebrate fauna [59]. Ursua et al. [60] found that field margins are important feeding habitats for breeding lesser kestrels in areas surrounded by irrigated farmland. However, selection of field margins as preferred foraging habitats for lesser kestrels was not documented in this study, probably due to the time of the year field work was conducted (see below). ...
... However, selection of field margins as preferred foraging habitats for lesser kestrels was not documented in this study, probably due to the time of the year field work was conducted (see below). Yet, field margins are widely recognised as a significant foraging habitat for the species, supporting their preferred prey [12,13,19,57,60]. ...
... Foraging lesser kestrel abundance was negatively associated with scrubland and woodland. Researcher argue that in habitats with dense vegetation cover (i.e., scrubland, woodland, tree plantations and olive orchards), prey is likely to be less accessible or scarce [12] and birds avoid them [13,14,17,20,56,60]. Besides, foraging range has been found to be larger in areas with inappropriate habitats, such as irrigated fields, forest and scrubland, compared to areas with non-intensive cultivations and birds make longer foraging trips to search for food [13,18,21]. ...
The European Union (EU) Wild Birds Directive recognises that the most serious threats to wild birds’ conservation in
Europe are habitat loss and degradation, and hence, habitats of threatened and migratory species must be protected with the
establishment of the network of the special protection areas (SPAs) for migratory and endangered bird species in the EU member
states. The major European population of the lesser kestrel Falco naumanni, a migratory falcon listed in Annex I of the Birds
Directive, occurs in low-input farming systems in the Mediterranean basin, including Greece. The aim of this study was to identify
foraging habitats of lesser kestrels and relate them to the delimited SPAs in the agro-ecosystems of Greece, where the stronghold of
the species population for Greece occurs. Foraging habitat preferences were assessed using Poisson regression models (PRMs). SPAs
were examined on whether they can effectively protect foraging habitats for breeding lesser kestrels in the study area. Foraging lesser
kestrel abundance was positively associated with grasslands and non-irrigated land (dry cereals), and negatively associated with
irrigated land (wet cotton), scrubland and woodland. Electricity facilities were used as foraging perches by lesser kestrels. The
current SPAs cover a small percentage of the species’ foraging sites and cannot be considered coherent enough to support and protect
the foraging habitats of lesser kestrels and other priority species in the agro-ecosystems of the study area. Proposals for effective
conservation of low-input farming systems, supporting priority species, are also presented.
... Forest habitat can be increased with the encouragement of the agri-environmental schemes, promoted by the Common Agriculture Policy to farmers to forest their farms (MAPA, 2007). Suggestions for avoiding land abandonment and afforestation have been highly recommended in breeding areas of lesser kestrel (Ursúa, Serrano & Tella, 2005). ...
... Therefore, irrigation may affect negatively to lesser kestrel numbers in the study area. Although lesser kestrels can select irrigated crops once they have been harvested (Ursúa et al., 2005), in general they are avoided during the winter (Tella & Forero, 2000), breeding period and summer (this study). In our area, maize accounts for almost 90% of the crops once the area is irrigated and remains unharvested throughout summer hampering use by lesser kestrel. ...
... pers.), but if these birds are flexible in their dispersing behaviours to find other suitable premigratory areas is still unknown. Therefore, given that this irrigation plan is unavoidable and applying the precautionary principle, special agri-environmental measures should be implemented around the lesser kestrel roosts affected (see Ursúa et al., 2005). ...
... The most-studied Lesser Kestrel populations are in Western Europe (Añigo & Barov 2010). Most research has been conducted in Spain (Donázar et al. 1993, Tella et al. 1996, Bustamante 1997, Ursúa et al. 2005, De Frutos et al. 2010, Galabuig et al. 2011, the country that holds the largest European population (Atienza & Tella 2004). Other studies have been carried out in Italy (Sarà 2010, Sarà et al. 2012, Di Maggio et al. 2013, Portugal (Catry et al. 2004, Catry et al. 2011, 2012 and Greece (Vlachos et al. 2003(Vlachos et al. , 2004. ...
... Sidi Kacem and Souk Larbaâ del Gharb colonies are adjacent to irrigated agricultural areas mainly dominated by cereal crops and mono-specific stands with fruit trees. This man-made agricultural landscape is generally not favourable for Lesser Kestrels due to agricultural intensification and irrigation (Fernández Ales et al. 1992, Bustamante 1997, Tella & Forero 2000, Franco et al. 2005, Ursúa et al. 2005. Even so, these two colonies increased as well and this may be because the Gharb irrigated area also provides both the availability of nest-sites (inaccessible cliffs and barns) and the combined presence of dry cereal stubbles and fallows which have been identified as important in Spain , De Frutos et al. 2010). ...
... Sarà (2010), in studying the effects of land-use changes on the abundance of Lesser Kestrels, noted the significance of artichoke (Cynara spp.) cultivations as suitable food resources. Similarly, in Los Monegros (Spain), Ursúa et al. (2005) reported the role of field margins of irrigated areas as foraging habitats. ...
The number of Lesser Kestrel Falco naumanni breeding pairs in Morocco has varied significantly and positively over thirteen years (1998–2010), between six colonies and over the 13-year period at each colony. The mean growth rate was λ=1.13±0.02. This positive trend is consistent with the current Least Concern conservation status of the species in the IUCN Red List.
... Several studies show that changes in agriculture productive systems have been linked to a decrease in food resources for raptors 15,18,[62][63][64] . However, the persistence of implanted pastures and grassland for extensive cattle, as well as the maintenance of grassland in the shoulders of roads and railways, may maintain high local food availability and probably easy access to prey for raptor species like the American kestrel 11,54,[65][66][67] . ...
... The persistence of these remnants of native vegetation and pastures may be masking the negative effects of agricultural intensification in our study area and be used by American kestrels to successfully occupy those fields. Simple management practices carried out in other agroecosystems such as maintaining untilled field margins and hedgerows seem positive for raptors 10,66 . Similar practices should be encouraged in our study area to increase the kestrel's breeding performance. ...
Land-use changes due to agricultural intensification and climatic factors can affect avian reproduction. We use a top predator of agroecosystems, the American kestrel (Falco sparverius) breeding in nest boxes in Central Argentina as a study subject to identify if these two drivers interact to affect birds breeding. We analyzed their breeding performance across a gradient of agricultural intensification from native forest, traditional farmland to intensive farmland. The surface devoted to soybean was used as a proxy of agriculture intensification; however, it did not affect the breeding performance of American kestrels. Even though the presence of pastures was important to determine the probability of breeding successfully. Climatic variables had strong effects on the species breeding timing, on the number of nestlings raised by breeding pairs and on the probability of those pairs to breed successfully (raising at least one fledgling). Our results highlight the relevance of pastures and grasslands for American kestrel reproduction. These environments are the most affected by land-use change to intensive agriculture, being transformed into fully agricultural lands mostly devoted to soybean production. Therefore, future expansion of intensive agriculture may negatively affect the average reproductive parameters of American Kestrels, at least at a regional scale. Further research will be needed to disentangle the mechanisms by which weather variables affect kestrel breeding parameters.
... As birds do not have territorial restrictions, they can fly long distances to forage when there are no suitable habitats close to colonies or food is insufficient García et al. 2006;Bonal & Aparicio 2008;Catry et al. 2013). Other studies show, however, that birds are negatively associated with irrigated crops such as maize (Ursúa et al. 2005;De Frutos & Olea 2008;De Frutos et al. 2010;De Frutos et al. 2015). ...
... Selection of cotton could also be explained by birds association with linear habitat features, such as field margins, that is, important elements of HNVf, interspersed in cotton fields used for foraging (pers.obs., Ursúa et al. 2005). Field margins were not included in model development, because they could not be detected by the image classification analysis because of the coarseness of the thematic map resolution (30 m pixel). ...
Agricultural areas, such as cereal cultivations, that support species of European and/or national conservation concern are considered as ‘High Nature Value’ farmlands (HNVf) and are very important for the preservation of biodiversity in Europe. The lesser kestrel Falco naumanni is a migratory falcon breeding largely in the HNVf of the Mediterranean basin. The main cause of its decline in Europe has been habitat loss and degradation as a result of agricultural intensification driven largely by the EU Common Agricultural Policies (CAP). In Greece, its population dropped by about 50% since the 1970s and its preferred habitats have shrunk. The aim of this study was to assess habitat preferences of breeding Lesser Kestrels in agro-ecosystems of Greece and relate these habitats to HNVf for conservation purposes. The study area is located in the plain of Thessaly, Central Greece, holding the main lesser kestrel breeding populations in the country, where dry cereal crops have been significantly depleted over the past decades. Species distribution models were developed with generalised additive models for the analyses. Predicted probability of lesser kestrel occurrence was found to be positively associated with farmed landscapes of dry cereal cultivations. Other important predictors were cultivated irrigated farmland and landscape heterogeneity. Main results of the statistical models agree with the findings of other habitatbased studies that highlight the importance of low-input farming systems, that is, HNVf, for safeguarding vital Lesser Kestrels habitats in their breeding grounds in the Mediterranean. A key conservation priority for conserving species dependant on HNVf is the maintenance of those low-input farming systems and the implementation of a greener CAP that would promote environmental-friendly farming practices to preserve and enhance biodiversity in the agro-ecosystems of Europe.
... To assess habitat selection we used the Savage selectivity index (e.g. Tella and Forero, 2000;Ursúa et al., 2005;Catry et al., 2013): wi = Ui/pi, where Ui is the proportion of observations recorded in a given habitat and pi is the proportion of that habitat related to the total habitat available. This index varies from 0 (maximum negative selection) to infinity (maximum positive selection), 1 indicating no selection (Manly et al., 1993). ...
... However, maize fields offered low small mammal abundance (Alves, 2013), failing to provide food for harriers. These results agree with previous findings showing that although farming intensification is generally a major threat for open-habitat bird species (Benton et al., 2003), some intensive agricultural lands are still able to provide adequate foraging conditions for some species -such as the marsh harrier -at least outside the sensitive breeding season, and if food availability is not compromised (Ursúa et al., 2005). Moreover, field observations indicated that human disturbance, resulting from agricultural machinery, was greater and more continuous in maize than in rice fields, which may also have contributed to maize avoidance. ...
Studying various aspects of the biology of a species of conservation concern allows us
to improve our understanding of, for example, how the particularities of the landscape matrix influence
its occurrence. The Lower vouga Lagoon in central-western Portugal offers an unusual diversity of
natural and humanised biotopes in an agricultural-wetland complex mosaic. This study aimed to identify
the factors that may influence the occurrence and abundance of a diurnal raptor, the marsh harrier Circus
aeruginosus, in this kind of landscape. The marsh harrier is a top predator that is considered as an
umbrella species, i.e. one whose conservation may also help preserve and promote biodiversity in general
in its community. This study provides potentially valuable information on management and conservation
strategies in both natural and agricultural areas. We found that natural habitats, such as reedbeds, are a
key habitat for this predator, providing shelter, food and suitable nesting sites. Despite the general
negative effect of human pressure on the occurrence of marsh harriers, the species seems to tolerate and
even benefit from humanised environments, such as rice fields, which constituted the preferred foraging
habitat during the non-breeding period. Nevertheless, the degree of disturbance should be carefully
considered, since road density and agricultural machinery negatively influenced the presence of the
species in the landscape, particularly during the breeding period. The preservation of the distinctive
features of the studied mosaic is very important. It is also necessary to establish a conservation
programme involving the local human community.
... Vegetation structure is dramatically transformed and the tall vegetation of cereal crops is replaced by the short vegetation landscape of stubble fields, likely impacting prey availability and foraging decisions of other insectivorous species (Delgado & Moreira 2000, Palacín et al. 2011. Cereal fields are either selected (Donázar et al. 1993, Tella et al. 1998 or avoided (Bonal & Aparício 2001, Cordeiro et al. 2005, Ursúa et al. 2005, García et al. 2006 by Lesser Kestrels while cereal stubbles, often not included in habitat selection analyses (Donázar et al. 1993, García et al. 2006, seem to be a preferred habitat for foraging individuals (Bonal & Aparício 2001, Franco et al. 2004, Cordeiro et al. 2005. Nonetheless, these studies did not consider the harvest period (but see Catry et al. 2012) and the potential decay in the quality of stubble fields within the season. ...
... Similar impacts were described for Montagu's Harriers Circus pygargus (Pilon 2005). Within the chick-rearing period, cereal crops were either used in the proportion of its availability (Ursúa et al. 2005) or avoided (Bonal & Aparício 2001, García et al. 2006) by foraging Lesser Kestrels depending on the colony and period. Rodríguez et al. (2013) pointed out that contradictory results (Donázar et al. 1993 andTella et al. 1998 found a positive selection of cereal crops) might be a consequence of differences in the vegetation structure which could be more important than habitat type in the process of patch selection. ...
Capsule Cereal harvesting creates high-quality but ephemeral foraging habitats for invertebrate predators.
Aims To investigate how cereal harvesting affects foraging decisions and hunting success of Lesser Kestrels.
Methods Habitat selection in response to changing availability of cereal fields (as patches being harvested
are turned into stubble) was assessed by transects around colonies to count foraging birds. Focal
observations of foraging kestrels were performed to assess hunting success and intake rate before and
after harvesting. We performed transects to count Orthoptera to evaluate the impact of cereal cutting on
prey abundance.
