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Conservation Status of Neotropical Raptors
Abstract
The Neotropical region is renowned for its avian diversity and birds of prey are not an exception. This region hosts one of the greatest species richness of raptors and includes in this list some of the most singular and flagship representatives, such as the Andean condor and the harpy eagle. Many of the raptor species ranging in this region are also listed as Threatened and Endangered by the UICN. Conversion and destruction of natural habitats, active persecution, poisoning and other human related causes are among the threats that these species face in this region. Here we examine and review raptor diversity and conservation in the Neotropics pointing gaps and future research needed aiming to preserve their populations.
... Raptors can be particularly sensitive to landscape changes produced by roads (Sarasola et al. 2018, O'Bryan et al. 2022, with habitat selection and use both affected (Dean and Milton 2009, Lambertucci et al. 2009, Planillo et al. 2015. In some cases, the changes are positive from raptors' perspectives; for example, novel elements associated with roads such as fences, power lines, and road signs can increase perching, nesting, and foraging sites (Meunier et al. 2000, Morelli et al. 2014, Planillo et al. 2015. ...
... Despite roads being some of the most threatening human infrastructures to Neotropical raptors (Sarasola et al. 2018), there is scarce information on the direct or indirect impacts that roads exert on raptor species in the region. We found that most of the road-killed raptors in central and northern Argentina involved facultative or obligate scavengers, particularly Crested Caracaras. ...
... This mortality source is responsible for declines in raptor populations on most continents (Eccleston and Harness 2018, Slater et al. 2020). However, this threat from human infrastructure has received little attention in the Neotropics despite the high raptor species diversity in the region (but see Ibarra andDe Lucca 2015, Galmes et al. 2018a), and the critical conservation status of many of those species (Sarasola et al. 2018). Compared to other regions, systematic studies of raptor electrocution are lacking (Lehman et al. 2007). ...
... Consequently, retrofitting a relatively small number of poles would likely have an outsized positive effect on the Chaco Eagle population. Of note is that among the many human-related threats that endangered raptors face in the Neotropics (Sarasola et al. 2018), mortality by electrocution has not been highlighted as one of the most significant, and has been documented only for the Chaco Eagle (Galmes et al. 2018a, this study) and for the Ridgway's hawk (Buteo ridgwayi) to date (Dwyer et al. 2019). Although power lines may not pose a risk to all raptor species, the lack of reports of electrocutions for other endangered or critically endangered species is likely a consequence of inadequate survey efforts at a regional scale. ...
Electrocution is a widespread conservation problem for birds of prey that has received little attention in the Neotropics. Here we present electrocution records involving the endangered Chaco Eagle (Buteogallus coronatus) in central Argentina, and we provide information on the power pole structural characteristics associated with electrocutions. Nine Chaco Eagles were recorded electrocuted during the period 2012–2019 over an area of 9000 km2. Chaco Eagles were found electrocuted in association with five types of power poles, but more than half the electrocutions (55%) were on poles made of steel-reinforced concrete and with jumper wires above the crossarms. With the addition of four previous electrocution reports in this region during the same time period, the annual rate of Chaco Eagle electrocutions was similar to the rate of mortality by other human-related factors such as direct persecution. Future conservation actions and research should focus on retrofitting the small fraction of poles that pose the highest electrocution risks for Chaco Eagles, and on assessing the demographic effects of electrocution mortality for this species and other endangered raptors in Argentina.
... Another book that is similar to this one, but focused mainly on diurnal raptors, is Sarasola et al. (2018b). That edited volume also contains chapters on topics highlighting regional patterns of conservation concern including those focused on raptors in Asia (Concepcion et al. 2018), Africa , and the Neotropics (Sarasola et al. 2018a). Some of the authors of those chapters also authored chapters in this volume. ...
Many of the world’s raptors, or birds of prey, are experiencing declines and are increasingly threatened with extinction. The State of the World’s Raptors provides a novel approach for setting priorities for the conservation of raptors across the globe. Biologists from The Peregrine Fund, the US Geological Survey, and the Zoological Society of London divided the world into 14 raptor conservation regions. They then determined priorities for raptor conservation based on the evolutionary distinctiveness and extinction risk of the species that occur in each region. Priorities for each raptor conservation region were documented in separate chapters, each of which was led by local raptor experts. The State of the World’s Raptors thus provides regional perspectives on global priorities to save raptors from extinction.
... Effective conservation strategies addressing human-raptor conflicts are urgently needed to mitigate such decreasing raptor populations both on the local and global scales (Cruz, Santulli-Sanzo, and Ceballos 2021;McClure et al. 2018). Although raptor diversity peaks in the tropics and developing countries harbor the highest number of raptor species (Cruz, Santulli-Sanzo, and Ceballos 2021;McClure et al. 2018;Sarasola, Grande, and Bechard 2018), there are few active conservation strategies to conserve tropical raptors. In particular, raptor conservation strategies are scarce in rural areas, where conflicts between human and raptor populations are more latent (Garzón Freire 2017;Restrepo-Cardona et al. 2020). ...
Ethnoscientific approaches offer valuable tools for exploring human–nature relationships, making them useful for developing effective conservation strategies. Raptors, which are birds of prey, face significant conservation threats worldwide, with human persecution being a leading factor in their population decline. Urgent conservation strategies are needed, particularly in regions of high raptor diversity like the tropical Andes. In this study, we employed semistructured questionnaires and logistic models to investigate how demographic factors, economic activity, and traditional knowledge shape people's perceptions of raptors in rural communities of the Ecuadorian Andes. These communities have historically experienced poverty and inequality, and our approach takes into account their local realities to provide conservation recommendations. Our findings reveal that traditional ecological knowledge provides a broad understanding of human–raptor relations, and that raptors are viewed as both providers of ecosystem services and disservices. Additionally, social demographics, such as gender and educational level, can influence people's perception of raptors. Based on these results, we can promote conservation actions from a local to global level. Ethnoecological approaches offer diverse conservation opportunities that can vary based on different local contexts. In addition to conventional measures such as environmental education programs, poultry management, and landscape preservation, it is essential to consider the political ecology of specific sites, particularly in regions of the Global South where poverty and inequality are closely intertwined with social and environmental injustices. As such, policy making to alleviate poverty and inequality in rural communities in Ecuador and other Andean countries; and science decolonization to make conservation more inclusive are crucial for human well-being and successful and lasting conservation actions for raptors and biodiversity.
... These are of great concern in the case of threatened species and those with declining populations that could be rapidly eliminated at the landscape scale as a result of these conflicts (Zimmermann et al., 2021). Human persecution to mitigate or prevent the predation of domestic animals is an important threat to Neotropical eagles, especially those of larger size (Sarasola et al., 2018). For example, human persecution of the Harpy Eagle (Harpia harpyja) in Brazil is an important threat to the species (Miranda et al., 2021) and such persecution constitutes a relevant threat to the Chaco Eagle (Buteogallus coronatus) in Argentina (Barbar et al., 2016). ...
Background and Research Aims: The Black-and-chestnut Eagle (Spizaetus isidori) has a total population of fewer than 1000 adult individuals, and is categorized as Endangered at the global level. The northern Andes (Ecuador and Colombia) represent one of the last population strongholds of the species. In this study, we analyzed human persecution of the Black-and-chestnut Eagle as retaliation or as a preventive measure against poultry predation, as well as other threats that have affected the species in this geographical region between 2000 and 2022.
Methods: In order to understand the human persecution and other threats faced by the Black-and-chestnut Eagle in the northern Andes, we compiled records of immature and adult individuals of the species that had been shot, captured, or had
presented evidence of any other affectations during the last 23 years. Results: We found a total of 96 Black-and-chestnut Eagles affected by different threats. Human persecution of the species to prevent poultry predation was the motive in 81% (46 of 57) of the cases of shot eagles, 67% (10 of 15) of those captured illegally, 30% (3 of 10) of those in which the cause of affectation was undetermined and for one individual that had been stabbed. Immature eagles were more affected than adult eagles by human persecution. Black-and-chestnut Eagles were also affected by
electrocution, illegal trafficking and collision with vehicle. Conclusion: Human persecution as retaliation or as a preventive measure against poultry predation is an important threat to the conservation of the Black-and-chestnut Eagle in northern Andes. Implications for Conservation: Strict application of laws at human persecution sites, identification and monitoring of areas with high risk of human-eagle conflict, development of environmental educational programs, strengthening of the technical capacities of rural communities, maintaining or even increasing forest cover, and reducing the exposure of poultry by using enclosures are key for Black-and-chestnut Eagle conservation in the northern Andes.
... Our study demonstrates the critical nature of forests and farmlands, which are home to over 90% of all raptor species recorded in the study area. Forests, as raptor habitats, are more vulnerable and hence demand conservation and effective protection [15,151,152]. Seven species, mostly residents, were identified across all landscape types being resilient to or having acclimated to landscape changes throughout time [12]. Given that food availability is a significant determinant of raptor density [17], the distance from dumping sites reduces human-subsidized food availability, thereby negatively affecting the raptor population. ...
Raptors are highly sensitive to environmental and human-induced changes. In addition, several species of raptors exist in considerably small numbers. It is thus critical to conserve raptors and their habitats across relatively larger landscapes. We examined the diurnal raptor assemblages and seasonality in a subtropical habitat in India’s northwestern Himalayas. Quantitative data on diurnal birds of prey and their habitat features across six distinct habitat types were collected from 33 sample sites. We observed 3,434 individuals of 28 diurnal raptors belonging to two orders and three families during a two-year survey from December 2016 to November 2018. A significant variation in bird species richness and abundance was found across habitats and seasons, with farmlands and winters being the most diverse and speciose. The generalized linear model, used to determine raptor community responses, indicated that elevation and proximity to dumping sites significantly affected the raptor abundance. The non-metric multidimensional scaling (NMDS) revealed significant differences in raptor assemblages across the habitat types. The study concluded that raptors’ persistence is largely determined by their preference for favourable feeding, roosting, and nesting opportunities. The presence of protected and habitat-exclusive species validates the high conservation importance of these ecosystems, particularly the forest patches and farmlands, necessitating robust conservation and management measures in this part of northwestern Himalaya.
... Raptor communities in the Neotropics are diverse and of both ecological and cultural significance (Sergio et al. 2006, Sarasola et al. 2018. Basic life history characteristics, such as breeding ecology and behavior, remain poorly known for many Neotropical raptor species because low breeding densities and secretive behaviors in dense rugged terrain make observations and scientific studies logistically challenging (Whitacre 2012). ...
Little is known about the breeding ecology of Hook-billed Kites (Chondrohierax uncinatus). This is the first study in Belize on this highly specialized, secretive, and uncommon Neotropical raptor species, which is showing a decreasing population trend according to the International Union for the Conservation of Nature. We monitored six Hook-billed Kite nesting attempts over a 3-yr period (2012–2014), presumably all involving the same pair nesting at a single location in the Cayo District of Belize, Central America. For each nesting attempt, we documented phenology, nest and nest-site characteristics, incubation and nestling periods, productivity, and diet. Of the six nests where eggs were observed, three had two eggs. Fledging production averaged 1.7 ± 0.5 (SD) young per nesting attempt. The male and female equitably shared incubation roles (male = 49%, female = 51%) and hunted to feed themselves during the incubation period, which is uncommon in raptors. The nestling period ranged from 20–27 d between 3 May and 18 October. Fledging coincided with or occurred after the onset of the wet season. Prey delivered to the nests comprised two species of arboreal land snails: Orthalicus princeps (99%) and Euglandina ghiesbreghti (1%). Three of the six nesting attempts occurred consecutively in 2014 and produced a combined total of five fledglings (first and third attempts fledged two young and second attempt fledged one young). This represents the first observation of successful triple brooding among Hook-billed Kites during a single breeding season. Triple brooding rarely occurs among raptors and more typically follows early nesting failure. Understanding the basic breeding biology of Hook-billed Kites is important given their highly specialized ecology, which makes them especially vulnerable to climate change and habitat loss.
