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Survival of a small reintroduced griffon vulture population in the Apennines: Insights from Global Positioning System tracking
Abstract
Conservation translocations ( e. g., restocking, reintroductions) represent efficient tools to prevent the extinction or favouring the return of previously extirpated populations into the wild. Evaluating demographic parameters of translocated populations is a key issue to assess and monitor their conservation status and to provide evidences useful to implement management actions aimed at long-term conservation results. We report first data on survival estimates and related mortality causes for a reintroduced population of Eurasian griffon vultures ( Gyps fulvus) in the central-southern Apennine, Italy, from satellite telemetry data. Twenty vultures have been fitted with solar-powered Global Positioning System (GPS) tags in Pollino National Park (PNP, southern Italy, N = 9) and Monte Velino Reserve (MVR, central Italy, N = 11). Survival has been estimated on a total amount of 173,568 GPS fixes from December 2016 to October 2020 (1415 days) using the Fleming-Harrington estimator. Five, out of 20 vultures, died by poisoning (40%), collision with wind turbines (20%) and of unknown causes (40%). Two birds dispersed from MVR to France (though they later came back) and one from PNP to Croatia. Estimated survival rate across the whole study period was 0.709 (±0.11, SE; 0.523–0.961, 95% CI), and annual survival rate was 0.915 (±0.06, SE; 0.846–0.990, 95% CI). No significant differences in survival rates have been detected according to sex or age. As mortality in our study was mainly human-caused, we urge relevant institutions and agencies to strengthen and effectively establish anti-poison strategies, as well as implementing mitigation and prevention measures for the existing and planned wind farms. The establishment of a long-term viable population in the central-southern Apennines will depend upon both lower levels of human-caused mortality and habitat preservation.
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Wind turbines and power lines can cause bird mortality due to collision or electrocution. The biodiversity impacts of energy infrastructure (EI) can be minimised through effective landscape-scale planning and mitigation. The identification of high-vulnerability areas is urgently needed to assess potential cumulative impacts of EI while supporting the transition to zero carbon energy.
We collected GPS location data from 1,454 birds from 27 species susceptible to collision within Europe and North Africa and identified areas where tracked birds are most at risk of colliding with existing EI. Sensitivity to EI development was estimated for wind turbines and power lines by calculating the proportion of GPS flight locations at heights where birds were at risk of collision and accounting for species' specific susceptibility to collision. We mapped the maximum collision sensitivity value obtained across all species, in each 5 × 5 km grid cell, across Europe and North Africa. Vulnerability to collision was obtained by overlaying the sensitivity surfaces with density of wind turbines and transmission power lines.
Results: Exposure to risk varied across the 27 species, with some species flying consistently at heights where they risk collision. For areas with sufficient tracking data within Europe and North Africa, 13.6% of the area was classified as high sensitivity to wind turbines and 9.4% was classified as high sensitivity to transmission power lines. Sensitive areas were concentrated within important migratory corridors and along coastlines. Hotspots of vulnerability to collision with wind turbines and transmission power lines (2018 data) were scattered across the study region with highest concentrations occurring in central Europe, near the strait of Gibraltar and the Bosporus in Turkey.
Synthesis and applications. We identify the areas of Europe and North Africa that are most sensitive for the specific populations of birds for which sufficient GPS tracking data at high spatial resolution were available. We also map vulnerability hotspots where mitigation at existing EI should be prioritised to reduce collision risks. As tracking data availability improves our method could be applied to more species and areas to help reduce bird-EI conflicts.
Deployment of wind energy is proposed as a mechanism to reduce greenhouse gas emissions. Yet, wind energy and large birds, notably soaring raptors, both depend on suitable wind conditions. Conflicts in airspace use may thus arise due to the risks of collisions of birds with the blades of wind turbines. Using locations of GPS-tagged bearded vultures, a rare scavenging raptor reintroduced into the Alps, we built a spatially explicit model to predict potential areas of conflict with future wind turbine deployments in the Swiss Alps. We modelled the probability of bearded vultures flying within or below the rotor-swept zone of wind turbines as a function of wind and environmental conditions, including food supply. Seventy-four per cent of the GPS positions were collected below 200 m above ground level, i.e. where collisions could occur if wind turbines were present. Flight activity at potential risk of collision is concentrated on south-exposed mountainsides, especially in areas where ibex carcasses have a high occurrence probability, with critical areas covering vast expanses throughout the Swiss Alps. Our model provides a spatially explicit decision tool that will guide authorities and energy companies for planning the deployment of wind farms in a proactive manner to reduce risk to emblematic Alpine wildlife.