Results Harvesting impacted prey accessibility due to a temporary flush of prey, which resulted in a
significant reduction in foraging time and an increase in the intake rate of kestrels. Accordingly, patches
being harvested became the most preferred habitat. Nonetheless, harvesting likely caused high
orthopteran mortality and dispersal leading to a gradual decline in prey abundance in stubbles. Lower
prey abundance increased foraging time and reduced intake rate, and stubbles became avoided by
foraging individuals.
Conclusion Although harvesting significantly increases foraging opportunities for Lesser Kestrels through
intake rate maximization, patches being harvested represent an ephemeral high-quality habitat and its
benefits are relatively short-lived as cereals are converted into low-quality stubbles.
... Our study calls for a need to improve land management strategies compatible with the conservation of Kestrels and other birds breeding in agricultural landscapes, such as the Lesser Kestrel (Ursua et al. 2005, Catry et al. 2012. Although the IUCN classified the species as of Least Concern, Eurasian Kestrel populations have shown a steady decline in most parts of Europe because of agricultural intensification (Snow & Perrins 1998). ...
... Results of our study also have implications for other birds of prey. For example, Ursua et al. (2005) showed that breeding Lesser Kestrels avoided irrigated maize and other crop types, while selecting for temporary grasslands of alfalfa. Similarly, another study, applying a behaviourbased model to assess how farmland management influences foraging decisions of Lesser Kestrels, showed that the conservation of Lesser Kestrel populations largely depends on allocating large fields of fallows around the colonies (Catry et al. 2012). ...
There are serious concerns about the environmental and ecological degradation caused by modern agriculture and its impact on animal populations. There is therefore a need to assess the reproductive performance of free-living animals in agricultural landscapes. We undertook a 4-year study on the reproductive biology of Eurasian Kestrel Falco tinnunculus in the Parma district of Italy. Kestrels breeding in areas of intensive agriculture delayed egg-laying and their offspring were in poorer condition compared with those breeding in areas of temporary or permanent grasslands. However, egg volume and fledging success were similar among sites. The availability of temporary and permanent grasslands may limit the negative impacts of intensive agriculture on the breeding activity of Kestrels.
... In lesser kestrels, which traditionally live in association with human activities, the management of landscape around colonies is of great importance for their conservation Bustamante 1997;Tella et al. 1998;De Frutos et al. 2010). Once agricultural landscapes covered 60% of land in Europe (Pain and Dixon 1997), but agricultural policies and land use changes affect lesser kestrel populations by affecting their prey types and availability (Tella et al. 1998;Ursúa et al. 2005;Catry et al. 2012). Hence, knowledge of habitat use by local populations of this bird in Europe is of prime importance for its conservation. ...
... Journal of Natural History 9 (Ursúa et al. 2005). Falcons cue on human-related disturbances in managed grassland habitat (Toland 1987) and probably use a combination of habitat features as cues to select suitable hunting sites (Bakaloudis 2010;De Frutos et al. 2010). ...
Home range size and foraging habitat use in breeding lesser kestrels (Falco naumanni), a bird species of conservation concern, were investigated during the breeding season of the species in 2008 in an intensively cultivated area of central Greece, using radio-tracking. Grasshopper (the main prey) densities were measured at the most important habitats (cotton, cereals, grasslands and margins). Home ranges were not significantly different between sexes either as overall means or during incubation and nestling periods. Movements of both sexes were non-random during incubation but random during the nestling period. Habitats used by males during incubation ranked as: margins > other > cotton > corn > cereals and during nestling period as: cereals > margins > grasslands > corn > cotton. Female habitat use greatly differed ranking as cereals > cotton > grasslands during incubation and as grassland > cotton > corn > cereals > margins during nestling period. Female habitat use seemed to be in disagreement with the conditions generally favouring prey availability, probably for reasons associated with low and uniform distribution of grasshopper densities over the habitats
... This peculiar habitat preference has been suggested as being related to prey availability (Tella et al., 1998) and the reduction in the extent of their foraging habitat explains the decline of the lesser kestrel population better than a reduction in nest availability (Forero et al., 1996) or pollution from pesticides (Negro et al., 1993). Consequently, agricultural intensification due to irrigation schemes coupled with the abandonment of traditional agriculture and the afforestation of marginal land have strong detrimental effects on this species (Tella and Forero, 2000;Brotons et al., 2004;Ursua et al., 2005). Results obtained in studies conducted in cereal steppes of Sicily are similar; lesser kestrels are affected by the reduction of arable land around their colonies and by the increasing prevalence of vineyards. ...
... Following the harvest, artichoke fields are abandoned and harbour rich pest populations of Dynastide beetles (Pentodon bidens) and Savi's voles (Microtus savii), which are a substantial part of the lesser kestrel diet at the time when they settle at their colonies (author's unpublished data). Ursua et al. (2005) reported that the relative weight of crop types provides an indication of how intensive cultivation (alfalfa fields in their case) can represent suitable foraging areas for lesser kestrels. However, the use of chemicals and other pollutants (PVC) in artichoke farming is very high (Prato and Signorello, 2009;ISTAT, 2010), and this might produce negative effects in some places, interacting with the decrease of arable fields. ...
Monitoring of lesser kestrels Falco naumanni is necessary to promote conservation of this vulnerable species. To this end, 35 colonies of this species located in the NNW and SE of Sicily were monitored from 2003 to 2009. Counts of the active colonies and resident pairs were modelled by loglinear Poisson regressions to assess population trends over the study period. Afterwards, a GLM with an analysis of covariance design and a backward removal stepwise regression was performed to relate the observed trend to local- or global-scale climatic variation and to local land-use changes. Colony counts provided a better fit to the loglinear models than pair counts. Loglinear models separated the increasing trend of the SE population breeding in buildings and living in a flat semi-arid area from the non-increasing trend of the NNW population, which breeds on cliffs at higher altitudes and lives in a warm temperate area. The effect of the covariate 'population' suggests a considerable role for the geographic range in modelling the abundance of colonies, which appears to also be relevant when it interacts with climatic and land-use changes. Land-use variables have the greatest weight in predicting the abundance of lesser kestrel colonies. The transformation of arable land negatively correlates with the abundance of colonies in both areas, and the intensification of woody crop cultivation (vines, hops and orchards) is likely to be the major cause of the observed population trend in NNW Sicily. Warm, dry climatic conditions in March and April, during the onset of reproduction, negatively affect lesser kestrels and the largescale climate significantly interacts with land uses. Conservation efforts aimed at the management of suitable habitat conditions of the SE population and the recovery of the NNW population must incorporate the effects of global warming in addition to land-use practices to allow for more effective actions to be taken.
... Rather, the substantiation of these threats often comes from indirect evidence. For example, studies on habitat selection generally agree on habitat preferences for foraging , Bustamante 1997, Parr et al. 1997, Tella et al. 1998, Ursúa et al. 2005, Rodríguez et al. 2006, cf. Catry et al. 2012 or for colony foundation (Calabuig et al. 2010), but it is necessary to investigate relationships between the availability of favourable habitat and colony sizes, or to examine whether current colonies are constrained by the extent of favourable habitat to demonstrate explicitly that this threat is a direct cause of population decline. ...
Lesser kestrel (Falco naumanni, Fleischer, 1818) populations have been one of the best monitored bird populations in Spain over the last 70 years. These populations suffered a sharp decline between the 1950s and 1990s. Since then, periodic censuses showed a population increase that lasted until 2010s. In those years, numerous projects for the recovery of the species were also initiated (some EU LIFE Projects, among others), which have continued to the present day. However, despite conservation efforts, the Spanish Lesser Kestrel population, which include about 40% of the European breeding population, has declined at a rate of 6% per year since 2012. In this paper, we analysed changes in habitat and population size in 12 colonies located in La Mancha between 2003 and 2021 in order to identify possible causes of the current decline. This colonial species breeds in old buildings and roof area (a proxy of the house size) was the predictor that best accounted for the number of pairs in a colony in a given year. In addition, the extent of herbaceous crops (related with prey availability) explained a similar amount of colony size variance in 2021, while in 2003, the availability of large Orthoptera itself had a significant effect but a much lower effect size. The number of nest boxes affected positively the number of breeding pairs in 2021, but it explained only 1% of the variance. The decline of Lesser Kestrel population between 2003 and 2021 was largely explained by the decrease of the density of large orthopterans, their main prey. The model with minimum AICc value also included a positive association with changes in roof area and a negative association with rabbit density (possibly through a hyperpredation phenomenon). Other top models (i.e. ΔAICc ≤ 2 units) also showed negative effects of the loss of favourable land uses (pasture lands and herbaceous crops) on colony size, probably because it had caused a reduction in the availability of large Orthoptera. These changes in land use occurred less likely in areas protected by the Natura 2000 network and, therefore, it may have contributed to the conservation of the Lesser Kestrel population. However, other conservation measures such as the installation of nest boxes were not as efficient as expected.
... For example, the sage grouse (Centrocercus urophasianus) in North America uses alfalfa crops to rear their chicks due to the high abundance of insects (Connelly et al., 2000). Similar results were found by Ursúa et al. (2005) in irrigated alfalfas; their results showed that lesser kestrels (Falco naumanni) used this crop after harvest as foraging habitat during the chick-rearing period. Similarly, the link between alfalfas and vole abundance (see also below) implies that alfalfas are a good foraging habitat for many vole-eating birds such as Montagu's harrier (Circus pygargus) or marsh harriers (C. ...
The agriculture intensification required to provide enough food commodities for humans has negative impacts on the environment. To reduce these drawbacks Agri-Environmental Schemes (AES) have been implemented in Europe since the last decade of the twentieth century. One of the measures included in these schemes was the introduction of alfalfas in crop rotation systems. In order to evaluate their suitability as an AES, we synthesize knowledge on the agronomical benefits of alfalfa cultivations, as well as on the relationships of alfalfa crops with biodiversity at three taxonomic levels: vascular plants, arthropods, and vertebrates. Based on the articles reviewed, alfalfas can help restoring native grassland communities due to the nutrient enrichment they provide. Moreover, this legume crop usually ensures food resources not only for invertebrates, but also for vertebrates. Alfalfas tend to harbour a stable arthropod community that benefits surrounding crops by improving ecological processes (pollination, pest predation) and reducing the need to use agrochemicals. At the same time, arthropod abundance attracts vertebrates, especially birds, which supports the role of alfalfa as a conservation tool to favour endangered farmland birds. Additionally, alfalfa crops may function as a reservoir habitat for voles, which are a preferred food resource for farmland-foraging raptors, many of them endangered. On the other hand, birds nesting in alfalfa crops may suffer higher nest destruction rates due to frequent cuts, and voles using alfalfa crops as reservoir may also create agricultural damage in surrounding crops in certain cases. The review also highlights those negative ecological relationships of alfalfa crops with biodiversity can be minimized, and positive effects may also be maximized under the appropriate management of this crop. Examples of such management actions include cut delays or higher cuts to avoid nest destruction, the use of grazing cattle to reduce the impacts of rodent pests, or reduced frequency of cutting or maintaining unharvested strips in the field to maximize positive effects on predatory arthropods and vole availability to raptors. We conclude that alfalfa crops can be considered globally beneficial for farmland biodiversity and a useful management tool for conservation in agricultural landscapes, for example as an AES, and that management should be adapted to particular taxonomical or functional groups.
... To meet the IUCN and MER criteria (Table 1), we modeled species extant distributions using the official Mexican land use and land cover vegetation maps produced by the Mexican National Institute of Statistics, Geography, and Informatics (INEGI; Capa Digital de Uso de Suelo y Vegetacion) for two time series: 2002 and 2014 (INEGI, Capa Digital de Uso de Suelo y Vegetación, Series III, 2005; Series VI, 2017). Even though some species can use transformed habitats (Ursua et al., 2005) it is unclear the extent in which each species is affected, and if they establish permanent resident and reproductive populations (Betts et al., 2019;Fahrig et al., 2019). In terms of biodiversity conservation, it is more favorable to adopt a more precautionary perspective, and assume that species are affected by anthropogenic activities (Sánchez-Cordero et al., 2005Fuller et al., 2007;Botello et al., 2015;Mayani-Parás et al., 2021). ...
An increasing number of species at risk raise concerns worldwide. While global assessments provide a comprehensive framework, national species conservation status is needed to provide specific policies. The IUCN Red List and the Mexican Norm (MER) methods were used to assign risk categories for 310 endemic species of terrestrial vertebrates at national and ecoregion levels. We used ecological niche models projected as species potential distributions, and refined species extant distributions including only remnant suitable habitat, to assess species risk assignments for Criterion A and B (IUCN Red List), and Criterion A, B, C, and D (MER). Of the total number of species, the IUCN Red List and MER report 71 and 155 species at risk, respectively. Our assessment assigned a risk category to 38 and 299 species, respectively. The discrepancies in the number of species between our proposal and the IUCN Red List and MER are striking and probably due to shortcomings of deficient information or expert opinion of species, standardization between methods, and the number and particular characteristics of criteria. Species occurring in the Mexican Transvolcanic Belt, the Great Plains and the Yucatan Peninsula ecoregions were at higher extinction risk than species occurring in the Mexican deserts, the Mexican High Plateau, the Southern Sierra Madre and the Western Sierra Madre ecoregions. Our proposal of using species potential and extant distributions models facilitates frequent species assessments, as conditions of risks fluctuate over time, and contributes to designing national and regional conservation programs of species and populations at risk.