... Higher biodiversity levels were reported at sites occupied by the raptors than at the sites from which they were absent [3]. Major threats i.e., collision with man-made objects [4], poisoning [5], the pressure of the growing human population, and pollution [6], seem to be affecting raptor populations and their distribution. Threats also include widespread deforestation and other habitat alterations; use of pesticides to maintain food production and overgrazed arid and montane regions; and the essentially unknown element of hunting and trade [7]. ...
Diurnal raptors show a wider distribution compared to other groups of birds including passerines, woodpeckers, and seriemas, but occur at lower-than-expected densities. Estimating the precise abundance is essential to achieve conservation goals but the methods used to estimate the populations of birds need to be appropriate to arrive at meaningful conclusions. We compared the two survey methods: roadside point count and strip transects, for estimating species richness and abundance of raptors in the arid landscape of Rajasthan. Roadside point counts and roadside strip transects were done on 50 transects between December 2019- February 2020 (with an average length of 20 km and a total distance of 3000 km) to assess the species richness and abundance of raptors. A total of 2954 observations of raptors belonging to 35 species were recorded using both methods. Mann Whitney U test result showed no significant difference in species richness and abundance estimates between both methods (p = 0.206). The point count method yielded a higher relative abundance of 2.79 individuals [10 km²]⁻¹h⁻¹ than the 1.90 individuals [10 km²]⁻¹h⁻¹ obtained during the strip transect. Also, the number of unidentified species were less for point counts. Extrapolation values indicated that both the methods do not differ much for the detection of unsampled species. The choice of survey method depends on the objectives of the study, but our results favor the use of point counts rather than strip transects to survey raptors in open habitats. The information generated from this study is expected to provide the most efficient method to study the abundance and distribution of raptors in similar landscapes.
... Given the aforementioned forest destruction rates, it is no surprise that forest raptor species are more prone to be threatened or declining than those depending on other habitat types (McClure et al. 2018). Loss of old mature forests is causing declines in many forest species including raptors (Khaleghizadeh et al. 2014, Björklund et al. 2015, Ferrer-Sánchez and Rodríguez-Estrella 2015, Sarasola et al. 2018). However, some species have expanded their range by adapting to commercial forest plantations or urban gardens (Bird et al. 1996, Rosenfield et al. 2000, Malan and Robinson 2001, Sarasola and Negro 2006, Barrientos and Arroyo 2014. ...
Forest‐dwelling raptors living on islands are more vulnerable than continental relatives due to their particular life history traits and habitat degradation. The Canary Islands' forests have suffered severe transformations because of intense human exploitation since its colonization by the Europeans. In recent decades, forest managers have initiated actions to restore the original ecosystems. Consequently, gathering knowledge on the relationships between habitat and reproduction output of forest species is essential to develop long‐term conservation actions. Here, we explore the suitability of exotic tree plantations as breeding habitat for an island endemic raptor, the Macaronesian sparrowhawk Accipiter nisus granti. We monitored territories distributed in three main forest types, two native (laurel forest and Canarian pinewood) and one composed of exotic trees. We assessed breeding density, characterized nesting habitat at macro‐, micro‐habitat and nest tree levels, and estimated breeding parameters in the three forests. We evaluated habitat selection and its potential relationship with breeding parameters, as well as nest structure survival in native versus exotic tree species. Density was higher in exotic forests and habitat features differed among forests at three spatial scales. Sparrowhawks used areas with high cover of exotic trees, with high trees, far away from human settlements and at low altitudes. All models testing for differences in breeding success and productivity among the forest types were not significant, but the percentage of successful pairs was slightly higher in exotic tree plantations than in native forests. Nest structures located in exotic trees showed a higher annual survival than those placed in native trees. Our results indicate that exotic plantations are a secure nesting habitat and therefore forestry practices, including those aiming to eradicate exotic trees, must be carefully planned to avoid nest destruction or disturbance in occupied forest patches.
... Our study demonstrates the critical nature of forests and farmlands, which are home to over 90% of all raptor species recorded in the study area. Forests, as raptor habitats, are more vulnerable and hence demand conservation and effective protection [15,151,152]. Seven species, mostly residents, were identified across all landscape types being resilient to or having acclimated to landscape changes throughout time [12]. Given that food availability is a significant determinant of raptor density [17], the distance from dumping sites reduces human-subsidized food availability, thereby negatively affecting the raptor population. ...
Raptors are highly sensitive to environmental and human-induced changes. In addition, several species of raptors exist in considerably small numbers. It is thus critical to conserve raptors and their habitats across relatively larger landscapes. We examined the diurnal raptor assemblages and seasonality in a subtropical habitat in India’s northwestern Himalayas. Quantitative data on diurnal birds of prey and their habitat features across six distinct habitat types were collected from 33 sample sites. We observed 3,434 individuals of 28 diurnal rap- tors belonging to two orders and three families during a two-year survey from December 2016 to November 2018. A significant variation in bird species richness and abundance was found across habitats and seasons, with farmlands and winters being the most diverse and speciose. The generalized linear model, used to determine raptor community responses, indicated that elevation and proximity to dumping sites significantly affected the raptor abun- dance. The non-metric multidimensional scaling (NMDS) revealed significant differences in raptor assemblages across the habitat types. The study concluded that raptors’ persistence is largely determined by their preference for favourable feeding, roosting, and nesting opportunities. The presence of protected and habitat exclusive species validates the high conservation importance of these ecosystems, particularly the forest patches and farmlands, necessitating robust conservation and management measures in this part of northwestern Himalaya.
... Historically, it inhabited a wide range of lowland forests and forest enclaves at altitudes of 0 to 800 m, from the forests of southern Mexico to northeast Argentina (Miranda et al., 2019;Vargas-González et al., 2006). Globally, the harpy eagle is considered Near Threatened (Sarasola et al., 2018). It has been extirpated from habitats across Mexico and Central America and populations have decreased in South America due to the destruction, fragmentation and degradation of forests (Banhos et al., 2016;Miranda et al., 2019). ...
The harpy eagle (Harpia harpyja) is one of the main predators of arboreal mammals in the neotropics, affecting the ecology and behaviour these species. Knowledge of harpy eagle diets across their geographical range is patchy, the ability of harpy eagles to adapt to changing habitats is still open to question. The three main species in the diet of harpy eagles nesting at Tambopata were porcupines (Coendou sp.) (n = 7) howler monkeys (Alouatta sara) (n = 6) and two-toed sloths (Choloepus didactylus) (n = 4), all species that do well in disturbed forests. We conclude that harpy eagles can reproduce in secondary forests, feeding on abundant disturbance-tolerant species, if they themselves are not hunted and their nesting trees are conserved. Harpy eagle nests have a high value for tourism, and strategies that allow landowners to benefit from harpy eagles nesting on their property through revenues from tourism may be instrumental in incentivising the conservation of forests and emergent trees, and the regeneration of forests in anthropogenic landscapes.
... Collared Forest-falcon, Hook-billed Kite, Crane Hawk). Additionally, raptors are prone to human persecution, some species being particularly vulnerable because they are considered agricultural pests (Thiollay 1989a;Sarasola et al. 2018). In our study area, species such as the Gray Hawk, Great Black Hawk, and Laughing Falcon are perceived as predators of farmyard chickens, making them vulnerable to human persecution in the region (MMR pers. ...
Context
Theoretical models propose that the spatial extent at which landscape structure best predicts species responses (scale of effect, SoE) depends on habitat and dietary specialization, landscape metrics, and response variables. However, empirical support for such models is scarce, especially for apex predators.
Objectives
To determine SoE for diurnal raptors, and test for differences among ecological traits of habitat and dietary specialization, landscape metrics, and response variables.
Methods
We conducted 1.5 km transect surveys of diurnal raptors at 26 sites in a tropical dry forest from western Mexico. We measured four landscape metrics (forest cover, matrix hardness, forest patch density, edge density) in 16 concentric landscapes (400 to 3400 ha) around each survey site. We then assessed the landscape size at which each landscape metric best predicted each response variable (abundance, species richness, temporal beta diversity). Finally, we tested for differences in SoE among ecological traits of raptors, landscape metrics, and response variables.
Results
Landscape composition metrics of forest cover and matrix hardness decreased with increasing landscape size, and were the main landscape predictors influencing diurnal raptors. SoE differed significantly among landscape metrics, being larger for forest cover (2433.3 ha) than matrix hardness (1500 ha). However, SoE did not differ significantly among ecological traits of raptors, or response variables.
Conclusions
SoE was mainly driven by spatial metrics, with diurnal raptors being more strongly associated with forest cover measured over larger scales. This supports findings for other taxa and suggests that forest cover influences dispersal success across larger scales.
... Persecution might be the main threat to Neotropical raptors in the form of retaliation, or to prevent predation on domesticated animals [11]. As a consequence, the negative perception of raptors and the resulting actions against them can lead to the extirpation of populations or even to species extinction [12]. ...
In human-transformed landscapes, predators may feed on domesticated animals, and thus affect human well-being, creating negative perceptions and leading to conflict with people that can result in the persecution of the predator. We studied the factors that influence the perception of the Black-and-chestnut Eagle (Spizaetus isidori) in four rural Andean communities in Colombia and compiled historical and recent evidence on the persecution and other causes of mortality of this species in the country. We applied 267 questionnaires and conducted 16 interviews with local inhabitants, via visits to homes and schools in the surroundings of S. isidori nests. The perception of S. isidori by the inhabitants was largely negative and influenced by different socio-demographic factors such as gender, chicken (Gallus gallus) ownership, and chicken management. The records we obtained indicate that 47 eagles were shot, 16 were captured (three for illegal trafficking) and two were electrocuted on high-tension wires. The persecution of S. isidori occurs as retaliation or as a preventative measure against chicken predation, and is a significant cause of mortality of this species in Colombia. Effective conservation planning for S. isidori in Colombia needs to go further than the protected areas system, and include a socioecological perspective in conservation practices applied at landscapes scales that are dominated by people. Education programs and socioecological research, along with participatory work in local communities are key to the conservation of S. isidori in breeding territories. This approach can also prevent conflict over food resources—G. gallus and other poultry—that are shared by humans and S. isidori in rural landscapes.
... Many Neotropical raptors are considered uncommon or rare species, and the current status of a great percentage of them is of special concern because many will become rarer in the medium term (Ferrer-Sánchez & Rodríguez-Estrella, 2016), it has been estimated 46% are threatened by human transformation of native ecosystems (Sarasola, Grande, & Bechard, 2018). Furthermore, there is particular concern on the conservation of rare endemic island raptors because they are highly prompt to extinction, mainly those with a narrow distribution, narrow habitat tolerance, and small population size (Gaston & Fuller, 2009). ...
Raptor species conservation should consider a landscape perspective in order to include habitat requirements associated to large home ranges around nesting sites. Landscape analysis can help to better understand raptor habitat requirements and the degree of tolerance to habitat changes at different scales.
We used a landscape ecology perspective to determine the nesting habitat selection of endemic and endangered Cuban Black Hawk, and using ecological niche modeling, we obtained the potential distribution of nests to evaluate the effectiveness of protected areas (PAs) for raptor conservation.
Nesting habitat selection was related to breeding success at a landscape scale using data from 27 different nesting sites during 2012–2013 breeding seasons. The potential nesting areas distribution was compared with current officially PAs design in the central region of Cuba.