In recent decades, intensive techniques of livestock raising have flourished, which has largely replaced traditional farming practices such as transhumance. These changes may have affected scavengers’ behaviour and ecology, as extensive livestock is a key source of carrion. This study evaluates the spatial responses of avian scavengers to the seasonal movements of transhumant herds in south-eastern Spain. We surveyed the abundance of avian scavengers and ungulates, and analysed the factors affecting the space use by 30 GPS-tracked griffon vultures ( Gyps fulvus ). Griffons’ foraging activity increased in the pasturelands occupied by transhumant herds, which implied greater vulture abundance at the landscape level during the livestock season. In contrast, facultative scavengers were more abundant without transhumant livestock herds, and the abundance of wild ungulates did not change in relation to livestock presence. We conclude that fostering transhumance and other traditional farming systems, to the detriment of farming intensification, could favour vulture conservation.
Old World vultures are experiencing dramatic population declines and now are among the species most threatened with extinction. Understanding the environmental variables that can influence the reproductive indexes of vulture populations can facilitate both habitat and species management. The aim of this study was to identify which environmental variables primarily affect the breeding successes of the Griffon Vulture Gyps fulvus in the northern Sardinia Island by applying a Bayesian hierarchical model (BHM). A unique dataset of reproductive records (197 nests monitored over 39 years for a total of 992 breeding records) was used. Eight environmental and topographic variables describing the habitat at the nesting sites were considered as potential predictors of breeding success. These included mean annual temperature, mean annual precipitation, isothermality, elevation, the normalized difference vegetation index (NDVI), wind speed, and the aspect and slope of the land surface. In addition, we also considered the effect of human disturbance and the type of nest. According to our best model, the probability of successfully raising a chick in Griffon Vultures was higher in nests exposed to a high wind speed, not covered by natural shelters, where the vegetation was mostly represented by shrub and pastures, with low human disturbance and in years with low rainfall. This model will be useful to the management of the breeding habitat and to identify the area most suitable for Griffon Vulture reproduction. This information is crucial for programming conservation measures aimed at enlarging the area of occupancy of the species.
Conservation translocations are a widespread tool commonly used to prevent the extinction of species locally and globally. However, conservation transloca-tions are complicated operations which often fail, especially when they involve the release of captive-bred animals. In order to survive, translocated animals need to adapt to a new environment; the success of this adaptation depends, to a large extent, on the characteristics of the release environment and on early life experiences that can affect the animals' proficiencies. We tested the effects of different early life experiences and differences in the release environment on the survival of captive-bred translocated Griffon Vultures (Gyps fulvus) in Israel, where they are critically endangered. We used a mark-resight approach to calculate survival using a large dataset containing 9 years of observations of individually-marked vultures. We found that the Griffon Vultures' survival was positively affected by their age at release and the time they spent in the wild. We also found that survival was affected by rearing method, release site and release season. Our results emphasize the critical importance of the release protocol to the success of a conservation translocation project. Furthermore , our results show how events occurring during the entire pre-release period can have important repercussions many years later when the captive animal is released into the wild, but also that experience gained post-release plays a major role in the animals' survival. K E Y W O R D S captive breeding,
Events of non-natural mortality in human-dominated landscapes are especially challenging for populations of large vertebrates with K strategies. Among birds, vultures are one of the most threatened groups experiencing sharp population declines due to non-natural mortality. Factors causing non-natural mortality are usually studied separately. However, the potential use of an integrated index able to predict large-scale mortality risks of avian scavengers could be especially useful for planning conservation strategies. Here, we used the Human Footprint index to examine the impact of landscape anthropization on the survival rates of 66 GPS-tagged adult Eurasian griffon vultures (Gyps fulvus) in two Spanish regions. Foraging in more anthropized areas resulted in a significantly higher individual mortality risk mainly due to collisions with vehicles, poisonings, electrocutions and fatalities with wind turbines. Mean yearly survival rates were estimated at 0.817 ± 0.043 SE and 0.968 ± 0.018 SE for individuals from the more and less anthropized regions, respectively. Additional research should investigate whether some vulture populations could be acting as sinks unnoticed due to metapopulation dynamics. From a broader point of view, our study shows that a straightforward Human Footprint was a useful index to predict the survival of top scavengers and can be highly applicable to planning large-scale conservation measures.