... Previous work on habitat selection in this species (e.g., Morganti et al., 2021;Rodríguez et al., 2014;Ursúa et al., 2005) was conducted at the population level, and thus did not focus on the drivers of Table 1 Gamma GLMMs assessing colony and home-range scale drivers of lesser kestrel individual foraging habitat selection for grassland and non-irrigated crop for 10 populations in Italy. Significance was assessed through Wald's χ 2 tests (Fox and Weisberg, 2011). ...
Gradients of agricultural intensification in agroecosystems may determine uneven resource availability for predators relying on these man-made habitats. In turn, these variations in resource availability may affect predators' habitat selection patterns, resulting in context-dependent habitat selection. We assessed the effects of gradients of landscape composition and configuration on habitat selection of a colonial farmland bird of prey, the lesser kestrel (Falco naumanni), relying on 76 GPS-tracked nestling-rearing individuals from 10 populations scattered along an agricultural intensification gradient. Analyses were conducted considering two ecological levels of aggregation (the population and the individual) and two spatial scales of habitat availability (the colony surroundings and the individual home-range). Overall, non-irrigated croplands and semi-natural grasslands were the most preferred habitats at both spatial scales. At the colony scale, lesser kestrels showed a preference for grassland compared to non-irrigated crops, whereas the opposite was the case within individual home-ranges. Conversely, croplands were positively selected with comparable intensity at both spatial scales. Strong selection for grassland at the colony scale highlights the importance of this semi-natural habitat for the species. The weaker preference for grassland at the home-range scale is likely due to the phenology and structure of the vegetation in the late breeding season. Spatial scale differences in selection patterns may thus derive from spatio-temporal changes in resource availability through the breeding season. The strength of selection for the two most used habitats varied markedly among individuals. At the spatial scale of the colony, individual selection strength for grasslands increased with decreasing compositional diversity of the surrounding landscape, suggesting that agroecosystem heterogeneity may at least partly buffer the loss of semi-natural habitats. At the within home-range scale, higher cropland availability reduced the strength of individual preference for this habitat, suggesting a negative functional response possibly related to density-dependent processes acting on foraging movements. Our study provides evidence that farmland species show context-dependent habitat selection patterns in response to landscape gradients shaped by agricultural intensification as well as by intrinsic characteristics and habitat availability. Our findings highlight the importance of addressing both individual and population-level variability and considering multiple spatial scales in studies of habitat selection to inform species' management and conservation.
... Increased availability of crop patches that are repeatedly harvested during spring-summer, such as leguminous fodder (i.e. alfalfa Medicago sativa), that have largely replaced irrigated crops normally avoided by lesser kestrels (Ursúa et al. 2005), may have indeed favoured the expansion of the species in recently colonized areas (i.e. northern Italy, Morganti and Grattini 2018). ...
Farmland habitats host important populations of several threatened bird species. So far, how to reconcile farmland management with the maintenance of viable populations of these taxa is a major challenge for conservation biology. Southeastern Italy hosts ca 7000 pairs of breeding lesser kestrels Falco naumanni, representing one of the European strongholds of this small colonial raptor of conservation concern. We firstly assessed the relative importance of managed crops versus semi-natural grasslands in determining the local abundance of lesser kestrels at the landscape scale, and we successively studied the foraging habitat preferences at a smaller spatial scale. Surveys of foraging birds were associated with land-use collection at 191 homogeneous habitat sampling parcels from 14 plots of 16 km2 each, uniformly distributed over a 2400 km2 area. Each plot was visited six times during the 2017 breeding season (May–July). Land-use markedly changed along the season, unripe cereals being dominant in May, while harvested cereal crops prevailed in July. Land-use did not affect lesser kestrel distribution early in the season while foraging birds were more abundant in plots with a greater proportion of harvested cereal crops and a lower one of semi-natural grassland in the late breeding season. In accordance, the analysis of foraging habitat preferences within plots showed that in May unripe cereal crops and semi-natural grasslands were used proportionally to their availability. In June and July, harvested cereal crops were used more than expected from their availability, while semi-natural grasslands were significantly avoided. Our landscape-scale analysis thus indicates that semi-natural grasslands are much less used in comparison to harvested crops during the mid and late parts of the breeding season, suggesting that lesser kestrel may be able to take advantage of crop management practices more than other farmland birds of conservation priority.
... However, nowadays the agricultural production in Armenia is still based on extensive management systems, even though in the next future plantations will be irrigated and mechanical pruning and harvest will occur, especially in vineyards (Avetisyan 2010). Anyway, some evidence shows that the irrigation of crops could be favourable for raptor conservation in low-intensity farming systems (Eisenman 1971;Ursúa et al. 2005), even if the intensive irrigation, as well as heavy intensification of agricultural practices in general, is detrimental also for these birds (Bird et al. 1996;Tella and Forero 2000;De Frutos et al. 2015). ...
The species–habitat relationships can change during the year because of the seasonality of resources. Therefore, the investigation of habitat use by animals in each season plays a fundamental role in their conservation. The main aim of this research was to investigate the raptor community that spends the winter in Armenia, southern Caucasus, and to explore its relationship with environmental features, such as land use and topography. During January 2012, we collected data by carrying out 15 roadside counts along which we calculated three community parameters: the relative abundance, the species richness, and the species diversity. Then, we carried out a multiple linear regression with the Information-Theoretic Approach, to explain the relationship between the parameters and environmental variables. Besides, we computed a Canonical Correspondence Analysis (CCA) between the species and the environment around their observations. As a general pattern, the community was associated with permanent crops, maybe because of their heterogeneity, which in turn allows them to support higher densities of prey during the winter. The most abundant species was the Black Kite ( Milvus migrans ), followed by the Common Kestrel ( Falco tinnunculus ) and the Griffon Vulture ( Gyps fulvus ). To our knowledge, this is one of the first studies investigating the wintering raptor community in the Caucasus, with raptors generally studied in this area during the breeding season and migration.
... We also found that AL (cereals to a great extent, but also legumes, fodder crops, root crops and fallow land) were used in proportion to their availability by Lesser Kestrels, and avoided by males. Avoidance of cereals was also found by Ursúa et al. (2005) in the Ebro valley (North-East Spain). Therefore, our results confirm this behaviour as a general pattern in the species. ...
The reduction in both the extent and quality of foraging habitats is considered the primary cause of the Lesser Kestrel Falco naumanni population decline. A proper knowledge of Lesser Kestrel's foraging habitat selection at local scale is necessary for its conservation. Using accurate GPS devices, we investigated the patterns of local movements and land-cover type selection of 9 Lesser Kestrels in the main colony in Italy (Alta Murgia National Park, Gravina in Puglia and the surrounding rural areas) during the hatching period. The goals of our work were to individuate: 1) the preferred foraging habitats, 2) the potential sexual divergences in foraging movements and in 3) foraging habitat selection, 4) the relationship between foraging movements and the spatial arrangement of land codes. We detected significant sexual divergences in foraging movements and habitat selection. Lesser Kestrels preferred pseudo-steppes and significantly avoided ligneous crops and forested areas. While males selected positively pseudo-steppes, females used both pseudo-steppes and cereals in proportion to their availability. Foraging selection was influenced by the interplay between the spatial arrangement of land codes and the sexual divergences in foraging strategies. On the basis of our results, we have been able to propose suitable local-scale conservation actions to the Alta Murgia National Park and to the local administrations: a) the enlargements of the park's boundaries; b) the purchasing of land parcels; c) the provision of suitable nesting sites near the higher quality areas; d) the optimal timing for harvesting. Our study is the first contribution to the assessment of the foraging strategies and the necessary conservation policies of the Lesser Kestrel in Southern Italy.
... The Lesser Kestrels of these colonies preferably use non-irrigated arable land and pastures, where they find a large number of insects, but many of these are being replaced by vineyards. These changes in land use alter the habitat and the types of prey that can be found (Ursúa et al. 2005;García et al. 2006;Catry et al. 2012Catry et al. , 2014 and in addition, the vineyards imply an added danger due to the increasingly used cultivation technique in espalier, with wires to hold the vines against which the Lesser Kestrels and other birds can collide. Therefore, managing these lands around the colonies is of great importance for the conservation of this species (Donázar et al. 1993;Bustamante 1997;De Frutos et al. 2010). ...
Abstract Background The loss of traditional agropastoral systems, with the consequent reduction of foraging habitats and prey availability, is one of the main causes for the fast decline of Lesser Kestrel (Falco naumanni). To promote the conservation of the Lesser Kestrel and their habitats, here we studied the foraging activities patterns of this species during the breeding season. Methods Between 2016 and 2017, we captured and tagged 24 individuals with GPS dataloggers of two colonies in Villena (eastern Spain) with the goals of estimating the home range sizes of males and females, evaluating the differences in spatial ecology between two colonies located in different environments: natural and beside a thermosolar power plant, and investigating habitat selection. Results Considering the distances before July 15, date until which it can be assured that the chicks remain in the nest in our colonies, there were significant differences with the distances to the nest in relation to the colony of the individuals: Lesser Kestrels from the thermosolar power plant colony had a greater average distance. The average size of home range areas was 13.37 km2 according to 95% kernel, and there were also significant differences in relation to colony: the individuals from the thermosolar power plant colony used a larger area (22.03 ± 4.07 km2) than those from the other colony (9.66 ± 7.68 km2). Birds showed preference for non-irrigated arable lands and pastures. Conclusions Despite the differences between the two colonies, the home ranges of both are smaller or similar to those observed in other European colonies. This suggests that Lesser Kestrels continue to have adequate habitats and a good availability of prey. Therefore, the extension and proximity of the plant does not imply a great alteration, which highlights the importance of maintaining the rest of the territory in good conditions to minimize the impact.
... To explain this pattern, we can hypothesize that vegetation structure is a main determinant of foraging suitability for insectivores (see e.g., Atkinson, Buckingham, & Morris, 2004;Devereux, McKeever, Benton, & Whittingham, 2004), and that dense and tall vegetation decreases the foraging efficiency of Lesser Kestrels (Catry, Franco, & Moreira, 2014). This hypothesis is supported by the observation that excessive irrigation correlates with the decrease of foraging activity of the Lesser Kestrel (Ursúa, Serrano, & Tella, 2005), which seems not able to feed over very tall vegetation (above~80-100 cm height; Morganti et al., 2018). The results of our model thus suggest that wet conditions in winter and early spring (boosting insect abundance), associated with rather dry conditions in May (avoiding excessive vegetation growth) are probably ideal for the highland population of the Lesser Kestrel. ...
The sensitivity of population trends to the climate and environment is generally
considered a species-specific trait. However, evidence that populations may show
different responses to the climate and environmental conditions is growing.
Whether this differential sensitivity may arise even among neighboring populations
remains elusive. We compared the trends of two neighboring populations of the
Lesser Kestrel Falco naumanni, using data from a 12-year survey of 158 colonies
in Sicily, Italy; the two populations inhabiting a lowland and an highland area,
respectively. Population trends were modeled through the TRIM algorithms implemented
in R (package rtrim). A reversed U-shaped population trend was observed
in the lowland, while the highland population showed oscillations around a stable
trend. Sahel rainfall 2 years before each annual survey significantly affected population
variation in the lowland, while rainfall in March and an index of primary
productivity in the breeding areas affected population variation in the highland.
This suggests that the population in the lowland may be limited mainly by winter
survival in Sahel, because the lowland may be an optimal breeding area for this
species. In contrast, the highland population, which occupies a different part of the
climatic niche of the species, may be limited mainly by reproductive output,
because rainfall in March and the primary productivity in May could represent prey
availability immediately before and during the breeding months. Overall, our findings
suggest that population-specific environmental sensitivity might occur even
over small (<100 km) geographical scales, highlighting the need for population-
Q3 specific conservation strategies.
... Worldwide agriculture is one of the main factors influencing the general decline in biodiversity as well as bird species. Effective conservation strategies depend on the type of relationship between biodiversity and land-use intensity, and on knowledge of foraging chains in this system (Ursua et al. 2005, Kleijn et al. 2009). Raptors are top predators in agroecosystems, but their foraging and food niches have been evaluated only partially there. ...
The red-footed falcon and Eurasian falcon represent two syntopical falcon species. While the Eurasian falcon is considered a common and numerous species in Slovakia, the red-footed falcon population has undergone a considerable decline during the past few decades. Nowadays it nests in a single locality in Slovakia, the Sysľovské polia Special Protection Area, which forms the northern and fragmented border of the species distribution area in Europe. By analysing prey remains from 9 nests (from 1998, 2001, 2013, 2014 and 2016), we identified 433 prey items belonging to 35 taxa and 9 orders. Every year, invertebrates made up the major part of the diet spectrum, in which
... This active search pattern gains further evidence if we consider that non-significant results were obtained for clover cover, both at male and female sites. The importance of legume crops for steppe-birds has been described in several studies Lane et al. 1999;Ursúa et al. 2005). For the little bustard in particular, the availability of alfalfa (Medicago sativa) fields in cultivated areas was pointed as one of major factors influencing the breeding ecology of the species (Bretagnolle et al. 2011;Jiguet et al. 2002;Salamolard and Moreau 1999). ...