All nests were located in mangrove swamp. Pairs chose nesting sites with low soil–vegetation moisture and low soil reflectance. At the landscape level, they selected low shape complexity of patches and few patches of coastal vegetation around nesting sites which contained similar mangrove patch size and shape. The potential distribution of nests increased close to the coastline. The model predicted a suitable narrow area of 556 km², and the most favorable nesting area represented 2% of this total. 33% of nests were located within officially natural protected areas while 27% were close to or inside highly threatened areas. A 16% of high to medium suitable nesting habitat overlaps with urban areas. Currently, PAs contain 23% of the nesting area distribution.
Our study shows landscape ecology and nest‐site selection approach is crucial to evaluate the persistence of Cuban Black Hawk, as environmental variables and human activity can be related to its productivity. This approach can be applied in conservation strategies of island raptors.
... Collared Forest-falcon, Hook-billed Kite, Crane Hawk). Additionally, raptors are prone to human persecution, some species being particularly vulnerable because they are considered agricultural pests (Thiollay 1989a;Sarasola et al. 2018). In this sense, we believe that forest cover in the landscape should most strongly influence dispersal success for raptors by reducing mortality of individuals during the dispersal process. ...
The response of birds to hurricane disturbance may differ among functional groups, but little is known regarding the response of birds of prey to these disturbances. We aimed to evaluate the influence of Hurricane Patricia on the diversity of diurnal raptors in tropical dry forest in Mexico. We conducted raptor surveys at 13 sites located within the eyewall radius of maximum hurricane winds along the hurricane’s path, and 16 sites outside this area. We compared density and species richness among four habitats of deciduous and semi-deciduous forest, mangroves and agricultural fields, within the hurricane eyewall and outside the eyewall. We observed a reduction in raptor density in forests within the eyewall. Raptor density was significantly lower in deciduous forests within the eyewall compared to deciduous forests outside this area. Species richness was similar among habitats and conditions, but mangroves within the eyewall had significant higher species richness compared to mangroves outside this area. We found a significant increase in species evenness, and decrease in similarity of raptor communities in mangroves and deciduous forests within the eyewall, compared to mangroves outside the eyewall. Reduced density of raptors in forest within the path of the hurricane probably reflects the impact of winds on forest structure, whereas the increase in evenness and species richness in mangroves within the hurricane eyewall suggests that these habitats could provide refuge for raptors following hurricanes. Our results highlight the importance of maintaining landscape heterogeneity to provide alternate habitats for wildlife communities and facilitate their resilience following major disturbances.
... Further, forest species are more likely to be threatened and in decline than non-forest species. Our results thus compliment those of other authors who noted that forests are key to conserving the world's raptors (e.g., Bildstein et al., 1998;Mooney, 1998;Sarasola et al., 2018;Thiollay, 1998) and general biodiversity (Brooks et al., 2006). Of species that use forests, tropical raptors are more likely to be threatened and in decline than those (2016) assessments. ...
Raptors provide critical ecosystem services, yet there is currently no systematic, global synthesis of their conservation status or threats. We review the International Union for the Conservation of Nature's Red List to examine the conservation status, distributions, threats, and conservation recommendations for all 557 raptor species. We further assess the significance of Important Bird and Biodiversity Areas (IBAs) for raptor conservation. We also determine which countries contain the most species listed under the Memorandum of Understanding on the Conservation of Migratory Birds of Prey in Africa and Eurasia (Raptors MoU). Raptors, especially Old World vultures, are more threatened than birds in general. Eighteen percent of raptors are threatened with extinction and 52% of raptors have declining global populations. South and Southeast Asia have the highest richness and the largest number of threatened raptor species. By country, Indonesia has the highest richness of raptor species (119) and most declining species (63). China and Russia contain the most Raptors MoU species, although they are not yet signatories to the agreement. Raptor species that require forest are more likely to be threatened and declining than those that do not. Agriculture and logging are the most frequently identified threats, although poisoning is especially detrimental to Old World vultures. Of the 10 most important IBAs for raptors, six are in Nepal. Highest priority conservation actions to protect raptors include preventing mortality and conserving key sites and priority habitats. Improved long-term monitoring would allow for conservation to be appropriately targeted and effectiveness of interventions to be assessed.
Population genetics is an invaluable tool for studying and conserving scarcely researched and elusive threatened species. The Chaco eagle (Buteogallus coronatus) is one of the rarest and most severely threatened raptors in the Neotropical region, and due to its elusiveness, many aspects of the species’ life history, with important conservation implications, remain mostly unknown. Here, relying primarily on non-invasive DNA sampling at a large spatio-temporal scale, we investigate the reproductive strategies of the Chaco eagle. Over twelve years (2002–2014), we collected 87 moulted feathers from territorial individuals and blood samples from 32 nestlings at 30 nesting sites distributed across a large region (approximately 30,000 km2) of semiarid habitats in Argentina. A primary aim was to elucidate whether this species breeds on a two-year cycle basis, a crucial but still unclear aspect of its life history since, if confirmed, this delay would impose a significant limitation on the lifetime productivity of Chaco eagles across its entire range. We also investigated the occurrence of pair substitutions and territory changes between reproductive
events, factors likely intertwined with adult mortality rates and anthropogenic pressures. We found conclusive evidence that eagles may breed annually. In addition, our data suggest that the
replacement of a pair member and/or the breeding dispersal to another territory (up to 30 km away) is not uncommon in the species, presumably due to human-related mortality. These spatial patterns of breeding territory selection and breeding dispersal have never been described for large eagles in the Neotropics and highlight the potential ecological consequences of human pressure on this keystone species. Overall, these findings bear direct implications for the demographic dynamics, management, and conservation strategies of the Chaco eagle.
Background
In birds, the onset of dispersal is the transition point between the end of the post-fledging dependence period (PFDP) and the beginning of natal dispersal. Identifying this key moment in an individual’s life cycle is crucial for understanding the ecology and demography of a species, but its determination remains a challenge. Some methodologies used to estimate it usually yield biased outcomes, while others are based on adult ranging areas and require previous knowledge on the species’ movement patterns, precluding their use in little-known species. Additionally, the proposed methods have never been compared with data on family breakup timing. Thus, creating a standardized methodology, not based on species-specific information and with a reliable reference, to estimate the onset of dispersal for its use on a wider array of birds is key to optimizing research on rare and/or elusive species.
Methods
We used unique GPS data from parent Chaco eagles (Buteogallus coronatus), a large, territorial, and endangered species, with their corresponding fledglings during the PFDP as a reference against which to evaluate (1) the existing methodologies in the literature; (2) modified methods based on previous ones; and (3) new methods related to changes and overlap values in the ranging areas of young individuals. To quantitatively assess which method best matched the reference values, we calculated the mean deviation and bias on an individual basis, also accounting for the interindividual coefficient of variation.
Results
Most previously published methods assign the onset of dispersal prematurely, probably because they are sensitive to exploratory or foraging movements that young individuals perform prior to dispersal. The modified methods, although more accurate, still provided biased estimates. However, the new methods we propose provided estimates of the onset of dispersal with increased accuracy and low interindividual variability.
Conclusions
The new methods proposed (1) provide the most accurate estimates of the onset of dispersal; (2) are standardized, so they can be used for a wide range of bird species; (3) do not require previous knowledge of adult movement patterns; and (4) are very useful for most bird research studies that tag fledglings with GPS transmitters.
Conflicts between rural people and the Endangered Black-and-chestnut Eagle (Spizaetus isidori) are a prominent conservation concern in the northern Andes, as at least 60 eagles were poached between 2000 and 2022 in response to poultry predation. Here, we conducted direct observations to analyze the Black-and-chestnut Eagle diet and evaluated how forest cover affects the feeding habits of the species during nestling-rearing periods in 16 nests located in different human-transformed Andean landscapes of Ecuador and Colombia. We analyzed 853 prey items (46 species) delivered to nestlings. We used Generalized Linear Models to test whether the percent forest cover calculated within varying buffer distances around each nest and linear distances from the nest to the nearest settlement and pasture areas were predictors of diet diversity and biomass contribution of prey. Forest cover was not a factor that affected the consumption of poultry; however, the eagle regularly preyed on chickens (Gallus gallus) (i.e., domestic Galliformes) which were consumed by 15 of the 16 eagle pairs, with biomass contributions (14.57% ± 10.55) representing 0.6–37% of the total prey consumed. The Black-and-chestnut Eagle is an adaptable generalist able to switch from mammalian carnivores to guans (i.e., wild Galliformes) in human-dominated landscapes, and eagles nesting in sites with low forest cover had a less diverse diet than those in areas with more intact forests. Management actions for the conservation of this avian top predator require studies on the eagle’s diet in areas where human persecution is suspected or documented, but also maintaining forest cover for the wild prey of the species, development of socio-economic and psychological assessments on the drivers behind human-eagle conflicts, and the strengthening of technical capacities of rural communities, such as appropriate poultry management.
The Black-and-chestnut Eagle Spizaetus isidori is an endangered and little-known top predator of South American montane forests. To better understand the breeding ecology and threats of this eagle, we studied several pairs between 2017 and 2022 in the central Andes of Peru. We recorded 62 adults, one immature, and 36 juveniles in 36 territories. These territories were in mountainous areas (altitudinal range 690–3,810 m a.s.l.), widely covered by montane forests (43.8–99.7% cover), and secondarily by open land (0.3–56.2% cover), far from urban settlements (1.3–27.1 km). Nesting sites (N = 15) were at medium altitudes (1,330–2,330 m a.s.l.) in steep hillsides or ravines (15–55°), having no preferential cardinal orientation, and relatively close to permanent water courses (20–800 m), open areas (30–930 m) and sites with human activity (120–2,200 m). Nests (N = 15) were placed at the top of tall (28–40 m) and thick-stemmed (DBH range 0.53–1.52 m) emergent trees of nine genera, with Ficus and Juglans being the most used. Incubation and brood-rearing occurred during the dry season (Mar–Nov). The wooded slopes where the eagles nested are being replaced by crops and livestock pastures, causing an estimated loss of 218.2 km2 of forest cover in our study area (5,056 km2) during the last 20 years. We detected human persecution in 55.5% of the territories, resulting in 26 juveniles, four adults, two immatures, and nine unaged eagles killed. Preventing the local extinctions of these eagles will require long-term population monitoring, improving knowledge of its ecology, mitigation of human-eagle conflict, development of education programs, and strengthening of land use inspection.
El halcón selvático de collar (Micrastur semitorquatus) es el miembro más grande de su
género. Se encuentra en una amplia variedad de hábitats desde el centro de México
hasta el sur de Brasil. En el año 2021 se localizó un nido de M. semitorquatus dentro
de una de las estructuras que conforman el complejo arqueológico de Xkipché, en el
estado de Campeche, México, lo que sería el primer registro en esta región. El mismo
se encontraba a nivel del suelo y en su interior se observaron restos de una iguana
negra (Ctenosaura similis), plumas de la chara yucateca (Cyanocorax yucatanicus) y del
momoto cejas azules (Eumomota superciliosa). Se cree que la anidación de esta especie
en construcciones humanas es un comportamiento adaptativo debido a la pérdida de
hábitat, aunque también puede ser por la flexibilidad de la especie. La información
aquí presentada da pauta para futuros estudios en la zona, teniendo en cuenta que
la fragmentación y la pérdida de hábitat a causa de la actividad de las personas, que
condicionan la supervivencia de esta y otras especies.