The effect of management of Mediterranean dry grasslands on farmland bird populations has been scarcely studied. We investigated population productivity and habitat selection of the little bustard Tetrax tetrax in the late breeding period, in grassland dominated landscapes of Southwest Iberia. Specifically our goals were to investigate how these parameters are influenced by the management of (1) grazing and (2) hay production. We conducted bird counts from June 22nd to July 4th (2012 to 2016) using low speed 4x4 car surveys. The relationship between the density of the species, population productivity and farm management (grazing and haying) was evaluated using Generalized Linear Mixed Models and Kruskal-Wallis tests. Male and female densities were significantly higher in short vegetation comparatively to all other types of vegetation considered, but population productivity was similar in short and medium vegetation. Hay stubbles were found to be unattractive for the species. The availability of suitable habitats depends on the timing of grazing, notably of seasonal (spring) grazing. Species density was higher in fields ungrazed during winter and with moderate to high stocking rates in spring (around 0.8 LU/ha or higher), depending, at least for males and females, on each year’s weather characteristics. We conclude that low to moderate stocking rates during winter and spring are essential to ensure successful breeding and thus population persistence. Current levels of haying in our study area are detrimental for the species’ conservation.
... Habitat availability in rural areas was estimated by recording the number of each habitat patch on both sides of the unpaved roads. Thus, we measured habitat availability in real time and at the same spatial scale in which habitat use is estimated, assuming that, in large sample sizes, plot size approaches the mean size of all plots evaluated 72,73 . An average plot length (i.e., the length of the plot in contact with the road) was estimated by measuring it in 60 randomly selected fenced plots across the study area using aerial photographs. ...
Although habitat transformation is one of the main causes of biodiversity loss, there are many examples of species successfully occupying and even proliferating in highly human-modified habitats such are the cities. Thus, there is an increasing interest in understanding the drivers favoring urban life for some species. Here, we show how the low richness and abundance of predators in urban areas may explain changes in the habitat selection pattern of a grassland specialist species, the burrowing owl Athene cunicularia, toward urban habitats. Predation release improves the demographic parameters of urban individuals, thus favoring an increment in the breeding density of the species in urban areas that accounts for the apparent positive selection of this habitat in detriment of the more natural ones that are avoided. These results suggest that traditional habitat selection analyses do not necessarily describe habitat choice decisions actively taken by individuals but differences in their demographic prospects. Moreover, they also highlight that cites, as predator-free refuges, can become key conservation hotspots for some species dependent on threatened habitats such as the temperate grasslands of South America.
... The demand for oilseed rape is increasing along with that for biofuel production. For example, the sown area of oilseed rape increased from 600 ha in 1990 to 98,000 ha in 2010 in Estonia; more recently, the sown area of maize [which is also an unsuitable foraging habitat for raptors (Ursúa et al. 2005;Cardador and Mañosa 2011)] has increased in a similarly drastic manner [from 2000to 8,500 ha in 2011(Statistics Estonia 2016]. Fortunately, some recent positive trends for the Eagles were also noted. ...
Anthropogenic loss of biodiversity is often indicated by the disappearance of top predators. However, some of them have adapted to man-made agricultural landscapes. Among raptors, one such example is the Lesser Spotted Eagle. We compiled an exhaustive data set on foraging habitat composition of this species by direct field mapping and detailed land cover maps to study the effect of various agricultural management practices on its occupancy of home ranges and productivity, as well as on its habitat utilization and hunting success. Home ranges of the Lesser Spotted Eagle contained more natural grasslands (7.6%) and other agricultural biotopes (29.9%) than expected by random, and they preferred to breed close to managed agricultural biotopes. They hunted preferably on grasslands, where they spent 86% of their time, especially on managed grasslands, but avoided arable fields. In total, 51% of the Lesser Spotted Eagle attacks were successful, and we detected no differences in hunting success among habitats. Nests of successfully breeding birds were surrounded by more crops/cultivated grassland on a rotational basis (19.0%), as well as by managed natural grassland (1.1%), than those of unsuccessful pairs (16 and 0.7%, respectively). We also detected a negative impact of oilseed rape fields and mowed cultivated grassland on the reproductive success of the Lesser Spotted Eagle, but these effects were not consistent over the years. Our results suggest that, although the Lesser Spotted Eagle is well adapted to foraging in traditional farmland, it is threatened by changes in agricultural practices and an increasing sown area of some crops, such as oilseed rape. Cultivation of various crops and retaining of grasslands, interspersed with set-aside and non-agricultural habitat patches, promoted by the European Union greening policy, would be favourable to the Lesser Spotted Eagle.
... All rights reserved.' Tella et al. 1998, Franco and Sutherland 2004, Sarà 2010, land intensification could produce suitable habitats, such as alfalfa or artichoke fields (Ursua et al. 2005, Di Maggio et al. 2016). In addition, we did not include dispersal in our modelling evaluation (Rodríguez-Rey et al. 2013), because data from the recent area of expansion (Araújo et al. 2005) is limited, as well as because the lesser kestrel has complex dispersal dynamics in a close range to core-colonies (e.g. ...
Climate warming would theoretically create conditions for the breeding range expansion of pseudo-steppe Mediterranean and long-distance migrant species and provide the possibility for these to overwinter in the same breeding areas. However, contemporary changes in rainfall regimes might have negative effects on the climate suitability and in turn, shrink species potential range. The lesser kestrel, Falco naumanni, is highly sensitive to rainfall oscillations and has recently extended its Italian breeding range towards northern latitudes and increasing its wintering records. We modelled the effects of temperature and rainfall on current and future climate suitability for lesser kestrels in both the breeding and wintering periods by using MaxEnt. Models were based on the distribution of 298 colonies and 45 wintering records. Future climate suitability was assessed under eight different scenarios.
... Thus, the potential negative effects that a high reliance on alfalfa as a winter food resource may have on the Spanish Little Bustard population and those of other farmland birds deserve further attention from an ecological, nutritional, and toxicological point of view. In the meantime, although the effectiveness of providing legume crops as a measure to increase habitat quality and carrying capacity for bustards in agricultural landscape has been well established (Wolff et al. 2001, Ursúa et al. 2005, Bretagnolle et al. 2011, Kovács-Hostyánszki and Báldi 2012, Ponce et al. 2014, we suggest that these crops should be included within a web of a diverse habitat matrix providing different suitable and complementary habitats such as fallow land (Silva et al. 2004) to supply alternative and varied food resources. ...
Foraging strategies and diet selection play an essential role in individual survival and reproductive success. The study of feeding ecology becomes crucial when it concerns endangered species such as the Little Bustard (Tetrax tetrax), whose populations are suffering strong declines as a consequence of agricultural intensification. Despite the fact that several populations are overwintering in areas affected by agricultural transformation, nothing is known about how feeding behavior responds to these changes. We studied for the first time the winter diet composition of the Little Bustard in Spain and compared it between areas with two different farming systems: dry and irrigated farmland. Diet was studied through the micro-histological analysis of 357 droppings collected in 16 locations across the wintering range of the Little Bustard in Spain. Up to 62 plant species were identified. Most consumed species were cultivated legumes (46.7%) and dicotyledon weeds (45.6%), while monocotyledons were scarcely consumed (7.7%). Diet composition differed significantly between dry and irrigated farmland areas. In irrigated areas, diet was mainly composed of legumes, in particular alfalfa (Medicago sativa). In contrast, in dry farmland areas diet was more diverse, composed mainly of weeds (Compositae, Papaveraceae, and Cruciferae) and also cultivated legumes, particularly vetch (Vicia sativa). These results suggest that legume crops could be an effective measure to improve habitat quality in areas with scarce food resources. However, in the case of irrigated areas, the strong reliance on alfalfa could make the Little Bustard more vulnerable to changes in land use. This study is the first step to understand the winter trophic requirements of the endangered Little Bustard, but further research is necessary to understand the food requirements of this species during the entire annual cycle.
... Further, in avoiding competition or disturbance birds may be forced to use habitats they do not actually prefer, decoupling distribution from habitat preferences. In some circumstances, the behaviour and use of habitat resources may be directly observed by recording habitats where individuals forage or roost (Bakaloudis et al., 1998;Ursúa et al., 2005), although biases associated with, for example, habitat-mediated detectability are sometimes unavoidable. These problems can be circumvented with telemetry-based data which are being incorporated routinely in to the study of raptor-habitat relationships since the pioneer work of Southern (1964). ...
... This reflects patterns seen in other systems, whereby some agricultural transformation may benefit avifauna [63,[69][70][71] but beyond a certain threshold level of habitat loss the balance is tipped and can lead to rapid species declines or loss [72]. For example, in lesser kestrels Falco naumanni low level agricultural transformation has been associated with an increase in breeding productivity [73]. However, beyond a threshold of habitat conversion for agriculture, suitable foraging habitat and an adequate prey base are not maintained potentially resulting in reduced reproductive output, such as that seen in Eurasian kestrels Falco tinnunculus [74]. ...
Information on movement ecology is key in understanding the drivers and limitations of life history traits and has a potential role in indicating environmental change. Currently we have a limited understanding of the parameters of movement of territory-bound raptors, which are sensitive to environmental change. In this study we used GPS tracking technology to obtain spatially (within 3 m) and temporally (c. 3 mins) high-resolution movement data on a small sample of Verreaux’s eagle Aquila verreauxii during the pre-laying period (n = 4) with one additional example during the chick rearing period. We present GPS-derived home range estimates for this species and we examine temporal (timing, duration, frequency and speed) and spatial (total path length and maximum distance from nest) patterns of trips away from the nest. For eagles tagged in the agriculturally developed Sandveld region (n = 3), which is made up of a mosaic of land use types, we also undertook a habitat selection analysis. Home ranges were small and largely mutually exclusive. Trip activity was centred around midday, which is likely to be related to lift availability. Our habitat selection analysis found that eagles selected for near-natural and degraded habitat over natural or completely modified areas, suggesting that these eagles may have benefitted from some of the agricultural development in this region. Although our sample sizes are small, the resolution of our tracking data was essential in deriving this data over a relatively short time period and paves the way for future research.
... Further, in avoiding competition or disturbance birds may be forced to use habitats they do not actually prefer, decoupling distribution from habitat preferences. In some circumstances, the behaviour and use of habitat resources may be directly observed by recording habitats where individuals forage or roost (Bakaloudis et al., 1998;Ursúa et al., 2005), although biases associated with, for example, habitat-mediated detectability are sometimes unavoidable. These problems can be circumvented with telemetry-based data which are being incorporated routinely in to the study of raptor-habitat relationships since the pioneer work of Southern (1964). ...
Birds of prey have been, in comparison to other avian groups, an uncommon study model, mainly due to the limitations imposed by their conservative life strategy (low population density and turnover). Nonetheless, they have attracted a strong interest from the point of view of conservation biology because many populations have been close to extinction and because of their recognised role in ecosystems as top predators and scavengers and as flagship species. Today, after more than a century of persecution, and with the exception of some vultures still very much affected by illegal poisoning, many populations of birds of prey have experienced significant recoveries in many regions of Spain and the European Mediterranean. These changes pose new challenges when addressing the conservation of raptors in the coming decades. On this basis, and from a preferentially Mediterranean perspective, we have focused our attention on the need of describing and quantifying the role of these birds as providers of both regulating (rodent pest control and removal of livestock carcasses) and cultural ecosystem services. Moreover, we revisited persisting conflicts with human interests (predation of game species) and call attention to the emergence of new conflicts with a strong social and media component such as the predation on live cattle by vultures. Also, the rampant humanization of the environment determines the need for new solutions to the growing, yet scarcely explored, problem of accidents in new infrastructures such as mortality in wind farms. Finally, we explored in depth the ecological response of birds of prey to large-scale habitat changes such as urbanisation and abandonment of marginal lands that are also expected to increase in the near future. We urgently need more scientific knowledge to provide adequate responses to the challenge of keeping healthy populations of avian predators and scavengers in a rapidly changing world.
... In niederschlagsarmen Gebieten wie den Zentralalpen kann auch die Bewässerung der Wiesen zu einer Intensivierung führen (Graf et al. 2014). Untersuchungen zu den Auswirkungen der Bewässerung auf Brutvögel sind selten und betreffen meist Steppengebiete (Brotons et al. 2004, Ursúa et al. 2005, De Frutos et al. 2015 jedoch praktisch nie die inneralpinen Trockengebiete. Im Rahmen verschiedener Projekte untersuchten wir die Auswirkungen der Wiesenbewässerung auf die Brutvögel. ...
In many parts, populations of meadow-breeding birds have strongly decreased, also in the Central Alps. Intensification of agricultural practices has often been mentioned as primary cause for the decline. In areas with rather low precipitation in the Central Alps, irrigation can lead to intensification. Thus far, only a few studies have analysed the effect of irrigation on meadowbreeding birds. In this article, two studies are presented which focus on different aspects of this subject:
Studies from the Engadin show that recent irrigation has in fact led to an intensified use of meadows, but that its impact on the vegetation has only fully become visible ten to twenty years after implementation of irrigation. Together with the installation of modern sprinklers, drastic changes in the avifauna were recorded between 1987/88 and 2009/10. Meadow-breeding birds displayed strong declines which were presumably in part caused by modern irrigation.
Results from the Vinschgau (Tyrol) indicated that the type of irrigation – traditional irrigation with water channels versus modern irrigation with sprinklers – had no direct influence on breeding birds. However, there
is a potential risk that a switch to modern irrigation techniques might lead to a general intensification of grassland use.
... The introduction of crops that are structurally different from the original vegetationsuch as olive groves or even herbaceous crops whose density or height is differentleads to habitat diversification and fragmentation. When the new habitats are similar to original ones, there can be limited negative effects or even positive ones (Wolff, 2005); when instead the differences are significant, and anthropization increases (infrastructure building), effects can be strongly negative (Brotons et al., 2004;Ursúa et al., 2005). Of the animal groups that are most sensitive to these changes, birds are undoubtedly the best studied (Bota et al., 2005). ...
Steppe habitats are considered to be of great interest in terms of biodiversity conservation, specially for birds, with many rare and endangered species breeding in these habitats. The conversion to crops or other forms of cultivation, is universally recognised as the major threat for the conservation of these habitats and their biodiversity. During the 20th century, particularly in the Mediterranean basin, large areas of natural steppe habitats were plowed, causing a large decline in many bird species. Nowadays, although the economical and social context has deeply changed, many areas of steppe habitats are facing the same threat. In this paper we analysed the effects of different landscape mosaics of crops and steppes on breeding birds in the Alta Murgia National Park, one of the most important steppe areas in Italy. Specifically, we tested the effect of some landscape metrics, descriptive of crops-steppes spatial arrangement, on five Alaudidae species: Calandra lark, Skylark, Greater short-toed lark, Woodlark and Crested lark. Analysis were carried out using MaxEnt.The analyses did not find substantial differences between steppe and cropland, which would seem to be equally suitable habitats for these species. With the only exception of Greater short-toed lark, which shows a degree of ecological plasticity, all other species show a strong preference for landscapes with a high degree of connectivity and low fragmentation. Our results seem to suggest that the co-presence of crops and steppes, if the fragmentation degree at landscape scale is low, does not negatively affect the presence and abundance of steppe species, and represents a highly suitable habitat that can support nationally-important populations of endangered species such as the Calandra lark.
... The phenomenon described her is not unique, Lesser Kestrels in Spain mainly hunt at the edges of arable fields and set aside fields, and the extensively cultivated cereal fields (Bustamante 1997, Franco & Sutherland 2004, De Frutos et al. 2009). Lesser Kestrels also catch prey faster in ploughed fields than in natural grasslands or in the edges of vegetation (Rodriguez et al. 2006), and the hunting success is closely related to the used agrotechnics (Ursua et al. 2005, Catry et al. 2011. ...
We studied hunting success of 13 male Red-footed Falcons by radio-telemetry in the second phase of chick rearing. We coded 484 hunting events, and the success measured in captured prey biomass/minute was exceedingly high in corn fields. This is mainly caused by the fact that the effectiveness of hunting for vertebrate prey was high on the harvested stubble fields. Moreover the observed falcons hunted for insects in these stubble field and alfalfa fields most successfully. In the studied habitat the chick feeding period of Red-footed Falcons coincide with the harvest of cereal fields, and the suddenly created lower vegetation cover increases temporarily the accessibility of prey items.
Till they were available and could be efficiently harvested, the falcons hunted on the fields within a 1 km radius from the nesting colony for the more profitable vertebrate prey. Thereafter they searched for vertebrate prey on the fields located at average 1–2.5 km distance from the colony. In the later zone falcons started to hunt insects, too, but approximately third of the captured insects (36.4%) was consumed immediately and was not delivered to the colony. Conversely larger prey was almost always (98.1%) carried directly to the nest site. Only one part of the Field Voles was observed to be eaten regularly: the brain. Finally later in the breeding season falcons were observed more and more often to hunt in the nearest fields again, this time for insects. Probably due to the depletion of the distant plots, the closer fields with lower investment became a competitive alternative for the birds.
Our results highlight the fact that even for such characteristic short-grass specialist birds as Red-footed Falcons the prey sources offered by arable lands might be temporarily exploited with success. Hence it is very important to integrate the measures offered by agri-environment schemes into the management of this threatened species.
... During the course of our investigations on the lesser kestrel, that began in 1988 (Negro 1997), we have always pursued to get an accurate knowledge of their daily movements at their breeding grounds. Applying radio transmitters and direct behavioral observations of unmarked individuals we have been able to determine foraging habitat preferences (Donázar et al. 1993;Ursua et al. 2005;Ribeiro 2007) but soon realized that we lost track of the birds more often than we located them, biasing our studies to locations near the breeding colony. Later on, geolocators have permitted us to determine that kestrels from southern Spain wintered in the Sahel area of western Africa . ...
Unmanned Aerial Systems (UAS) have been used for decades in the military
field, mainly in dangerous or tedious missions where it is preferable to send a vehicle equipped with sensors
than to use human piloted conventional aircrafts for
information gathering. In recent years technology has advanced, the market has grown exponentially,
prices have descended and the use of the systems is simpler, which has led to the incorporation of the UAS to the civilian world. UAS have proven useful in ecology related tasks, such as animals monitoring and habitats characterization, and their potential for spatial ecology has been pointed out, but to date there are just a few studies addressing their specific use in conservation biology.
This Ph.D. thesis attempts to fill the gap of knowledge in practical functions
of small UAS in conservation biology. It describes for the first time the use of these systems in an immediately applicable way for impact assessment of infrastructures and protection of endangered species. It also presents UAS as a tool for obtaining high- resolution spatiotemporal
information, which helps to understand habitat use in
rapidly changing landscapes. Furthermore, it demonstrates that these systems can provide information as valid as the obtained by conventional techniques on the spatial distribution of species in protected areas.
The experiments performed in the frame of this thesis show that low cost
small UAS equipped with embarked cameras that provide high-resolution images offer the possibility of monitoring the environment at
the researcher’s desired
frequency and revisiting sites to perform systematic studies, which is valuable for ecological research.
The results also revealed that UAS use in conservation biology has some
constraints, mainly related with the scope of the missions, the limiting costs of the systems, operating restrictions associated to weather, legal limitations and the need of specialized personnel for operating the systems, as well as some difficulties for data analysis related with image processing.
Overall, given the novelty of the subject and the importance it is expected to have in the near future, I consider that providing information on the capabilities and limitations of UAS, based on practical experiments in conservation biology, is not only of scientific interest but combines environmental and industry interests, which brings added value and usefulness of this thesis to society.
... We also found that AL (cereals to a great extent, but also legumes, fodder crops, root crops and fallow land) were used in proportion to their availability by Lesser Kestrels, and avoided by males. Avoidance of cereals was also found by Ursúa et al. (2005) in the Ebro valley (North-East Spain). Therefore, our results confirm this behaviour as a general pattern in the species. ...
The reduction in both the extent and quality of foraging habitats is considered the primary cause of the Lesser Kestrel Falco naumanni population decline. A proper knowledge of Lesser Kestrel's foraging habitat selection at local scale is necessary for its conservation. Using accurate GPS devices, we investigated the patterns of local movements and land-cover type selection of 9 Lesser Kestrels in the main colony in Italy (Alta Murgia National Park, Gravina in Puglia and the surrounding rural areas) during the hatching period. The goals of our work were to individuate: 1) the preferred foraging habitats, 2) the potential sexual divergences in foraging movements and in 3) foraging habitat selection, 4) the relationship between foraging movements and the spatial arrangement of land codes. We detected significant sexual divergences in foraging movements and habitat selection. Lesser Kestrels preferred pseudo-steppes and significantly avoided ligneous crops and forested areas. While males selected positively pseudo-steppes, females used both pseudo-steppes and cereals in proportion to their availability. Foraging selection was influenced by the interplay between the spatial arrangement of land codes and the sexual divergences in foraging strategies. On the basis of our results, we have been able to propose suitable local-scale conservation actions to the Alta Murgia National Park and to the local administrations: a) the enlargements of the park's boundaries; b) the purchasing of land parcels; c) the provision of suitable nesting sites near the higher quality areas; d) the optimal timing for harvesting. Our study is the first contribution to the assessment of the foraging strategies and the necessary conservation policies of the Lesser Kestrel in Southern Italy.
... Steppe birds are open-habitat specialists associated with low-intensity farming because they prefer short vegetation and avoid dense cover (Tella et al., 1998;Concepción and Díaz, 2011;Fischer et al., 2011). For example, the significant negative selection of irrigated crops by the Lesser Kestrel is well documented (Tella and Forero, 2000;De Frutos et al., 2007De Frutos and Olea, 2008 but see Ursúa et al., 2005). Vegetation cover may increase under agricultural intensification through irrigation in Mediterranean farmlands, especially dominated by maize monocultures (e.g., higher frequency of taller crops as maize, and higher number of trees and large shrubs; González-Estébanez et al., 2011; see more negative effects of maize on birds in Best et al., 1997;Meehan et al., 2010). ...
... However, not every species responds equally to land transformation. Landscape management may lead to the appearance of new environments [1] that may enhance landscape heterogeneity and thus provide suitable habitats for species tolerant to anthropogenic alterations [7][8][9][10][11]. In this context, species' tolerance to anthropogenic changes emerges as a key feature influencing their persistence in agricultural systems [12][13][14]. ...
Landscape conversion by humans may have detrimental effects on animal populations inhabiting managed ecosystems, but human-altered areas may also provide suitable environments for tolerant species. We investigated the spatial ecology of a highly mobile nocturnal avian species–the red-necked nightjar (Caprimulgus ruficollis)–in two contrastingly managed areas in Southwestern Spain to provide management recommendations for species having multiple habitat requirements. Based on habitat use by radiotagged nightjars, we created maps of functional heterogeneity in both areas so that the movements of breeding individuals could be modeled using least-cost path analyses. In both the natural and the managed area, nightjars used remnants of native shrublands as nesting sites, while pinewood patches (either newly planted or natural mature) and roads were selected as roosting and foraging habitats, respectively. Although the fraction of functional habitat was held relatively constant (60.9% vs. 74.1% in the natural and the managed area, respectively), landscape configuration changed noticeably. As a result, least-cost routes (summed linear distances) from nest locations to the nearest roost and foraging sites were three times larger in the natural than in the managed area (mean ± SE: 1356±76 m vs. 439±32 m). It seems likely that the increased proximity of functional habitats in the managed area relative to the natural one is underlying the significantly higher abundances of nightjars observed therein, where breeders should travel shorter distances to link together essential resources, thus likely reducing their energy expenditure and mortality risks. Our results suggest that landscape configuration, but not habitat availability, is responsible for the observed differences between the natural and the managed area in the abundance and movements of breeding nightjars, although no effect on body condition was detected. Agricultural landscapes could be moderately managed to preserve small native remnants and to favor the juxtaposition of functional habitats to benefit those farm species relying on patchy resources.
... This means that, for this type of management, during most of autumn and whole of winter, there are no stubbles available. It is important to note that extensive cereal farming is also the agricultural system that best satisfies the ecological requirements of other priority grassland birds, such as the great bustard (Otis tarda) (Kollar, 1996;Rocha, 2006) and the lesser kestrel (Falco naumanni) (Biber, 1996;Ursúa et al., 2005). ...
The little bustard is a grassland bird with more than half of its population concentrated in the Iberian Peninsula. It has declined dramatically over the last decades, mainly due to changes in agricultural practices and is now one of Europe’s most threatened species. Being so reliant on human active management, it is essential to understand the main factors that influence its abundance, from where sound agricultural practices can be identified and reverted into agro-environmental prescriptions. The main objective of this thesis is to analyze these factors along the yearly cycle and at different scales, within a population that still occurs in high densities.
At a regional landscape scale it was demonstrated that the highest densities were found in less heterogeneous landscapes with greater availability of continuous grasslands, their preferred breeding habitat, rather than in heterogeneous landscapes with small agricultural fields, as stated in previous works. At the plot scale, female and male habitat preferences, were found to be similar, preferring to occur in larger grassland fields with short vegetation. Male density was found to vary only with grassland field size. Larger grassland fields presented higher levels of vegetation heterogeneity, which possibly favors the occurrence of both males and females, at a micro-habitat scale. During the post-breeding season important population shifts were recorded, due to the abandonment of their breeding grounds towards areas with more productive soils, with greater availability of green plants i.e. food availability. Particularly during the summer season the little bustard was found to avoid grasslands, showing that their habitat preferences vary seasonally. The agricultural system that better fits the little bustard’s habitat needs along the yearly cycle is the extensive cereal farming. Finally, the presence of overhead transmission power lines was identified as a new threat for the species, by creating an avoidance effect, negatively affecting its distribution and abundance.
... We analyzed habitat selection in PPRB, PGF, and urban areas with the Savage selectivity index, as described by Ursúa et al. (2005): ...