Several rare species of the island of Cuba are facing local extinction risk and threats. The endemic Cuban Black-Hawk (Buteogallus gundlachii) is threatened by habitat loss as ~50% of its original habitat has been fragmented by tourism activity. Despite this situation, little information on its population size is available and its abundance patterns in relation to environmental variables are largely unknown. Such information is urgently needed to understand its geographic distribution and population abundance trends. We modeled the spatial patterns of abundance of the hawk in central Cuba and then assessed the effectiveness of protected areas for conserving this species. We fitted an ecological niche model to occurrence data of the Cuban Black-Hawk. The centroid of the predicted distribution range was calculated in ecological space and the multidimensional Euclidean distance to the niche centroid (DNC) was estimated. A function describing the relationship between the species abundance and the distance to the niche centroid was used to construct a map depicting the distribution of the Cuban Black-Hawk abundance. The potential distribution range of the raptor encompasses a 703.4 km² area and represents 12.5% of the total study area. Results show an inverse relationship between DNC and abundance (R² = 0.37): the sites closer to the centroid of the ecological niche of the species contain more individuals. The model shows that a shorter distance to the coastline and larger distance to urban zones increase the probability of occurrence of the hawk. Based on these results, we estimated that only 24% of the area where a high hawk abundance is expected is currently included in protected areas. We suggest establishing priority survey sites and strengthening protection of the Cuban Black-Hawk in the zones we identified as most valuable in the archipelago. This approach could also be used for other rare and endemic species in other ecosystems.
Abstract In birds, obtaining information related to nest occupancy, offspring status or breeding success is essential for population monitoring, particularly for species of conservation concern. Traditionally, nest monitoring demands a lot of time and effort in order to gather accurate information and avoiding nest disturbance. Instead, Unmanned Aerial Vehicles (UAVs, hereafter drones) present an alternative to traditional methods, but few studies have been done measuring their influence on birds’ behavior and reproductive success. We addressed the utility of drones equipped with an on‐board camera in examining nesting status of the endangered Chaco Eagle Buteogallus coronatus in semiarid environments of central Argentina, as well as the degree of disturbance of drone flights to individuals. We performed 76 drone flights at 41 Chaco Eagle nests registering flight duration, tree height, nest relative height and pilot proximity to nest. Of those, 38 flights were done over occupied nests where we recorded adult behavior. Before drone took off, most adult eagles remained in the nests or in the surroundings (
Diurnal birds of prey are the predominant apex avian predators for most terrestrial ecosystems. Besides the role they play as top predators on food webs, raptors are also among the most susceptible species to the negative effects of habitat transformations and human perturbations, in part due to their large habitat requirements, low population densities, and turnover rates. All these features make birds of prey especially susceptible to the variety of human pressures on their populations and habitats. As a result, a great number of the recognized raptor species are currently listed as threatened. In the Neotropical realm, which extends from tropical Mexico to South America, one of the rarest, most elusive and severely threatened birds of prey is the Chaco Eagle (Buteogallus coronatus). Here we examine and review information on the biology of Chaco Eagle, highlighting the most important threats to this species in the arid and semiarid landscapes of Argentina. We also examine management and conservation actions undertaken as a result of long-term studies on the ecology of the species, as well as gaps and future research needs with the aim of preserving Chaco eagle populations in natural environments.
Understanding species-environment relationships is key to defining the spatial structure of species distributions and develop effective conservation plans. However, for many species, this baseline information does not exist. With reliable presence data, spatial models that predict geographic ranges and identify environmental processes regulating distribution are a cost-effective and rapid method to achieve this. Yet these spatial models are lacking for many rare and threatened species, particularly in tropical regions. The harpy eagle (Harpia harpyja) is a Neotropical forest raptor of conservation concern with a continental distribution across lowland tropical forests in Central and South America. Currently, the harpy eagle faces threats from habitat loss and persecution and is categorized as Near-Threatened by the International Union for the Conservation of Nature (IUCN). Within a point process modeling (PPM) framework , we use presence-only occurrences with climatic and topographical predictors to estimate current and past distributions and define environmental requirements using Ecological Niche Factor Analysis. The current PPM prediction had high calibration accuracy (Continuous Boyce Index = 0.838) and was robust to null expectations (pROC ratio = 1.407). Three predictors contributed 96% to the PPM prediction, with Climatic Moisture Index the most important (72.1%), followed by minimum temperature of the warmest month (15.6%) and Terrain Roughness Index (8.3%). Assessing distribution in environmental space confirmed the same predictors explaining distribution , along with precipitation in the wettest month. Our reclassified binary model estimated a current range size 11% smaller than the current IUCN range polygon. Paleoclimatic projections combined with the current model predicted stable climatic refugia in the central Amazon, Guyana, eastern Colombia, and Panama. We propose a data-driven geographic range to complement the current IUCN range estimate and that despite its continental distribution, this tropical forest raptor is highly specialized to specific environmental requirements.
El zopilote aura (Cathartes aura) es una de las aves carroñeras más abundantes del continente americano, sin embargo, algunos detalles de su biología reproductiva son totalmente desconocidos en varios países. En febrero de 2018 encontramos un nido con dos huevos en una cavidad rocosa natural en el departamento de Usulután, El Salvador. A partir de esa fecha monitoreamos y documentamos el desarrollo y algunos aspectos conductuales de los polluelos. Los huevos eclosionaron en marzo, y en abril ya había crecimiento de plumas secundarias. Con aproximadamente 36 días de edad, uno de los polluelos desapareció por posible depredación. En mayo, el polluelo restante presentó inicio de crecimiento de plumas en las alas, en la parte dorsal y frontal del cuerpo. Para finales de mayo, el plumaje juvenil era casi completo, y finalmente en junio, el juvenil fue visto fuera de la cavidad alimentándose con otros individuos de C. aura. Esta especie está catalogada como residente en el país, sin embargo hasta la fecha no se habían encontrado nidos ni se conocían detalles del desarrollo de los polluelos.
High mortality by electrocution has been suggested to be the main factor behind the reduction of several birds of prey populations across the world. Almost nothing is known, however, about the impact of power lines on this group of birds in the Neotropical Region. Here we estimate electrocution rates for birds on power lines covering both arid and semiarid biomes of central Argentina. We conducted six bi-monthly power line and raptor surveys throughout 355 km of lines and roads covering an area of approximately 12,000 km ² . We described the structural design of 3,118 surveyed electricity pylons. We found 34 electrocuted individuals of four bird families that constitute an annual bird electrocution rate of 0.011 bird/pylon/year. Bird electrocution occurred mostly on concrete pylons with jumpers above the cross-arm. Larger birds of prey had a higher electrocution rate than smaller species. The Crowned Solitary Eagle Buteogallus coronatus was disproportionately affected by this mortality source when compared with its low population density. Electrocution incidents occurred mostly in a few electric pylon designs that represent only 10.2 % of the power pylons monitored in the study area. Therefore, the change or modification of a small fraction of pylons would almost eliminate bird electrocution incidents in our study area. Our results prove that electrocution is a relevant cause of mortality for Crowned Solitary Eagles and urgent mitigating actions are needed to reduce this mortality factor.
Human-wildlife conflicts currently represent one of the main conservation problems for wildlife species around the world. Vultures have serious conservation concerns, many of which are related to people's adverse perception about them due to the belief that they prey on livestock. Our aim was to assess local perception and the factors influencing people's perception of the largest scavenging bird in South America, the Andean condor. For this, we interviewed 112 people from Valle Fértil, San Juan province, a rural area of central west Argentina. Overall, people in the area mostly have an elementary education, and their most important activity is livestock rearing. The results showed that, in general, most people perceive the Andean condor as an injurious species and, in fact, some people recognize that they still kill condors. We identified two major factors that affect this perception, the education level of villagers and their relationship with livestock ranching. Our study suggests that conservation of condors and other similar scavengers depends on education programs designed to change the negative perception people have about them. Such programs should be particularly focused on ranchers since they are the ones who have the worst perception of these scavengers. We suggest that highlighting the central ecological role of scavengers and recovering their cultural value would be fundamental to reverse their persecution and their negative perception by people.
The Black-and-chestnut Eagle (Spizaetus isidori), is one of the least known Neotropical
raptors, with scarce information about its basic ecology throughout its entire distribution
range. Internationally it is categorized as Endangered. On February 17th 2014, the first
nest recorded for the species in Argentina, was found in Jujuy Province. The nest is
located within the UNESCO Biosphere Reserve of Las Yungas, very close to human
settlements. The pair successfully bred during the austral winter and spring in 2014
and produced one fledgling. Its diet included exclusively birds, being guans (Penelope
sp. possibly P. obscura and P. dabbenei) the most common prey followed by birds of
prey and domestic fowl (Gallus gallus). The diet of this pair suggests that this eagle
could play a relevant role as a super-predator in the study area by impacting the most
relevant frugivorous species as well as other top predators. The presence of domestic
fowl in the diet is especially worrisome as it suggests the existence of a real conflict
between eagles and local settlers. Further work is needed to clarify whether the results
from this nest are representative of other areas of the species distribution in Argentina.
Data about death incidents of Harpy Eagles in Ecuador were documented as a result of prolonged monitoring of their breeding activity. Adult mortality was recorded less frequently than juvenile mortality (9.4% and 28.6% respectively) and all adults were killed due to human persecution (shots) for different reasons. Reasons for juvenile death included falling or loss of height from the canopy while learning to fly and becoming trapped near the ground. There was one case where a juvenile was shot, and another of death after some aggressive behavior of an adult toward the juvenile when it should have been beginning its dispersion. This is the first account on mortality causes in a natural population of Harpy Eagle.
Large birds of prey, such as the Black-and-chestnut Eagle (Spizaetus isidori), are among the most threatened species, due to their high habitat requirements as top predators. In order to develop effective conservation plans for this group, more detailed knowledge of the different aspects of their biology and interaction with human communities is required. We evaluated the nestling diet of the Black-and-chestnut Eagle for three breeding periods using three different methods in the rural area of Gachalá-Cundinamarca, on the eastern slope of the Eastern Cordillera of Colombia. In addition, we surveyed people living in the study area to assess the existence of potential eaglehuman conflicts. Of the eight taxa recorded as prey, the Andean Guan (Penelope montagnii) was the most frequent (40%), while the House Chicken (Gallus gallus) contributed the greatest biomass (47%). Our surveys reveal an estimated yearly loss of one to two domestic fowl individuals per household, with 57% of owners surveyed claimed to have suffered losses. According to the survey results, inhabitants would prefer not to have the eagle breeding close to their houses (< 10 km), and would consider killing eagles if they preyed upon more than five domestic fowl individuals a year. To reduce the threat and the current human-eagle conflict in the area, it is important to consider "win-win" strategies, some of which are already being studied in the area, such as birdwatching initiatives.
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.