We examined daily activity patterns, flock-size variations, use of vertical space, and small-scale habitat selection of the New Caledonian Parakeet (Cyanoramphus saisseti), Horned Parakeet (Eunymphicus cornutus), and New Caledonian Rainbow Lorikeet (Trichoglossus haematodus deplanchii) on mainland New Caledonia. All three species had bimodal patterns of activity, with most encounters occurring in the morning and a second smaller peak of encounters in the late afternoon. The parakeets were usually seen singly or in twos, and most flocks contained fewer than four individuals. Parakeet flocks remained relatively consistent in size through the day and through the year. Most Rainbow Lorikeet flocks contained only a few individuals, though some reached up to 40 birds. Rainbow Lorikeets were encountered mainly in small flocks during the breeding season from September to January, and their average flock size was higher and more variable for the rest of the year. Rainbow Lorikeets selected valley forest and urban areas, where they were most common in parks and gardens. New Caledonian Parakeets favored slope forest over valley forest, and they foraged low, either at the edge of forest, in slope forest, or in maquis (shrubland). Horned Parakeets generally fed at greater heights than did New Caledonian Parakeets, preferred valley forest to slope forest, and avoided maquis. We suggest that the observed difference in habitat use between the New Caledonian Parakeet and Horned Parakeet is the result of spatial resource partitioning, which allows these closely related species to coexist.
Examinamos los patrones de actividad diaria, las variaciones del tamaño de la bandada, el uso del espacio vertical y la selección de hábitat de pequeña escala de Cyanoramphus saisseti, Eunymphicus cornutus y Trichoglossus haematodus deplanchii en Nueva Caledonia. Las tres especies tuvieron patrones bimodales de actividad, con la mayoría de los encuentros ocurriendo en la mañana y un segundo pico más pequeño de encuentros a finales de la tarde. C. saisseti y E. cornutus fueron vistos usualmente solas o en dúo, y la mayoría de las bandadas contuvo menos de cuatro individuos. El tamaño de las bandadas de estas dos especies permaneció relativamente consistente durante el día y a lo largo del año. La mayoría de las bandadas de T. h. deplanchii contuvieron sólo unos pocos individuos, aunque algunas alcanzaron las 40 aves. T. h. deplanchii fue encontrada principalmente en pequeñas bandadas durante la estación reproductiva, de septiembre a enero, y su tamaño promedio de bandada fue más grande y más variable para el resto del año. T. h. deplanchii seleccionó valles con bosque y áreas urbanas, donde fueron más comunes en parques y jardines. C. saisseti prefirió las laderas boscosas por sobre los valles con bosque y forrajeó bajo, ya sea en el borde del bosque, en laderas boscosas o en maquis (arbustales). E. cornutus usualmente se alimentó a mayor altura que C. saisseti, prefirió los valles con bosque más que las laderas con bosque y evitó el maquis. Sugerimos que las diferencias observadas en el uso de hábitat entre C. saisseti y E. cornutus es son el resultado de la partición espacial de los recursos, lo que permite que coexistan estas especies estrechamente relacionadas.
... Therefore, the availability of fields with low vegetation height reaches a maximum at this time and, as suggested by models for successful strikes and the selectivity index, kestrels may profit from ploughing and sowing activities because they improve accessibility to fossorial species such as earthworms, field crickets and the mole cricket Gryllotalpa gryllotalpa , which has been found to be preferentially consumed during courtship and incubation periods (Choisy et al. 1999, Rodriguez et al. 2010, Catry et al. 2012a ). The reported avoidance of ploughed fields (Ursúa et al. 2005 ) or their use in accordance with their availability in other areas (Tella et al. 1998, García et al. 2006 ) may be due to the time elapsed since fields were ploughed, which probably influences prey availability. The preference for areas with short vegetation may also explain the reported preferences for stubble over unharvested cereals (Donázar et al. 1993 ), which was also found in our study (wheat during the nestling period is primarily in the form of stubble), and grazed fallow over ungrazed fallow ). ...
We studied foraging habitat selection by Lesser Kestrel Falco naumanni throughout the breeding period in south-west Spain by means of transects on which foraging observations were recorded. We focused on the effects of habitat and crop type, but also on the effect of vegetation structure and the presence of agricultural activities in the field on Lesser Kestrel use. We considered both the accumulated use of the foraging area during the breeding season and the instantaneous forag-ing habitat selection by kestrels. Foraging habitat selection was highly dynamic following crop development and agricultural activities. Almost all major arable crop types showed positive selec-tion during some part of the breeding cycle. Accumulated use by kestrels demonstrated positive associations with wheat and cotton fields and negative selection of permanent habitat types, such as forested areas, woody crops and built-up areas that have no prey or are not used by the species due to unfavourable structure. Vegetation structure appears to play a major role in instantaneous foraging selection. Lesser Kestrels select fields with short vegetation and intermediate cover. They also forage on field margins and where agricultural activities such as ploughing or har-vesting that facilitate access to prey are being conducted. Our results help to clarify apparent controversies among previous studies on the subject, highlighting the importance of the het-erogeneity of agricultural landscapes around colonies (crops at different growth stages which provide variable vegetation height and cover during the breeding cycle) and the effect that agricultural activities have on facilitating access to prey. Beyond the species-specific approach, our work encourages further studies on habitat selection by farmland birds to account not only for human-based categorisation of habitats (e.g. crop type) but also on objective measures such as vegetation height and cover that influence access to prey and better reflect the high dynamism of agricultural landscapes.
... The shift from rain-fed to irrigated crops in Mediterranean Europe has had major consequences on the timing of agricultural practices, with a change from autumn to spring-sown crops (Stoate et al. 2001). Lesser kestrel within irrigated landscapes selects alfalfa fields, particularly after harvest, strongly avoiding spring-sown maize fields (Ursua et al. 2005). Wine grapes are food for many wildlife species (Stavrinidis & Anayiotos 2006), such as the hare, especially in the August-September dry period when other food supplies are limited (Sokos & Andreadis 2000). ...
Falcons show fine anatomical and physiological adaptations to capture different kinds of prey, but the mean prey mass correlated positively with mean mass of the falcon. The proportion of birds affect the diet breadth at species level, and the proportion of invertebrates negatively correlate with the rate of mammals. Thus, mammalian-eating falcons able to switch to alternative prey, and bird-eating falcons are forced to enlarge their foraging area to find enough avian prey. Ultimately, prey size and the type of prey increase the reversed size dimorphism (RSD) of falcons from insects to mammals to birds as prey. Falcons show a certain dietary plasticity due to environmental conditions that limit the distribution of prey and their abundances. The food composition can differ significantly depending on the season and falcons adjusted hunting efforts and techniques accordingly. In addition, the breadth of the food niche was positively correlated with habitat heterogeneity that ultimately increases the number of prey species, especially birds. Hunting techniques adopted by falcons depend on prey size and prey type, and their availability is mainly related to variable environmental factors. Anyway, they prioritize saving energy when foraging than time spent during foraging bouts. Avian predators are one of the major factors modifying avian and mammalian prey assemblages of a territory. Spatial synchrony in rodent population fluctuation is well described at boreal ecosystem and also in Central Europe but at a large spatial scale. Falcons that exclusively exploit migrating small birds for rearing young need to move to their breeding areas every year and then leave these areas outside the breeding season due to the absence of alternative prey out the seasonal migration periods. Flocking, vigilance, and mobbing are adopted by prey against falcons’ attacks, but hunting success of falcons is highest in attacks on small flocks. Populations of specialist predators often fluctuate with populations of preferred prey species. For example, stable, regular, synchronous, 10–12-year quasi-cycles have been demonstrated in grouses and gyrfalcons.
The precise timing of reproduction is an important determinant of fitness of falcon. Increasing day length stimulates several neuroendocrine and endocrine secretions and triggers gonadal development in the anticipation of the breeding season. The female falcon starts egg formation after the achievement of body reserves that loss later during the early nesting period. The advance of laying time of falcons depends on the food supply in winter and spring, the amount of precipitation at that time of the year, and the spring temperatures. A breeding population consists of (1) breeding individuals of previous years, (2) first year individuals from the same area and (3) floaters. Floaters have a fundamental role on population growth, especially in small size populations. The decision of where to breed exerts a strong impact on fitness. Nevertheless, where nest sites are largely available without a concomitant food increase during the mating period, the number of breeding pairs does not increase. Overall, the cost of reproduction reduces subsequent survival and reproduction of parents that raise large number of offspring. Falcons changed eyries after successfully raising large broods, and eyrie switching increased the breeding success of females but not of males. An adaptive decline in average fertility, clutch size, and hatchability with progressive date of laying is characteristic of most bird species with a single clutch of variable size per year such as falcons. Successful individuals vary greatly in productivity, which is correlated with life span. Parental daily energy expenditure is positively associated with the increasing number of young in the brood. Male parents responded to brood size variation and adjusted their provisioning behaviour accordingly. Females show a conservative strategy aimed at maintaining and rationalizing fat reserves collected during the pre-reproductive phase. The post-fledging dependence period is the crucial stage when juveniles are still dependent from parents and move around the nest site with the family which occurs from the fledging day to the first of leaving the natal area. Reproductive performance of both sexes improved with age. In females this is due to a strong selective pressure upon non-competitive breeders, whereas males improve within individuals early in their life along with hunting skill.
La intensificación agraria a través del regadío, la mecanización y la aplicación de fertilizantes y pesticidas han incrementado enormemente el rendimiento agrícola en los últimos 40 años, proporcionando en la actualidad alimento a más de 6.000 millones de personas. No obstante, este proceso lleva aparejados una serie de costes ambientales que suponen una importante amenaza para la biodiversidad. A escala mundial, la intensificación agraria es considerada la mayor causa de extinción entre las aves, y existen evidencias que sugieren que existen impactos negativos sobre otros taxones (artrópodos y plantas). Aunque España mantienen uno de los sistemas agrarios menos intensificados de Europa, está previsto que en los próximos años la superficie de regadío aumente en 500.000 hectáreas, de las que 110.000 pertenecen a Castilla y León. El impacto del regadío sobre las poblaciones de plantas y animales ha sido escasamente cuantificado hasta el momento, realizándose bien de forma correlacional (no experimental), bien sin considerar una amplia variedad de taxones simultáneamente en la misma área. Desde finales de 2006, la Junta de Castilla y León y el Ministerio de Educación y Ciencia han financiado una investigación en la comarca de Payuelos, León, destinada a cuantificar el efecto potencial de la transformación agraria de 45.000 hectáreas de suelo agrícola sobre la biodiversidad de la flora y la fauna (insectos, micromamíferos, lagomorfos y aves). Estos grupos serán analizados tanto en el área experimental que está siendo transformada en regadío como en otras tres zonas con diferentes prácticas agrícolas que actuarán como controles; una dedicada al regadío intensivo desde hace más de 20 años y otras dos áreas extensivas de secano con diferentes sistemas de gestión agrícola y distintos grados de protección medio natural. El estudio ha sido diseñado para identificar y determinar la contribución relativa de diferentes factores relacionados con las prácticas agrarias, medidos a escala local (in situ) y de paisaje (por teledetección), que explican los patrones de biodiversidad. El objetivo último es la propuesta de una serie de medidas de gestión agrícola que permitan mitigar los efectos negativos de la intensificación agraria, de forma que este tipo de agricultura sea compatible con un adecuado mantenimiento de la biodiversidad. En la presente comunicación se describe tanto las líneas de investigación desarrolladas en el proyecto como los primeros resultados del estudio.
Technological advances for wildlife monitoring have expanded our ability to study behavior and space use of many species. But biotelemetry is limited by size, weight, data memory and battery power of the attached devices, especially in animals with light body masses, such as the majority of bird species. In this study, we describe the combined use of GPS data logger information obtained from free-ranging birds, and environmental information recorded by unmanned aerial systems (UASs). As a case study, we studied habitat selection of a small raptorial bird, the lesser kestrel Falco naumanni, foraging in a highly dynamic landscape. After downloading spatio-temporal information from data loggers attached to the birds, we programmed the UASs to fly and take imagery by means of an onboard digital camera documenting the flight paths of those same birds shortly after their recorded flights. This methodology permitted us to extract environmental information at quasi-real time. We demonstrate that UASs are a useful tool for a wide variety of wildlife studies.
The diets of Falco amurensis and F. naumanni were investigated by analysing the respective stomach contents of 64 and 22 individuals killed during a severe thunderstorm in December 2004. Interpretations of diet were made by considering (1) biomass of dietary items and (2) presence/absence of dietary items in the stomachs analysed. A single beetle (Coleoptera) species, cf. Heteronychus arator, made up the majority of stomach contents when using both methods. Other Coleopteran taxa did not comprise a significant proportion of the biomass in each stomach but were well represented in the stomachs of many individuals. Taxa less represented included Rodentia, Solifugae, Orthoptera, Hymenoptera and other unidentified prey items. Although both F. amurensis and F. naumanni sometimes feed on birds, we believe that all feathers found in stomachs were ingested during preening activities or were accidentally introduced during excision. The presence of a single beetle species in the diet of both species demonstrates the importance of episodic and/or predictable arthropod irruptions as a food source for these two migrant falcon species. Similarity in the stomach contents of both species indicates that both may face similar threats with regards to pesticide exposure, habitat alteration and persecution in their austral non-breeding range.