RESUMEN.-Sobre la base de una compilación de publicaciones recientes (2005−2015) e investigaciones en curso sobre aves rapaces asociadas al bosque templado austral (BTA) en el sur de Argentina, identificamos 40 líneas te-máticas que en conjunto involucran al menos a 35 investigadores. La mayor parte de los proyectos en marcha están enfocados hacia las aves rapaces diurnas y casi todos están en desarrollo en hábitats fuera del bosque propiamente tal. Sólo un estudio sobre la lechuza bataraz (Strix rufipes) fue realizado en el bosque pleno. De las 104 publicaciones generadas en la última década sobre aves rapaces asociadas al BTA, la mayor parte documenta resultados obtenidos fuera del bosque pleno. Hasta la fecha, tres especies siguen siendo muy poco conocidas: peuquito (Accipiter chi-lensis), matamico blanco (Phalcoboenus albogularis) y aguilucho cola rojiza (Buteo ventralis). En los dos primeros casos, ninguna publicación formal fue generada en la última década, y en el caso del aguilucho cola rojiza sólo una recopilación de avistajes fue documentada. Esto se explica por la dominancia espacial de ecosistemas abiertos en Argentina, lo cual a la vez implica una logística de investigación más sencilla que la necesaria en bosques. No regis-tramos estudios en curso de carácter conjunto entre investigadores argentinos y chilenos, excepto por una publica-ción binacional. Considerando las publicaciones históricas, el aguilucho andino (Buteo albigula) es la única especie del BTA que ha sido estudiada en Argentina y Chile. Las demás especies son poco conocidas en ambos países. Esto justifica la realización de estudios en conjunto o coordinados entre estos dos países para comprender mejor los as-pectos ecológicos y desarrollar estrategias de conservación más efectiva. La predominancia de bosques de transición ecotonal en el sur de Argentina puede ser clave en el manejo y conservación de las aves rapaces de bosque ya que al superponerse los elementos de la estepa, el bosque y la cordillera, proporcionaría una fuente rica en recursos trófi-cos. PALABRAS CLAVE.-Argentina, aves rapaces, bosque templado austral, bosques de transición, cooperación binacional, ecotono, estepa. ABSTRACT.-Based on recently published works (2005−2015) and on current research conducted in central and/ or southern Argentina involving raptor species inhabiting the austral temperate forest, we identified 40 different research lines conducted by at least 35 researchers. Most ongoing projects focus on diurnal raptors, and almost all take place in arid areas or at the forest-steppe ecotone. Only one recent study, which focused on Rufous-legged Owl (Strix rufipes), was conducted in forests. Most papers on raptor species dwelling in the austral temperate forests that were published during last decade (N = 104) in Argentina document results obtained outside forests. To date, three species in particular have been little studied: the Chilean Hawk (Accipiter chilensis), the White-throated Caracara (Phalco-boenus albogularis), and the Rufous-tailed Hawk (Buteo ventralis). In the last decade, the two first species have not received formal publications, and only a compilation of sighting records of the Rufous-tailed Hawk was published. These patterns are explained by a dominance of open environments in Argentina, where logistics are much simpler than those required for fieldwork in forest areas. Studies involving Argentinean and Chilean researchers are not being conducted at the present, and only one recent publication is bi-national. Considering historical publications, it can be said that the White-throated Hawk (Buteo albigula) is the only forest species that has been studied in both Argentina and Chile. All other forest raptors associated with the BTA are little known in both countries. This justifies Boletín Chileno de Ornitología 21 (1-2): 15-28 Unión de Ornitólogos de Chile 2015 EDICIÓN ESPECIAL: AVES RAPACES DEL BOSQUE TEMPLADO AUSTRAL
Eradication is often the preferred method of invasive species management on islands; however, its consequences may affect native communities. Feral goats (Capra hircus), donkeys (Equus asinus), and pigs (Sus scrofa) were eradicated from Santiago Island in the Galapagos Archipelago by 2005. Because feral goats were the dominant herbivores on Santiago Island until their eradication, we examined the consequences of goat eradication on the diet of territorial Galapagos Hawks (Buteo galapagoensis) through a comparative study of observations of prey deliveries to nests before (1999–2000) and after (2010–2011) eradication. We predicted that vegetation recovery after eradication would limit the hawks’ hunting success of terrestrial prey and they would therefore switch to predominantly arboreal prey. We did not observe the predicted switch from terrestrial to arboreal prey in the diet; on the contrary, after goat eradication, hawks delivered significantly fewer arboreal prey items. However, introduced black rats (Rattus rattus) represented a significantly greater proportion of the hawks’ diet after eradication, particularly in moderate to dense vegetation (arid and transition habitats), replacing other prey items. Overall, 73% of total prey biomass delivered after eradication consisted of introduced rats, compared to only 20% before eradication. This study documents the complex interaction of predators and introduced prey, even in relatively simple ecosystems.
We conducted surveys for the endangered Ridgway's Hawk, Buteo ridgwayi, in Los Haitises National Park, Dominican Republic, and in areas outside the park during the breeding seasons 2002 and 2003. In 2002, we recorded 47 individuals comprised by 19 territorial pairs and 8 single hawks. Of the former, 9 pairs attempted nesting and 2 pairs were successful in fledging 3 young. In 2003, we recorded 93 individuals composed of 37 territorial pairs, 9 single hawks, and 10 fledglings. Of 37 pairs, 30 attempted nesting and 8 pairs were successful in fledging 10 young. Of the 28 nests, 32% (9/28) were built on top of Palmchat, Dulus dominicus, and on living trees, having a nest success of 25%. Outside Los Haitises region, 2 hawks were observed on the Samaná Peninsula. During 2002, no hawks were observed in the Sierra Bahoruco National Park and outlying areas in southwestern and central Dominican Republic.
Los pingüinos son aves marinas del hemisferio sur. Son atléticos, sorprendentes y antiguos. Algunos de ellos pueden surcar increíbles distancias, como el pingüino de Magallanes, que migra más de 4.000 kilómetros desde Tierra del Fuego, en Argentina, hasta Río de Janeiro, Brasil. Los pingüinos de esta especie pueden nadar más de 170 kilómetros en un día, y lo realizan con su propia energía… ¡sin necesidad de usar combustibles fósiles! Un adulto reproductor es capaz de nadar unos 16.000 kilómetros al año, la distancia promedio que recorre un automóvil en el mismo lapso de tiempo. Los pingüinos emperadores reproducen en la Antártida, donde mantienen sus huevos calientes sosteniéndolos sobre sus patas, mientras soportan temperaturas tan extremas como −30o C a −40oC, y gélidos vientos que alcanzan los 144 Kilómetros por hora. Los humanos no podrían sobrevivir mucho tiempo en esas condiciones. Si esto no le sorprende, imagínese ayunar en esas condiciones durante cuatro meses, como lo hace un macho emperador, sin un bocado para comer excepto hielo y nieve.
Sin dudas, los pingüinos son criaturas extraordinarias. Si bien en líneas generales se asemejan entre sí, pueden variar en tamaño: desde el pequeño pingüino azul, de apenas un kilogramo de peso y buceo superficial, hasta el pingüino emperador, que alcanza los 40 kilogramos y puede bucear hasta 500 metros, manteniendo su respiración por 23 minutos. En comparación, el récord de buceo para un humano es de 101 metros y 4,13 minutos. Los pingüinos viven en diversos ambientes, desde las tropicales islas Galápagos hasta la gélida Antártida, y a lo largo de islas y continentes del hemisferio sur. La mayor parte de las especies son de color blanco y negro, algunas ostentan crestas amarillas y anaranjadas o poseen coloración azulada. En condiciones naturales, algunos individuos viven más de 30 años. Nidifican en desiertos, bosques, roca desnuda, cuevas, bajo arbustos, bajo árboles y en espacios abiertos.
El registro fósil más antiguo de estas aves es de unos 55 millones de años, y las evidencias paleontológicas sugieren que se diversificaron entre 10 y 40 millones de años atrás. Sus orígenes, sin embargo, se remontan al período Cretácico, entre 140 a 65 millones de años atrás, cuando su ancestro era un ave marina voladora, probablemente un macá, un albatros o un ave fragata. En este libro, organizamos los capítulos basados en las relaciones entre las distintas especies según su morfología actual y filogenia molecular. Los seis géneros de pingüinos vivientes (Aptenodytes, Eudyptes, Eudyptula, Megadyptes, Pygoscelis y Spheniscus) se encuentran claramente definidos, y su clasificación ha resistido la prueba del tiempo. Sin embargo, las relaciones entre especies dentro y fuera de su género no son tan fijas.
Comenzamos el libro con los pingüinos más grandes, el rey y el emperador (Aptenodytes), y lo culminamos con el más pequeño, el pingüino azul (Eudyptula). Para cada especie, se proveen los nombres comunes y el científico, descripción, estatus taxonómico, rango y distribución, resumen de tendencias poblacionales, estatus según la Unión Internacional para la Conservación de la Naturaleza (UICN), historia natural, tamaños y tendencias poblacionales, mapa y tamaño de colonias, ciclo anual general, principales amenazas, acciones de investigación y conservación recomendadas, y esfuerzos de conservación en marcha. Mantenemos el mismo orden en cada capítulo. El material presentado informa al lector sobre las acciones humanas, ya sea de investigación, políticas, o de conservación en el terreno. Esperamos que este libro haga más que meramente informar acerca de los pingüinos. Primero debemos conocer, para luego entender, y finalmente poder actuar. Confiamos en que leerlo lo motivará a ayudar a los pingüinos.
Aunque muchos pingüinos viven en áreas remotas, los humanos tienen un gran impacto sobre ellos. Los primeros exploradores antárticos dependieron de estas aves para alimentarse, varios miles fueron capturados por su aceite, y los primeros colonizadores en general consumieron tanto adultos, como huevos y pichones. Actualmente, los pingüinos se encuentran entre las aves marinas más amenazadas. Alrededor de dos tercios de las especies de pingüinos están incluidas en la Lista Roja de la UICN de Especies Amenazadas. Las capturas por humanos han disminuido, pero el cambio climático, la pesca, la degradación del hábitat, las enfermedades, e incluso el turismo, se ciernen como amenazas vigentes. Los impactos humanos sobre las aves marinas probablemente continuarán a medida que la población humana aumenta superando los 7 mil millones de personas y con ello, el consumo. El destino de las aves marinas, desde los albatros a los pingüinos, está, sin dudas, vinculado al nuestro.
Los pingüinos se encuentran entre las especies de aves más populares y amadas. La marcha de los pingüinos, la documental más taquillera de todos los tiempos, se basa en la vida de los pingüinos emperadores. Si se presta atención a los libros para niños o a las películas, los pingüinos ocupan un lugar importante en la cultura humana. Este libro describe las vidas de todas las especies de pingüinos del mundo, gracias al aporte de 49 investigadores procedentes de 12 países en 5 continentes. Este es el primer libro que reúne a los principales expertos del mundo para compartir sus conocimientos sobre cada una de las especies.
Esta obra es un ícono para la Global Penguin Society (GPS), un grupo dedicado al bienestar de los pingüinos. Mitigar y manejar las amenazas para los pingüinos a escala local, regional y global, requiere de financiamiento y de la construcción de una red social involucrada en tales objetivos. Global Penguin Society ayuda a los investigadores, gobiernos y propietarios de tierras privadas a ser la voz de los pingüinos.
Los pingüinos son centinelas ambientales, y si bien la gente los ama, pocas personas están totalmente conscientes de su declinación. Por su carisma natural, ellos son los perfectos embajadores para clamar por la salud de nuestros océanos y sus costas.
The Crowned Eagle (Buteogallus coronatus) is a large Neotropical raptor and one of the most threatened raptor species in the world, with a maximum estimated population of 1500 individuals. The main threats identified for the species are habitat loss and degradation and non-natural mortality by direct persecution and collisions with human infrastructures. Here we report cases of direct persecution on the species in Argentina. We compiled all the available published information, as well as cases of birds delivered to the rehabilitation center of the Program of Conservation and Rescue of Birds of Prey of the Buenos Aires Zoo. For the period 1980 to 2014, we found 83 cases from almost every Argentine province where the eagle is present. Our results show that direct persecution is probably an important cause of mortality for the eagles in the Argentinean territory.
Road mortality is the leading source of biodiversity loss in the world, especially due to fragmentation of natural habitats and loss of wildlife. The survey of the main species victims of roadkill is of fundamental importance for the better understanding of the problem, being necessary, for this, the correct species identification. The aim of this study was to verify if DNA barcodes can be applied to identify road-killed samples that often cannot be determined morphologically. For this purpose, 222 vertebrate samples were collected in a stretch of the BR-101 highway that crosses two Discovery Coast Atlantic Forest Natural Reserves, the Sooretama Biological Reserve and the Vale Natural Reserve, in Espírito Santo, Brazil. The mitochondrial COI gene was amplified, sequenced and confronted with the BOLD database. It was possible to identify 62.16% of samples, totaling 62 different species, including Pyrrhura cruentata, Chaetomys subspinosus, Puma yagouaroundi and Leopardus wiedii considered Vulnerable in the National Official List of Species of Endangered Wildlife. The most commonly identified animals were a bat (Molossus molossus), an opossum (Didelphis aurita) and a frog (Trachycephalus mesophaeus) species. Only one reptile was identified using the technique, probably due to lack of reference sequences in BOLD. These data may contribute to a better understanding of the impact of roads on species biodiversity loss and to introduce the DNA barcode technique to road ecology scenarios.
Prey consumed by the Crowned Eagle (Harpyhaliaetus coronatus) in the southern limits of its range in Argentina. INTRODUCCIÓN El Aguila Coronada (Harpyhaliaetus coronatus) se distribuye en el sur de Sudamérica desde Bolivia y Brasil a través de Paraguay, Uruguay y Argentina (Collar et al. 1992), pero a pesar de su amplia distribución y gran tamaño es rara y difícil de observar (Narosky & Yzurieta 1987). En la Argentina es una especie prote-gida desde el año 1954 y ha sido categorizada como vulnerable (Fraga 1997). Aunque se han aportado nuevos registros de la especie en el límite sur de su rango de distribución (Delhey 1992, de Lucca 1993, tinúan siendo desconocidos. La especie es considerada un ave que caza principalmente al amanecer y en el crepúsculo, relativa-mente mansa y renuente a volar ante la aproximación de personas (Bellocq et al. 1998), y que habita bosques y estepas arbusti-vas xerófilas (Collar et al. 1992). Datos anecdóticos indican el consumo de varios vertebrados, incluyendo aves (Tinamidae), mamíferos tales como armadillos (Dasypodi-dae), zorrinos (Mustelidae) y comadrejas (Didelphidae), reptiles y carroña (Giai 1950, Collar et al. 1992). Unicamente Alvarez (1933) analizó el contenido estomacal de un individuo en Uruguay y reportó restos de cor-dero (Ovis aries) y aves de corral (Gallus domesti-cus). El objetivo de esta nota es brindar información acerca de los hábitos alimenti-cios del Aguila Coronada en el límite austral de su distribución y dar a conocer nuevos registros de la especie para el área central de Argentina.
The raptor populations of a succession of seven habitats, from the primary undisturbed forest to the derived pastures or plantations in southern Ivory Coast, is described. A comparative survey, considering only four main habitats, was made in Guiana and southern Mexico. Similar patterns of species distribution are found on the two continents: 1. Between 36 and 42 percent of the species reach their greatest densities in the primary forest and decrease rapidly as soon as the forest begins to be cleared. 2. Some primary forest species (18-21%) are more tolerant and rarely decrease, so long as areas of secondary forest remain. 3. Two or three species (8-14%) are more abundant in the intermediate stages of the succession than in either extremity. 4. An equal number of species, appearing early in the succession but absent from the primary forest, survive as long as large trees are available. 5. Between 14 and 25 percent of the whole set of species are savannah birds, occurring only in large clearings and now spreading into the forest belt. To preserve the true forest species, undisturbed areas of primary forest have to be spared during lumbering operations, clearings have to be small, separated by patches of forest and dotted with large trees. Human hunting of medium-sized animals must be limited if eagles are to be saved.
The Atlantic Forest of northeast Brazil hosts a unique biota which is among the most threatened in the Neotropics. Near-total conversion of forest habitat to sugar cane monocultures has left the region's endemic forest-dependent avifauna marooned in a few highly-fragmented and degraded forest remnants. Here we summarise the current status of 16 globally threatened species based on surveys conducted over the last 11 years. We found a bleak situation for most of these species and consider that three endemics: Glaucidium mooreorum (Pernambuco Pygmy-owl), Cichlocolaptes mazarbarnetti (Cryptic Treehunter) and Philydor novaesi (Alagoas Foliage-gleaner) are most likely globally extinct. Some positive news can, however, be reported for both Leptodon forbesi (White-collared Kite) and Synallaxis infuscata (Pinto's Spinetail) which may warrant re-evaluation of their respective red list statuses. We outline a road map to prioritise conservation interventions in the region directed at preventing the extinction of this suite of threatened bird species and their companion biota.
In Argentina, deforestation due to agriculture expan-sion is threatening the Semi-arid Chaco, one of the largest forested biomes of South America. This study focuses on the north-west boundary of the Argentine Semi-arid Chaco, where soybean is the most important crop. Deforestation was estimated for areas with dif-ferent levels of soil and rainfall limitation for agricul-ture between 1972 and 2001, with a finer analysis in three periods starting in 1984, which are characterized by differences in rainfall, soybean price, production cost, technology-driven yield and national gross domestic product. Between 1972 and 2001, 588 900 ha (c. 20% of the forests) were deforested. Deforestation has been accelerating, reaching >28 000 ha yr −1 after 1997. The initial deforestation was associated with black bean cultivation following an increase in rainfall during the 1970s. In the 1980s, high soybean prices stimulated fur-ther deforestation. Finally, the introduction of soybean transgenic cultivars in 1997 reduced plantation costs and stimulated a further increase in deforestation. The domestic economy had little association with defo-restation. Although deforestation was more intense in the moister (rainfall >600 mm yr −1) areas, more than 300 000 ha have already been deforested in the drier areas, suggesting that climatic limitations are being overcome by technological and genetic improvement. Furthermore, more than 300 000 ha of forest occur in sectors without major soil and rainfall limitations. If global trends of technology, soybean markets and climate continue, and no active conservation policies are applied, vast areas of the Chaco will be deforested in the coming decades.
Seventy-six percent (222) of the world's 292 species of diurnal raptors are found inainly or completely in the tropics. Forty-six percent of all tropical raptors are threatened by habitat loss, 11% by environmental contaminants, and 19% by direct persecution. Seventeen percent are threatened by two of these factors, 2% by all three factors. Regionally, 42% of all Neotropical, 60% of all Afrotropical, 60% of all Indomalayan, and 77% of all Australotropical raptors are threatened by one of more of these factors. IUCN classifies 27% of all tropical raptors (59 species) as Near Threatened, Vulnerable, Endan- gered, or Critically Endangered. Silnilar statistics are 23% (17 of 73 species), 14% (11 of 80 species), 33% (21 of 63), and 34% (12 of 35), for the Neotropical, Afrotropical, Indolnalayan, and Australotrop- ical regions, respectively. Thirty percent of all tropical raptors are endemics. Fifty-seven percent of all tropical raptors are complete, partial, or irruptive migrants. The degree of endemism and migration behavior varies among the four regions. Although some of the regional differences in conservation status reflect regional differences in knowledge, many appear to reflect ecological differences among the four regions.
Raptors have been reported to prey on livestock, causing considerable conflicts between birds of prey and local human communities. Previous studies have documented that human persecution is the most important threat to the endangered crowned eagle Harpyhaliaetus coronatus in central Argentina, due to a local belief that crowned eagles heavily and consistently prey on livestock. However, there are no empirical data supporting this assertion. Such information is crucial to evaluating possible measures to mitigate this human–wildlife conflict. We evaluated the feeding ecology of crowned eagles in semiarid habitats of central Argentina during the breeding seasons of 2002 to 2009. We also evaluated whether eagles are responsible for livestock predation and examined spatial-temporal variation in crowned eagles’ food habits. We identified 598 prey items consisting almost entirely of native prey: mammals (67.7%), reptiles (16.2%), birds (3.3%), fish (2.5%), and invertebrates (16.9%). We only recorded 1 (0.17%) occurrence of livestock prey remains, belonging to a domestic goat Capra hircus. Occurrences of the 4 main prey groups were not affected by habitat type or season. However, reptiles were recorded in higher numbers at sites where the diet of eagles was addressed by direct observation and video recording. Contrary to other human–predator conflicts worldwide, and assuming that the single livestock prey was not scavenged, our results show that crowned eagles rarely prey on livestock. We advocate reducing human–wildlife conflicts by implementing management and conservation measures and by educating local communities with respect to the ecological role of crowned eagles and other predators.
KEY WORDS: Crowned eagle · Harpyhaliaetus coronatus · Conservation · Persecution · Human–wildlife conflict · Feeding ecology · Central Argentina
La mortalidad anual de aves por causas antrópicas en los Estados Unidos se estima en 1 billón. Las aves rapaces urbanas son afectadas por varios de estos factores; sin embargo, se sabe muy poco sobre la frecuencia relativa y la magnitud de las causas entre individuos de una especie y entre especies. Revisé 86 publicaciones sobre causas de mortalidad y uso urbano por parte de aves rapaces de Estados Unidos y Canadá. En los Falconiformes (28 especies urbanas), para la mayoría de las especies se reportó mortalidad por colisión con vehículos y electrocución (73% y 48%, respectivamente), y los choques con vehículos o ventanas fueron la primera causa de mortalidad para el 39% y 12% de las especies, respectivamente. Para los Strigiformes (14 especies urbanas), las colisiones con vehículos (63%) y ventanas (47%) afectaron a la mayoría de las especies, y la principal causa de mortalidad fue por vehículos (32%) y electrocución (5%). Para el 45% de las rapaces urbanas se reportó mortalidad por choques con ventanas, los cuales representaron la principal causa de mortalidad para Accipiter striatus, A. cooperii, Falco columbarius y F. peregrinus. También se observó mortalidad por electrocuciones para un 45% de las especies. Las colisiones con vehículos afectaron a una gran proporción de las aves rapaces urbanas y no urbanas, tanto para especies que usan las autopistas para varias actividades (e.g., forrajeo), como para aquellas que no utilizan las autopistas. En general, la literatura sugiere que las colisiones y electrocuciones son fuentes importantes de mortalidad para la mayoría de las aves rapaces. Investigaciones futuras deberían determinar las consecuencias sobre la historia de vida y demografía de las poblaciones de rapaces.
The crowned eagle Harpyhaliaetus
coronatus is a large Neotropical eagle categorized as Endangered throughout its range. However, the threats to this species are poorly understood. We present data on the causes of death of crowned eagles in semi-arid forests of La Pampa province, central Argentina. Data was obtained from field surveys and from interviews with 62 local landowners during 1999–2004. Over this period five eagles were shot, one killed by a car, one was found dead in a cattle water trough, and one was found in captivity. From the interviews information was obtained about a further 10 cases of eagles being shot, disturbed or trapped. Five (13%) of 38 interviewed landowners who positively identified the species admitted having killed or disturbed eagles in the past but only two (5%) mentioned predation of eagles upon livestock as a problem. Persecution seems to be a significant threat to this species in central Argentina and future research and conservation action should be focused not only on gaining a better knowledge of the biology of the species but also on conservation and educational programmes involving local people.
Basado en un estudio muy extensivo de la literatura para 81 especies de Falconiformes(excluyendo Cathartidae) que se aparean principalmente en Centro y Sur América, hago un resumen de nuestro conocimiento más actual de la biologia y el estado de conservación en que se encuentran estas aves. La mayor parte de la información que se tiene sobre raptores diurnos de la región está basada en estudios que fueron llevados acabo en el sur de los Estados Unidos, el Petén en Guatemala, la parte noreste de América del Sur (Venezuela hasta las Guianas) y Chile. Las especies menos conocidos son residentes de bosque primario, especialmente de los géneros Accipiter, Leucoptemis y Micrastur. Falta describir nidos para 19 especies y menos de cinco nidos han sido descritos para 12 especies adicionales. No hay informacion sobre la alimentatión para seis especies y solamente información anecdotal ha sido publicada para 25 especies adicionales. Comportamiento de apareo se desconoce para 27 especies y solamente es conocido por anécdotas par 18 especies adicionales, Las costumbres migratorias de 28 especies se conocen muy poco. Información disponible permite juzgar razonablemente el estado de conservación para 39 especies y se puede estimarlo para 31 más, pero el juzgar de los 11 que restan seria solamente especulación.