Weather conditions and landuses are factors of major interest in the population
dynamics of many farmland species. Due to human activities, both weather and
landuses vary more and more quickly. This may be considered as a main threath for
endangered species. That is the case of the Lesser kestrel, currently absent in many
European countries such as Hungary and Poland, where it was a common species. In
Spain the population was estimated in 20000-50000 pairs during the seventies, and
estimations droped till 4000-5000 pairs in the National census of 1989. Population
dynamic in Andalusia (South of Spain) is characterized by a low productivity due to
starvation of growing chicks. This is especially relevant during dry years. In this
scenario, it is appropiate to evaluate the effect of annual weather conditions and
landuse composition on the breeding success of the species, which are the main
objetives of this work. To do that we monitored six colonies during a variable period of
7-15 years with a constant effort. The relationship between annual weather conditions
and breeding success was quantified in all the colonies. Once we know how weather
influences breeding success, it was possible to predict the productivity of colonies by
using weather data from 1965 to 2000 and evaluate the population trend during this
period. We also evaluate the effect of landuse composition on breeding parameters
taking into account the possible masking effect of weather. Since landuse composition
probably influences lesser kestrel productivity by means of prey availability, we quantify
the prey densities in the most important land uses of the area. In addition we evaluate
whether the breeding success variability of colonies held any relationship with the diet
composition. A simulation model was also built to identify the main factors that link
landuse composition with breeding success.
The lesser kestrel Falco naumanni is a globally threatened species, whose breeding populations seem to have declined due to recent agricultural changes. However, nothing is known about habitat requirements during winter, despite the fact that several populations are overwintering in areas affected by agricultural transformations. We studied population size and habitat selection by wintering lesser kestrels in a Spanish pseudosteppe (Los Monegros), where traditional fallow systems for cereals are rapidly being replaced by intensive and/or irrigated crops. About 15% of the adult population wintered in the study area, as determined by systematic roadside counts compared with accurate censuses made during the breeding season. Wintering lesser kestrels preferred to forage on field margins and stubble, while avoiding abandoned fields, ploughs, scrubland, growing cereals and, mainly, the expanding irrigated crops. This work confirms the need to incorporate the habitat requirements of threatened species over their complete annual cycles; while breeding lesser kestrels scarcely use fallow (ploughed at that time), during the winter, fallow (stubble at that time) is their main foraging habitat. Both fallow land and the present agricultural calendar should be maintained to assure the conservation of wintering lesser kestrel populations.
Mate-feeding was studied at 13 nests in a colony of Lesser Kestrels Falco naumanni. Additionally, the seasonal variation in body mass of males and females was investigated throughout the breeding cycle. On average, mate-feedings (n = 783) began 54 d after the pair's first copulation and 16.5 d before the laying of the first egg, and lasted 23.7 d. Body mass of females increased from the beginning of the mate-feeding period and peaked at egg-laying. Males' body masses were less variable and tended to decrease from the mate-feeding period to the end of the breeding cycle. Our results suggest that mate-feeding is not relevant to pair formation, although it cannot be discounted that this behaviour may be important in tightening the pair-bond. The most evident function of mate-feeding in the Lesser Kestrel seems to be to increase the female's body mass, possibly to allow the laying of earlier and larger clutches. In fact, the start of the mate-feedings was correlated with laying date, and the earlier the laying, the larger the clutch.
The lesser kestrel Falco
naumanni is a cavity-nesting falcon that breeds colonially in steppe-like habitats. Circum-Mediterranean populations declined sharply during the 20th century and the species is categorized as Vulnerable on the IUCN Red List. We investigated the numbers of breeding pairs in Kazakhstan, previously considered to be an important area for the species, where it still inhabits natural steppe and semi-natural grasslands and breeds on cliffs. The availability of cliffs for nesting does not seem to be limiting as most cliffs are unoccupied. However, lesser kestrels tended to breed on small cliffs, where larger predatory raptors are scarcer. Abundance of lesser kestrels was also related to land use. Cliffs in semi-natural grasslands were apparently preferred over those in natural steppe, while those in agricultural landscapes were avoided despite the lower presence there of larger raptors. Large-scale transformation of steppe and grasslands into intensive agriculture might have reduced lesser kestrel numbers, and with the development of new agricultural projects, monitoring and conservation programmes for lesser kestrel populations are urgently required in Kazakhstan.
Research conducted in several Mediterranean areas indicates that most populations of steppe birds are currently experiencing population declines associated with intensification of traditional agricultural practices. By using habitat suitability modeling (HSM), our aim was to use available environmental data sets, including land use and relief, to model the current distribution of nine steppe bird species in the agriculture dominated areas of the Catalan Ebro basin (northeast Iberia). We then employ HSM to quantitatively assess the future impact of land use changes on the potential distribution range of these species under two scenarios following irrigation of present extensive cereal steppes in the area. HSM analyses showed a close association between steppe bird distribution and the extent of extensive cereal agriculture in flat areas. Although the sensitivity to planned irrigation schemes was species specific, we estimated significant decreases in distribution after irrigation for seven of the nine species examined, i.e. the Little bustard, the Montagu's harrier, the Roller and the Calandra lark, the species predicted to be more severely affected by predicted decreases in area exceeding 50%. Overall, core steppe habitats where most valuable steppe species may co-occur are expected to be mostly impacted and decrease by 74 to 81% after irrigation of only 28 to 36% of the cereal cropland in the region. Future maintenance and survival of viable populations of steppe birds will rely on our ability to enlarge the network of protected areas and to implement agri-environmental measures targeting current species core habitats in low-intensity farmland.
In mosaic landscapes, patch use by animals may depend on features associated with neighbouring patches, e.g. resources or predators. This is of concern for species living in fragmented remnants of natural habitats surrounded by man-modified habitats. We studied how landscape context influenced habitat use by a lekking grassland bird, the little bustard, in a landscape where protected patches of natural steppe were interspersed with improved pastures suitable to bustards, and other unsuitable habitats. At a scale equivalent to a lekking site (30–70 ha), the abundance of displaying males and nesting females on steppe plots increased with increasing availability of improved pastures within 1 km of plots. This concentration of breeding bustards on steppe habitat around modified pastures may partly result from the species' lekking system. We emphasize that increasing the suitability of managed habitats around protected natural areas may help in maintaining viable populations of native species by providing additional resources or breeding sites.
Roughly 20% of the European Union's farmland is under some form of agri-environment scheme to counteract the negative impacts of modern agriculture on the environment. The associated costs represent about 4% (1.7 billion euros) of the European Union's total expenditure on the Common Agricultural Policy and are expected to rise to 10% in the near future. Although agri-environment schemes have been implemented in various countries for well over a decade, to date no reliable, sufficiently replicated studies have been performed to test whether such measures have the presumed positive effects on biodiversity. Here we present the results of a study evaluating the contribution of agri-environment schemes to the protection of biodiversity in intensively used Dutch agricultural landscapes. We surveyed plants, birds, hover flies and bees on 78 paired fields that either had agri-environment schemes in the form of management agreements or were managed conventionally. Management agreements were not effective in protecting the species richness of the investigated species groups: no positive effects on plant and bird species diversity were found. The four most common wader species were observed even less frequently on fields with management agreements. By contrast, hover flies and bees showed modest increases in species richness on fields with management agreements. Our results indicate that there is a pressing need for a scientifically sound evaluation of agri-environment schemes.
The populations of farmland birds in Europe declined markedly during the last quarter of the 20th century, representing a severe threat to biodiversity. Here, we assess whether declines in the populations and ranges of farmland birds across Europe reflect differences in agricultural intensity, which arise largely through differences in political history. Population and range changes were modelled in terms of a number of indices of agricultural intensity. Population declines and range contractions were significantly greater in countries with more intensive agriculture, and significantly higher in the European Union (EU) than in former communist countries. Cereal yield alone explained over 30% of the variation in population trends. The results suggest that recent trends in agriculture have had deleterious and measurable effects on bird populations on a continental scale. We predict that the introduction of EU agricultural policies into former communist countries hoping to accede to the EU in the near future will result in significant declines in the important bird populations there.
The selection of foraging habitats by nine radio-tagged adult lesser kestrels (Falco naumanni) breeding in one colony in southern Spain, was studied in 1989 and 1990. Despite individual differences in the feeding habitat, there was a general tendency for grassland to be used more, and sunflower and woodlots to be used less, than expected by their availability. 2. The relatively higher food availability (measured as the number of hovering bouts by the lesser kestrels to catch one prey) of grasslands and cereals would explain the kestrels' preference for these habitats. 3. Since the 1950s, uncultivated grasslands in the area have decreased drastically and have been replaced by new crops, such as sunflowers. If grasslands continue to decrease in southern Spain, the progressive decline of lesser kestrel populations will probably continue in those areas.
Habitat and potential prey around 21 settlements with lesser kestrel Falco naumanni colonies and nine without in central Turkey were sampled in July 1994. The results suggested that lesser kestrel colonies were most commonly associated with dry and wet grasslands. Lesser kestrel colony size was also correlated with lizard numbers, and these may be an important prey. Further research on feeding ecology is important. The conservation of remnant dry and wet grasslands and marshes is a priority. The value of conservation headlands because of the prevalence of short-rotation arable agriculture should be investigated.
Maintaining winter stubble for the conservation of steppe passerines is widely implemented under the regional agri- environmental program in Spanish dry lands. The adequacy of such measures was assessed in terms of bird density on different soil cover types in central Spain. Highest bird densities were found in ploughed, sown and fallow plots. Stubble plots were poorly used by wintering passerines compared to other soil cover types. The maintenance of stubble should be therefore reconsidered as an agri-environmental commitment in the Spanish programs. © 2004 Elsevier B.V. All rights reserved.
Summary 1. We model the effect of annual weather conditions on lesser kestrel Falco naumanni breeding success in South-western Spain. Models indicate that rainfall is a good predictor of breeding success and has in general a positive effect on reproduction. 2. Rainfall and temperature in spring, during the courtship period, influence colony occupancy rate. Mean minimum temperatures have a positive effect on nest occupation while the relationship between occupation and rainfall is curvilinear with an optimum around 84 mm. 3. Nest success rate is influenced positively by rainfall in winter and negatively by rainfall during the nestling period. 4. The mean number of chicks per successful nest is positively influenced by rainfall during the winter, arrival, courtship, and incubation periods. Rainfall during these periods explains 35% of the variance in this breeding parameter. 5. Nestling body condition is affected positively by rainfall during the courtship and incubation periods. 6. Models that consider the amount of rainfall at each colony in periods defined by the breeding phenology of the lesser kestrel outperform those based on total annual rainfall or on winter NAO-index. 7. Although rainfall in spring has declined significantly since 1966, retrospective pre- dictions of lesser kestrel population growth rate at our colonies indicate that the effect of climate change on breeding success cannot be held responsible for the historical population decline.
The population decline of the lesser kestrel, a globally threatened species, has been sometimes explained on the basis of interspecific competition and lack of suitable nest-sites. Our results from a three-year study of 674 kestrel colonies in northeastern and south Spain showed that nest-site cavities were not a scarce resource even in decreasing populations. The presence of presumptive competitors (jackdaws Corvus monedula and feral pigeons Columba livia) did not limit nest-site availability. Breeding success was not lower in colonies with competi-tors than in colonies where the species breeds alone. We conclude that neither the lack of cavities nor the effects of interspecific competition can satisfactorily explain the global decline of lesser kestrel populations. Copyright © 1996 Elsevier Science Lhnited
Summary 1. Predictive models of species' distributions are used increasingly in ecological studies investigating features as varied as biodiversity, habitat selection and interspecific competition. In a pilot study, we based a successful model for the great bustard Otis tarda on advanced very high resolution radiometer (AVHRR) satellite data, which offer attractive predictor variables because of the global coverage, high temporal frequency of overpasses and low cost. We wished to assess whether the approach could be applied at very large spatial scales, and whether the coarse resolution of the imagery (1 km 2 ) would limit application to those bird species with large home ranges or to simple recognition of broad habitat types. 2. We modelled the distributions of three agricultural steppe birds over the whole of Spain using a common set of predictor variables, including AVHRR imagery. The species, great bustard, little bustard Tetrax tetrax and calandra lark Melanocorhypha calandra , have similar habitat requirements but differently sized home ranges, and are all species of conservation concern. Good models would reveal differences in distribu- tion between the species and have high predictive power despite the large geographical extent covered. 3. Generalized additive models (GAMs) were built with the presence-absence of the species as the response variable. Individual species' responses to the habitat variables were identified using partial fits and compared with each other. We found that this modelling framework could successfully distinguish the habitats selected by the three species, while the response curves indicated how the habitats differed. Model fits and cross-validations assessed using receiver operating characteristic (ROC) plots showed the models to be successful and robust. 4. We overlaid the predictive maps to identify key areas for agricultural steppe birds in Spain and compared these with the present network of protected sites in two sample regions. In Castilla León the provision of protected sites appears appro- priate, but in Castilla La Mancha large areas of apparently suitable habitat have no protection. 5. These results confirm that large-scale models are able to increase our under- standing of species' ecology and provide data for conservation planning. AVHRR imagery, in combination with other variables, has sufficient resolution to model a range of bird species, and GAMs have the flexibility to model subtle species-habitat responses.