Human disturbance can be a severe problem for some animal species. Behavioural ecology theory predicts that sensitivity to mortality risks, and thereby to disturbance, will be related to life-history characteristics. Long-lived species with low reproductive rates are expected to have a high cost of predation and therefore avoid risks strongly. In this paper we quantify the effect of roads on the Andean condor (Vultur gryphus) using behavioural indicators. We used a pair wise design, offering condors standardized food patches near and far from roads simultaneously. The patches consisted of dead adult sheep. We recorded condors' behaviour when visiting each patch. This study establishes the versatility of behavioural indicators and their usefulness to study conservation problems. We found that, although near and far patches were discovered after similar times and there were similar numbers of condors in the vicinity of near and far patches, the use of patches dif-fered strongly. In the patches far from roads many more condors came to feed, the average time spent per individual was longer, the proportion of time spent vigilant was lower, and the amount of food left uneaten on the carcasses was lower. These results strongly suggest that Andean condors clearly avoid roads, and behave in a way predicted from theory if they trade off safety for energy. This study shows that roads have stronger influence on the hab-itat use of Andean condors, than previously thought, and may be a significant problem for the species in populated areas.
Unlike resident bird species, the population sizes of migratory species can be influenced by conditions in more than one part of the world. Changes in the numbers of migrant birds, either long-term or year-to-year, may be caused by changes in conditions in the breeding or wintering areas or both. The strongest driver of numerical change is provided in whichever area the per capita effects of adverse factors on survival or fecundity are greatest. Examples are given of some species whose numbers have changed in association with conditions in breeding areas, and of others whose numbers have changed in association with conditions in wintering areas. In a few such species, the effects of potential limiting factors have been confirmed locally by experiment. In theory, population sizes might also be limited by severe competition at restricted stopover sites, where bird densities are often high and food supplies heavily depleted, but (with one striking exception) the evidence is as yet no more than suggestive. In some species, habitats occupied in wintering and migration areas, and their associated food supplies, can influence the body condition, migration dates and subsequent breeding success of migrants. Body reserves accumulated in spring by large waterfowl serve for migration and for subsequent breeding, and females with the largest reserves are most likely to produce young. Hence, the conditions experienced by individuals in winter in one region can affect their subsequent breeding success in another region. Such effects are apparent at the level of the individual and at the level of the population. Similarly, the numbers of young produced in one region could, through density-dependent processes, affect subsequent overall mortality in another region. Events in breeding, migration and wintering areas are thus interlinked in their effects on bird numbers. Although in the last 30–40 years the numbers of some tropical wintering birds have declined in western Europe and others in eastern North America, the causes seem to differ. In Europe, declines have mainly involved species that winter in the arid savannas of tropical Africa, which have suffered from the effects of drought and increasing desertification. In several species, annual fluctuations in numbers and adult survival rates were correlated with annual fluctuations in rainfall, and by implication in winter food supplies. In North America, by contrast, numerical declines have affected many species that breed and winter in forest, especially those eastern species favouring the forest interior. Declines have been attributed ultimately to human-induced changes in the breeding range, particularly forest fragmentation, which have led to increases in the densities of nest predators and parasitic cowbirds. These in turn are thought to have caused declines in the breeding success of some neotropical migrants, which is now too low to offset the usual adult mortality, but as yet convincing evidence is available for only a minority of species. The breeding rates and population changes of some migratory species have been influenced by natural changes in the availability of defoliating caterpillars. In other species, tropical deforestation is likely to have played the major role in population decline, and if recent rates of tropical deforestation continue, it is likely to affect an increasing range of migratory species in the future. Not all such species are likely to be affected adversely by deforestation, however, and some may benefit from the resulting habitat changes.
Swainson's hawks (Buteo swainsoni) were observed in the grasslands (pampas) of Argentina during the austral summer of 1995–96. Widespread agrochemical use to control insects had a profound effect on flocks of hawks foraging on grasshoppers and caterpillars throughout the pampas. We describe 19 mortality incidents and an estimated 5,095 dead hawks. Forensic analysis indicated that the organophosphate insecticide monocrotophos was responsible for the deaths at six separate sites, accounting for over 4,000 of the mortalities. Brain cholinesterase was lethally inhibited (>95%) and monocrotophos residues (n=31/45, mean=0.20 ppm, range 0.05–1.08 ppm) were found in the contents of the gastrointestinal tract. No other insecticide residues were found. Sample analyses, combined with interviews with farmers, indicated that monocrotophos was responsible for deaths at 17 of 19 mortality incidents.
Survival and recruitment estimates are important for predicting population viability and the efficacy of translocations. This information requires intensive monitoring postrelease, which is often economically or logistically infeasible. Since 2009, juveniles of the critically endangered Ridgway’s Hawk (Buteo ridgwayi) have been translocated from Los Haitises National Park to Punta Cana, Dominican Republic. Here, we use multistate capture–recapture models to estimate survival and recruitment of translocated Ridgway’s Hawks. We further examine whether survival or recruitment differed between sexes or translocation status (translocated vs. wild-reared birds in Los Haitises). Survival was relatively high for breeders, nonbreeders, and juveniles, and did not differ by translocation status or sex. Translocated juveniles were recruited into the breeding population at Punta Cana at more than double the rate of wild-reared juveniles in Los Haitises—likely because more unoccupied territories were available in Punta Cana. Our results show that translocation does not reduce survival, but does increase recruitment, of Ridgway’s Hawks when territories are available in suitable habitat. Future work should evaluate the reproductive performance of Ridgway’s Hawks in Punta Cana and determine the effects of translocations on the population in Los Haitises. Although the types of data collected during postrelease monitoring are often determined by funding, feasibility, and research objectives, our results demonstrate the importance of continued monitoring of translocated animals.
Certain birds enable people to comprehend the inexplicable because they embody contrasts and resolve oppositions, and some birds have particular attributes that make them especially adept at expressing these symbolic meanings. This analysis focuses on two bird families that are central to the social organization of many societies in the Americas for their relationship to both life and death, and considers how these birds are able to mediate cultural oppositions expressed through the myths, rituals, art, and architecture portrayed in both ancient and contemporary cultures. Having features associated with both life and death, hummingbirds and vultures embody a duality that enables them to fly symbolically higher into the heavens and lower into the underworld than many other birds. Ethnographic examples from Mexico, Costa Rica, and Peru are used to illustrate the ways these particular birds are seen as transforming life and death by leading to a more profound understanding of reality as an ongoing cycle of rebirth and renewal.
Reports on a nine-year project in lowland tropical moist forest at Tikal, Guatemala, studying nearly the entire raptor community, sponsored by The Peregrine Fund, Boise, Idaho.
Ospreys (Pandion haliaetus) winter throughout the country of Colombia. Recoveries of banded Ospreys indicate that many are shot in the country with the number increasing since the 1970s. The increased incidence of shooting has coincided with the development of aquaculture facilities in Colombia that raise tilapia (Oreochromis spp.). Because these facilities typically lose production to birds such as Ospreys that depredate fish, we conducted a survey of 83 facilities in three states or departments in Colombia in 2001 to determine the species of birds that take fish at aquaculture facilities and the numbers that are killed each year. Our results showed that bird depredation occurs at aquaculture facilities throughout the country, but mostly in the southern portion of the country in the department of Huila. Facility managers reported shooting Ospreys in all three departments with as few as five individuals shot annually in Antioquia in northern Colombia to as many as 270 shot annually in Huila. In addition, facility managers reported shooting nine other species of birds including Green Kingfishers (Chloroceryle americana), Great Kiskadees (Pitangus sulphuratus), Snowy Egrets (Egretta thula), Great Egrets (Casmerodius albus), Olivaceous Cormorants (Phalacrocorax olivaceus), Black-crowned Night-Herons (Nycticorax nycticorax), White-necked Herons (Ardea cocoi), Cattle Egrets (Bubulcus ibis), and Striated Herons (Butorides striatus), for a total estimate of >9000 birds shot in the three departments annually. A number of alternative methods to shooting had been used to reduce losses to birds including the installation of netting, overhead wires, scarecrows, and noise making devices, but, neither these methods nor shooting, were effective in deterring avian predators.
Lead is a prominent and highly toxic contaminant with important impacts to wildlife. To understand the degree to which wildlife populations are chronically exposed, we quantified lead levels within American black vultures (Coragyps atratus; BLVU) and turkey vultures (Cathartes aura; TUVU), two species that are useful as environmental sentinels in eastern North America. Every individual sampled (n=108) had bone lead levels indicative of chronic exposure to anthropogenic lead (BLVU: x¯=36.99±55.21mg Pb/kg tissue (±SD); TUVU: x¯=23.02±18.77mg/kg). Only a few showed evidence of recent lead exposure (BLVU liver: x¯=0.78±0.93mg/kg; TUVU liver: x¯=0.55±0.34mg/kg). Isotopic ratios suggested multiple potential sources of lead including ammunition, gasoline, coal-fired power plants, and zinc smelting. Black and turkey vultures range across eastern North America, from Quebec to Florida and individuals may traverse thousands of kilometers annually. The extent to which vultures are exposed suggests that anthropogenic lead permeates eastern North American ecosystems to a previously unrecognized degree. Discovery of an epidemic of chronic lead exposure in such widespread and common species and the failure of soft-tissue sampling to diagnose this pattern has dramatic implications for understanding modern wildlife and human health concerns.
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Ridgway's Hawk (Buteo ridgwayi) is endemic to Hispaniola and its satellites, where it occurs in a wide variety of habitats. We studied this hawk in the wet limestone karst forest of the Dominican Republic between January and June 1976. The hawk is sexually dimorphic with females somewhat larger than males. Display flights of territorial pairs began in January and were observed most often between 10:00 and 12:00. Mean home range for three pairs was 57.8 ha. Nest building was first observed on 25 February. Construction was concentrated in the morning and males did most of the building. Incubation (two eggs) was underway at one nest on 22 March. Females performed all of the incubation except when males took over after food exchanges. Hatching at one nest occurred on 19 and 20 April. At another nest two chicks fledged during the 12th week after egglaying. Both sexes defended nests against intra- and interspecific intruders. Males captured 91% of prey brought to the nests. Lizards and snakes were the most numerous prey brought to nests while mammals formed the bulk of prey biomass. Birds were also brought to young. Ridgway's Hawks used four hunting techniques: (1) Still Hunting, (2) Hang-Searching (slow gliding flight), (3) Foot-Thrusting (thrusting foot into vegetation and cavities to flush prey), and (4) Direct Stoop from soaring. The hawk has three basic vocalizations: (1) Kleeah, used in self-assertive and aggressive contexts; (2) Weeup, given in food exchanges and displays, and (3) the Whistle-Squeal, given during high-intensity interactions. Our observations suggest that B. ridgwayi is closely related to B. lineatus.
West Indian ecosystems have undergone extensive changes since the arrival of Europeans almost 500 years ago. Massive deforestation, introduced predators and competitors, and shooting are major reasons for declines in West Indian bird populations. Several raptor species are of particular concern, including the Cuban and Grenadan populations of the Hook-billed Kite (Chondrohierax uncinatus), Snail Kite CRostrhamus sociabilis), the Cubali^ Hispaniolan, and Puerto Rican races of the Sharp-shinned Hawk (Accipiter striatus), Gundlach's Hawk (A. gundlachi), Ridgway's Hawk (Buteo ridgwayi), Puerto Rican Broad-winged Hawk (Buteo platypterus brunnescens), Newton's Screech-Owl (Otus nudipes newtoni), Lesser Antillean populations of the Burrowing Owl (Athene cunicularus), Stygian Owl (Asio stygius), and Jamaican Owl (Pseudoscops grammicus). There is concern that exotic parrots and European Starlings (Sturnus vulgaris) recently introduced to Puerto Rico may compete with American Kestrels (Falco sparverius) for cavity nest sites. Wintering populations of the Merlin (F. columbarius) and the Peregrine Falcon (F. peregrinus) continue to accumulate persistent pesticides in the West Indies where these chemicals are not controlled. The Puerto Rican Short-eared Owl (Asio flammeus) was formerly considered close to extinction, but has recently become more numerous and widespread. The status of these raptors, threats to their populations, and conservation efforts are discussed. Since the arrival of the first Europeans nearly 500 years ago, the West Indies have undergone extensive environmental changes that have adversely affected the region's avifauna. Habitat changes related to agricultural development have had the most severe and widespread impact on bird popu-lations. Man has introduced numerous competitors and predators of native birds that have further changed the character of the islands' ecosystems. Traditional shooting habits and superstitions have also had a severe detrimental effect on the avifauna of most islands. Several raptor species have been critically affected by these environmental changes. The objective of this paper is to update and expand on my earlier review (Wiley 1985) of the status and conservation of raptors in the West Indies. I have included those species or populations that regional conser-vationists consider currently threatened or that will likely encounter problems in the future.
The diurnal raptor community of a primary rain forest in French Guiana was studied, both around a small isolated village and far from any human settlement. Twenty species were found in large areas of unbroken forest and 6 additional species only near edges and clearings around the village. The comparison between hunted and non-hunted patches of otherwise similar virgin forest showed that even a moderate hunting pressure (i.e., for food by few people) significantly reduces both mean species richness of sample counts and density of most primary forest raptors. The largest species may eventually disappear. Other than regional avifaunas and local anno- tated lists, including birds of prey, I found no
The ICBP/IUCN Red Data Book lists as Threatened or Endangered five of the 82 species of Falconiformes and one of the 32 Strigiformes that breed in tropical South America. The White- collared Kite (Leucopternis forbesi), an endemic of the Atlantic coastal forests of Brazil, can be added to this list. Because vast areas of South America, most notably its tropical forests, have been inadequately surveyed and few studies have been carried out on raptor species or assemblages, our knowledge of the distribution and natural history of many raptor species, especially owls and forest-dwelling Falconifor- mes, is rudimentary at best. Most needed for conservation purposes is information on population den- sities, distribution, and reproductive biology that will tell us how large populations are and how fast they can reproduce. For most species, these data are anecdotal or nonexistent. Although the majority of South America's tropical raptors appear not to be globally threatened at present, more information is needed to confirm current assessments, recognize when species become threatened, and to move quickly and efficiently to address such threats.
Global warming and human-driven impacts are changing the World's ecological zones. This book applies the principles described in Bailey's Ecosystem Geography: From Ecoregions to Sites, 2nd ed. (Springer 2009, 1st ed. 1996) to describe and characterize the major terrestrial and aquatic ecological zones of the Earth. Bailey's system for classifying these zones has been adopted by major organizations such as the U.S. Forest Service and The Nature Conservancy and this book is a significant contribution to a long tradition of classifying and studying the world's ecological regions or ecoregions. It includes two color maps that show the major ecoregions of the continents and oceans. Also included are: - 106 illustrations with 55 in full color - A new chapter on mountains is included. - There are new sections that address concerns about how eco regions are changing under the relentless influence of humans and climate change - Another new feature is the discussion of using eco regional patterns to transfer research results and select sites for detecting climate change effects on ecosystem distribution - Use of ecoregional patterns to design monitoring networks and sustainable landscapes - Fire regimes in different regional ecosystems and their management implications.
A survey of the diurnal raptor community (46 resident species) at five altitudinal levels from 100 to 4600 m was made in Venezuela using 106 1-km2 sample quadrats and then compared with similar censuses (211 plots) in southwestern Colombia and eastern Ecuador. Six habitat types were defined and habitat preferences were measured from every encountered birds and from the association between individual abundances and the coverage of habitat types on plots. The overall species richness steeply declined with elevation in all three countries. The raptor community consisted mostly of tropical species that rapidly decreased in both abundance and frequency of occurrence with elevation. A small set of subtropical-temperate forest specialists partly replaced them at mid-elevation and only two species occurred in the paramo of Venezuela, against 5–7 in the other countries. Although originally the gradients were probably almost completely covered with forest, a large part of the raptor community is now composed of grassland species, three of them extending from the lowlands to the tree line. The relative impoverishment of the Venezuelan community, especially at upper levels, is attributed to a peninsular effect at the narrow extreme northern tip of the Andes and perhaps also to former forest fragmentation. Within some species, different subspecies had discrete altitudinal distributions and interspecific competition may explain differences in the range extension of some species between countries. Today, however, accelerating deforestation may result in a severe decline of forest-interior species and a probable reduction in the altitudinal range of at least some of them. Species naturally associated with forest gaps or edges usually tolerate a high degree of forest fragmentation and degradation but only one of them may become abundant in heavily human-altered woodlands. Few grassland specialists have become more widely distributed in the increasingly deforested landscapes.
Informaciones históricas y anecdóticas indican que de una fauna original de 14 especies de aves rapaces diurnas residentes en el valle medio del rio Cauca, Colombia, se han extinguido seis especies y dos mas se consideran amenazadas. Mientras que la disminucion de algunas especies se relaciona con la drástica reductión de hábitats originales tales como bosques y humedales, tres especies propias de hábitats abiertos también se han visto afectadas. Se identifican como probables factores la expansión de la agricultura intensiva (a expensas de las areas previamente dedicadas a la ganaderia), la contaminatión por agroquimicos, los conflictos con los intereses humanos y ciertos factores como el tamano corporal, la proximidad del valle medio del Cauca al limite superior de distributión altitudinal de estas especies y el relativo aislamiento del valle con respecto de la región del Caribe y de las sabanas al oriente de los Andes. Se relieva la necesidad de establecer programas de monitoreo de las faunas de vertebrados, inclufdas las especies consideradas como comunes en hábitats abiertos y perturbados.
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The distribution and density of diurnal raptors and large game birds were studied in the vast unbroken rain forest of French Guiana to bring some concrete data to the design of a national park Mainly by mapping the movements of raptors displaying over the canopy and estimating densities on understory strip transects, I tried to assess the species composition of I 1 2,500–ha plots of primary forest then to determine the actual population of a 10,000–ha area including all the major forest habitats Among 27 primary forest raptors 7 were recorded in all plots and 4 in only I or 2 plots. There was a near doubling of species with a tenfold increase in area but no 10,000–ha area and few 100,000–ha quadrats would include the full regional set of forest raptors A 10,000–ha plot included less than 100 pairs of diurnal raptors and only 23 species, 21 of which were represented by a mere I to 8 pairs. The three rarest species (harpy eagle, black caracara and orange‐breasted falcon) have extremely low densities and patchy distributions (on average 1 pair for 10,000 to 300,000‐ha), but narrow habitat selection or specialized diet are not the sole correlates of rarity. The dispute o w the best conservation strategy cannot be settled without a knowledge of the species' ecology that is currently lacking. Local patchiness and low dispersal ability usually argue for single large reserves, whereas some widely scattered species may be better protected in a network of smaller reserves According to the results and the (still unsupported) minimum size estimates of a viable population, the smallest Guianan rain forest reserve including a complete bird community should be somewhere between I and 10 million hectares Moreover, the large game birds were found to be high sensitive to hunting pressure even when it occurs around the protected area. Their seasonal movements make them especially vulnerable.
Demographic data from both breeding and non‐breeding periods are needed to manage populations of migratory birds, many of which are declining in abundance and are of conservation concern. Although habitat associations, and to a lesser extent, reproductive biology, are known for many migratory species, few studies have measured survival rates of these birds at different parts of their annual cycle.
Cormack–Jolly–Seber models and Akaike’s information criterion model selection were used to investigate seasonal variation in survival of a Nearctic – Neotropical migrant songbird, the black‐throated blue warbler, Dendroica caerulescens . Seasonal and annual survival were estimated from resightings of colour‐ringed individuals on breeding grounds in New Hampshire, USA from 1986 to 2000 and on winter quarters in Jamaica, West Indies from 1986 to 1999. Warblers were studied each year during the May–August breeding period in New Hampshire and during the October–March overwinter period in Jamaica.
In New Hampshire, males had higher annual survival (0·51 ± 0·03) and recapture probabilities (0·93 ± 0·03) than did females (survival: 0·40 ± 0·04; recapture: 0·87 ± 0·06). In Jamaica, annual survival (0·43 ± 0·03) and recapture (0·95 ± 0·04) probabilities did not differ between sexes. Annual survival and recapture probabilities of young birds (i.e. yearlings in New Hampshire and hatch‐year birds in Jamaica) did not differ from adults, indicating that from the time hatch‐year individuals acquire territories on winter quarters in mid‐October, they survive as well as adults within the same habitat.
Monthly survival probabilities during the summer (May–August) and winter (October–March) stationary periods were high: 1·0 for males in New Hampshire, and 0·99 ± 0·01 for males in Jamaica and for females in both locations.
These annual and seasonal survival estimates were used to calculate warbler survival for the migratory periods. Monthly survival probability during migration ranged from 0·77 to 0·81 ± 0·02. Thus, apparent mortality rates were at least 15 times higher during migration compared to that in the stationary periods, and more than 85% of apparent annual mortality of D. caerulescens occurred during migration.
Additional data from multiple species, especially measures of habitat‐specific demography and dispersal, will improve our understanding of the relative impacts of the breeding, migratory, and winter periods on population dynamics of migratory birds and thus enhance future conservation efforts.
The Galapagos Hawk Buteo galapagoensis is one of few species showing cooperative polyandry. As many as four males may mate with one female and share a territory and nest, Such groups, on average, produce more young than monogamous pairs, but on a per male basis (assuming that each male of a group has an equal chance to fertilize each young) polyandrous males produce fewer young per year than monogamous males. Territorial breeding birds show higher yearly survivorship (90%) than non-territorial, non-breeding birds (50% or less). All territorial birds seem to remain on their territories for life, and monogamous pairs actually constitute the remnants of polyandrous groups. Some potential factors producing such an unusual system are discussed. Limited breeding space and high mortality among non-territorial birds seem to work in favour of group breeding in this and other cooperative species. Polyandry may be favoured because of the reduced value of extra females in hawk breeding behaviour. Equal-status males may occur because of the lack of kinship among cooperating males and the high potential genetic cost of being a helper in a long-lived, low fecundity species. Other possible factors favouring group breeding are territory acquisition and the variable nature of the Galapagos climate.
A density index of every diurnal raptor species (Falconiformes) was obtained on 101 400 ha sample plots distributed among eight natural habitats and five man-made habitats arranged along gradients of increasing forest degradation and fragmentation. The most significant structural parameter affecting species distribution was the tall canopy forest cover. Species richness, diversity and density all decreased with this mature forest cover index. Individual species and overall community densities decreased along the deforestation gradient but the species richness was partly maintained by species turnover. Six groups of species were identified according to their natural habitat preferences. Their distribution along the deforestation gradient was correlated with their natural habitat selection pattern. Thus the community composition of each vegetation or landscape type was predictable. Fifty-six percent of the regional assemblage of species had their optimal density in the primary forest. A third of them were interior forest species highly sensitive to forest disturbance and opening. The other two-thirds were upper canopy, gap or edge species more tolerant to forest fragmentation. The last twenty-one species were associated with various coastal habitats, from dense forest patches to mangrove and savanna. Again, one third of them were strictly restricted to their specialized habitats while the last two-thirds colonized human-altered habitats and progressively replaced primary forest species with increasing deforestation. The maintenance of large areas of every natural habitat was essential for the conservation of (1) the whole population of a third of the total raptor diversity and (2) optimal and presumably potential source populations of most other species surviving in human-modified habitats.