Summary • Factors governing dispersal rates have seldom been examined in spatially structured populations of vertebrates. We gathered information during 8 years on transfer rates between subpopulations in a spatially structured, growing population of colonial lesser kestrels Falco naumanni, and analysed the contribution of several variables related to spatial isolation and characteristics of both subpopulation of origin and destination on probabilities of dispersal. • Lesser kestrels were highly philopatric to their subpopulations, but first-breeders dispersed more often than adults (26% vs. 4%, n= 1706) because adults were reluctant to move from familiar areas. Frequency of subpopulation change was higher in females than in males (first-recruiters: 30% vs. 22%, n= 987; adults 5% vs. 1%, n= 719), according to their different breeding roles. However, all populational factors had an equal effect on individuals of different sex and dispersal status. • Movement rates decreased with inter-subpopulation distance – indicating that travelling to distant subpopulations may impose costs in terms of breeding prospects – and with the number of subpopulations, which increased during our study period. • Conspecific attraction strongly influenced the probability of dispersal: it was relatively higher in largely populated subpopulations, and individuals of large subpopulations were reluctant to change to others. These results were neither influenced by the size and breeding density of the subpopulations nor by habitat quality in terms of food availability or risk of predation, as indicated by breeding success of kestrels at each subpopulation. The number of conspecifics could be used by the kestrels as a cue of patch quality in terms of settlement options, and large subpopulations could be more easily detected by prospecting birds. • Our study highlights the fact that several assumptions of theoretical metapopulation modelling are often not fulfilled in nature. Both theoretical models and management strategies on spatially structured populations or metapopulations should thus consider the number, population size, and spatial distribution of local populations, as well as their relationships with the dispersal ability of the species.
1. Agricultural land devoted to low-intensity practices supports many declining bird species in Europe. The potential effects of intensification or abandonment of traditional farming practices are assessed from the point of view of the conservation of the chough Pyrrhocorax pyrrhocorax.
2. The study was conducted in Los Monegros (north-east Spain), in a pseudosteppe landscape of special relevance for this species. In this area traditional farming survives in the form of low-intensity arable systems including fallowing and extensive sheep grazing.
3. Foraging choughs showed a strong selection for field margins, avoided any remnant of the original scrubland and halophitic vegetation, and utilized other habitats maintained by traditional crop rotation (e. g. fallow, stubble) at different times of the year.
4. A highly complex pattern of habitat selection was found which was not only related to seasonal changes in habitat availability, but also differed between territorial pairs and the non-breeding population. This emphasizes the importance of taking all the different components of bird populations into account when analysing interactions between habitat selection and the annual farming cycle.
5. Chough habitat selection suggests that both agricultural intensification and land abandonment would have detrimental consequences for this species in Los Monegros. The maintenance of traditional farming is recommended, especially by promoting the use of long fallow rotations grazed extensively by livestock, encouraging the increase of grassland edges around landholdings and sand roads, and maintaining a low input of biocides. These management measurements could also favour most other endangered species of steppe birds, and could be supported by the establishment of Zonal Programmes under the CAP Agri-Environment Regulation (2078/92).
European pseudo-steppes have suffered from extensive changes in agricultural practices during the past decades with the disappearance of field margins and fallow systems and the increase of biocide treatments. The negative effect on wildlife has led to the adoption by the European Union of policies more compatible with environmental conservation, but decisions about optimal land use are difficult to make because of lack of information. We studied habitat use by the Lesser Kestrel (Falco naumanni), a globally vulnerable species, in a Spanish pseudo-steppe (Los Monegros) where traditional agro-grazing systems are still being practiced, and we compared the results with those of another Spanish pseudo-steppe where modern and intensive agriculture has been implemented. We focused on the use by Lesser Kestrels of habitats subject to changes provoked by recent agricultural policies. Habitat availability was determined in a 3-km radius around 11 colonies, where 23 Lesser Kestrels were radio-tracked during the chick-rearing stage. Habitat selection was determined through compositional analysis. The rank of selected habitats was similar for all kestrels, considering both habitats surveyed and habitats where kestrels hunted. Kestrels selected field margins and cereal fields and rejected abandoned crops and scrubland. This selectivity seemed to be due to prey availability. In the intensively cultivated areas the kestrels selected similar habitats but used only small foraging patches and obtained smaller prey than in the traditional agro-grazing systems, probably because of the irregular distribution of prey resources as a result of the intensive biocide treatments. Consequently, in intensively cultivated habitats Lesser Kestrels had larger home ranges (63.65 km2) than in those with traditional systems (12.36 km2). These differences are reflected in the productivity and population trends of both populations. Thus, the best strategy for conserving the Lesser Kestrel seems to be the maintainance of traditional cereal cultures with low biocide treatments and numerous field margins. Both agricultural intensification and marginal land abandonment (with subsequent scrubland invasion) have detrimental consequences for this and probably for other pseudo-steppe species. Positive management steps can be encouraged by recent agro-environmental regulations such as the 2078/92 European Union Reglament, which favors the creation of programs in which agricultural practices accord with wildlife conservation.Conflictos Entre la Conservación del Cernícalo Priniilla y la Politica Agraria Comunitaria Determinados por Estudios Sobre Uso del HábitatDurante las últimas décadas, las prácticas agrícolas en las pseudo-estepas europeas han sufrido fuertes cambios; los márgenes entre campos y los sistemas de barbechado han tendido a desaparecer mientras se incrementaba el uso de biocidas. Estas tendencias se aceleraron con la puesta en marcha de la Política Agraria Comúniteria (PAC) de la Unión Europea (UE). Sus efectos negativos sobre la vida silvestre han determinado que la UE adoptara políticas más compatibles con la conservación del medio, pero las decisiones acerca del uso óptimo del suelo son difícles de tomar debido a la carencia de información. Nosotros hemos estudiado el uso del hábitat por el cernícalo primilla, una especie amenazada a nivel mundial, en una pseudo-estepa española (Los Monegros) donde se mantienen sistemas tradicionales agro-pastorales; los resultados se comparan con los obtenidos en otra pseudo-estepa española altamente transformada. Nos centramos en el uso de hábitats sujetos a cambios determinados por políticas agrarias recientes. La disponibilidad de hábitat se midió en torno a 11 colonias de cernícalo primilla, donde se siguieron mediante radiotelemetría 23 adultos durante la crianza de pollos, y su selección se determinó mediante el análisis composicional. El rango de los hábitats seleccionados fue similar en todos los individuos, tanto considerando la selección a nivel de hábitats prospectados como de hábitats donde obtuvieron presas. Los cernícalos seleccionaron márgenes de campos y cereales y evitaron campos abandonados y matorral; ello parece ser debido a diferentes rendimientos (disponibilidad de presas). En pseudo-estepas transformadas en áreas de cultivo intensivo los cernícalos seleccionaron hábitats similares pero sólamente usaban pequeñas parcelas para cazar, obteniendo presas de menor tamaño que en pseudo-estepas no alteradas; ello probablemente es debido a la irregular distribución de los recursos como consecuencia de los tratamientos con biocidas. Consecuentemente, en pseudo-estepas transformadas, los cernícalos primillas necesitaron áreas de campeo mayores (63,65 km2) que en aquellas con cultivos tradicionales (12,36 km2). Estas diferencias se reflejaron en la productividad y tendencias de ambas poblaciones. La mejor estrategia para conservar el cernícalo primilla parece ser el mantenimiento de los cultivos cerealistas tradicionales con bajos tratamientos y la potenciación de los márgenes entre campos. La intensificación de la agricultura y el abandono de tierras (con la subsecuente invasión de matorral) son negativos para ésta y probablemente para otras especies esteparias. Las medidas de manejo pueden incentivarse a través de las recientes regulaciones como el Reglamento 2078/92 de la UE que favorece prácticas agricolas respetuosas con la conservación de la fauna silvestre.
Cereal steppe habitat is a low intensive system that is rapidly disappearing as a result of changes in agricultural practices, and has the highest number of bird species with an Unfavourable Conservation Status of any habitat in Europe. A logistic regression model showed that the lesser kestrel, a globally threatened species, prefers to forage close to colonies, selects fields with livestock and avoids tree plantations. The conservation of this species is dependent on maintenance of extensive agriculture characterised by a rotation of cereal and grazed fallow. Abandonment of traditional agriculture and recent changes in agri-environmental programme support, which favour afforestation, are jeopardising the future of cereal steppes. Agri-environment measures are likely to be the most effective means of retaining the specific characteristics of cereal steppe habitat.
The Ebro Valley in Aragón (Spain) has practiced irrigation for approximately 2000 years, having one of the longest histories of continuous irrigation within Europe. Moreover, the only Aridisols in Europe occur in Spain, and Aragón contains a major portion of these soils. Remediation of soil problems associated with irrigation is needed to sustain agriculture and protect the environment. The region offers a great opportunity for scientists and engineers to gain knowledge and to conduct field experiments to solve aridity-related problems around the world. This article reviews the agricultural and environmental problems associated with irrigation in Aragón and possible solutions.
Environmental variables measured on 1:10,000 to 1:3,000,000-scale maps of southern Spain were used to build generalized linear models for presence/absence of lesser kestrel Falco naumanni colonies, extinction of colonies, and number of breeding pairs, in 6 × 6 km squares. Presence of breeding colonies in a square was positively associated with presence of urban areas, extent of non-irrigated cereal and sunflower crops, and mean annual rainfall, and negatively associated with extent of scrubland and forests. The model was statistically robust and had good predictive ability, correctly classifying 84% of the squares. Two alternative models were obtained for extinction of lesser kestrel colonies in a square. The first indicated extinctions where there were large areas of scrubland and low annual rainfall, and the second where there were very large or very small areas of non-irrigated cereal and sunflower crops. Although both were statistically significant, neither was very robust or had a good predictive ability. The number of lesser kestrel pairs breeding in a square showed a negative relationship with altitude, area of forest, and irrigated cultures, and a positive association with total length of rivers and streams. This model was not very robust and explained only 30·3% of the variance in kestrel numbers.The models indicate that some climatic and land-use variables, as measured on the available maps, are good predictors of the presence of lesser kestrel colonies in southern Spain, but less good at predicting the probability of extinction of colonies or the number of breeding pairs.
The populations of farmland birds in Europe declined markedly during the last quarter of the 20th century, representing a severe threat to biodiversity. Here, we assess whether declines in the populations and ranges of farmland birds across Europe reflect differences in agricultural intensity, which arise largely through differences in political history. Population and range changes were modelled in terms of a number of indices of agricultural intensity. Population declines and range contractions were significantly greater in countries with more intensive agriculture, and significantly higher in the European Union (EU) than in former communist countries. Cereal yield alone explained over 30% of the variation in population trends. The results suggest that recent trends in agriculture have had deleterious and measurable effects on bird populations on a continental scale. We predict that the introduction of EU agricultural policies into former communist countries hoping to accede to the EU in the near future will result in significant declines in the important bird populations there.
Residues of organochlorines, polychlorinated biphenyls (PCBs), and heavy metals (mercury, cadmium, lead, copper and zinc) were measured in unhatched eggs of Lesser Kestrels (Falco naumanni) collected in southern Spain in 1988-1991. Although contaminants were detected in all eggs, the amounts were generally below levels known to have negative effects on reproduction. This is consistent with the relatively high hatching rate (about 80%) in the studied population. The nestling mortality was severe, however, apparently due to starvation. It cannot be discounted that pesticides had an indirect effect on the kestrel's breeding success by reducing the populations of prey.
Factores ambientales relacionados con el e ´xito reproductivo del cerní primilla. Cambio climá e intensifi-cació n agraria Dispersal within a spatially structurated population of lesser kestrels: a role of spatial isolation and conspecific attraction
- C Rodrí
Rodrí, C., 2004. Factores ambientales relacionados con el e ´xito reproductivo del cerní primilla. Cambio climá e intensifi-cació n agraria. PhD Thesis, University of Salamanca, Spain. Serrano, D., Tella, J.L., 2003. Dispersal within a spatially structurated population of lesser kestrels: a role of spatial isolation and conspecific attraction. Journal of Animal Ecology 72, 400–410.
Birds in Europe: their conservation status
- G M Tucker
- M F Heath
Tucker, G.M., Heath, M.F., 1994. Birds in Europe: their conservation status. BirdLife Conservation Series 3, Cambridge.
Adequacy of winter stubble maintenance for steppe passerine conservation in central Spain. Agriculture, Ecosystems and Environment, in press Large-scale habitat selection by agricultural steppe birds in Spain: identifying species-habitat responses using generalized additive models
- F Suá
- V Garza
- J J Oñ Ate
- Garcí
- E L La Morena
- A Ramí
- M B Morales
Suá, F., Garza, V., Oñ ate, J.J., Garcí de la Morena, E.L., Ramí, A., Morales, M.B., 2004. Adequacy of winter stubble maintenance for steppe passerine conservation in central Spain. Agriculture, Ecosystems and Environment, in press. Suá-Seoane, S., Osborne, P., Alonso, J.C., 2002. Large-scale habitat selection by agricultural steppe birds in Spain: identifying species-habitat responses using generalized additive models. Journal Applied Ecology 39, 755–771.
Conflicts between lesser kestrel conservation and European agricultural policies as identified by habitat use analyses
- Tella
Adequacy of winter stubble maintenance for steppe passerine conservation in central Spain. Agriculture, Ecosystems and Environment
- F Suárez
- V Garza
- J J Oñate
- E L García De La Morena
- A Ramírez
- M B Morales