Obtaining robust survival estimates is critical, but sample size limitations often result in imprecise estimates or the failure to obtain estimates for population subgroups. Concurrently, data are often recorded on incidental reencounters of marked individuals, but these incidental data are often unused in survival analyses. We evaluated the utility of supplementing a traditional survival dataset with incidental data on marked individuals that were collected ad hoc. We used a continuous time‐to‐event exponential survival model to leverage the matching information contained in both datasets and assessed differences in survival among adult and juvenile and resident and translocated Mojave desert tortoises (Gopherus agassizii). Incorporation of the incidental mark‐encounter data improved precision of all annual survival point estimates, with a 3.4%–37.5% reduction in the spread of the 95% Bayesian credible intervals. We were able to estimate annual survival for three subgroup combinations that were previously inestimable. Point estimates between the radiotelemetry and combined datasets were within |0.029| percentage points of each other, suggesting minimal to no bias induced by the incidental data. Annual survival rates were high (>0.89) for resident adult and juvenile tortoises in both study sites and for translocated adults in the southern site. Annual survival rates for translocated juveniles at both sites and translocated adults in the northern site were between 0.73 and 0.76. At both sites, translocated adults and juveniles had significantly lower survival than resident adults. High mortality in the northern site was driven primarily by a single pulse in mortalities. Using exponential survival models to leverage matching information across traditional survival studies and incidental data on marked individuals may serve as a useful tool to improve the precision and estimability of survival rates. This can improve the efficacy of understanding basic population ecology and population monitoring for imperiled species. Survival estimation using radio‐telemetry datasets is often hampered by small sample size. We found that combining incidental sighting data on marked individuals with radio‐telemetry data improved survival estimation by reducing the spread of 95% credible intervals in all cases with minimal and inconsistent effects on point estimates. In three of eight sub‐groups, survival estimates were only obtainable after inclusion of the incidental encounter data.
XX CIO - 26/29 settembre 2019 - Napoli
Contributo Simposio: Gli avvoltoi in Italia, status, minacce e conservazione
Avian biologists routinely estimate sampling variance for parameter estimates such as daily nest survival, fecundity, annual survival, and density. However, many biologists are not certain of methods to derive sampling variance for parameters when survival rates change temporal scales. Similar methods are needed to obtain sampling variance when biologists combine parameter estimates to calculate an indirect demographic parameter, such as population growth rate. The delta method is a useful technique for approximating sampling variance when the desired demographic parameter is a function of at least one other demographic parameter. However, the delta method is rarely taught in most graduate-level biology or ecology courses, and application of this method may be discouraged by seemingly daunting formulas in reference books. Here, I provide five examples of sampling variance approximations for common situations encountered by avian ecologists, with step-by-step explanations of the equations involved.
Vulture conservation: the case for urgent action - Volume 29 Issue 1 - ROGER SAFFORD, JOVAN ANDEVSKI, ANDRE BOTHA, CHRISTOPHER G. R. BOWDEN, NICOLA CROCKFORD, REBECCA GARBETT, ANTONI MARGALIDA, IVÁN RAMÍREZ, MOHAMMED SHOBRAK, JOSÉ TAVARES, NICK P. WILLIAMS
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.
Aim
Farmland abandonment or “ecological rewilding” shapes species distribution and ecological process ultimately affecting the biodiversity and functionality of ecosystems. Land abandonment predictions based on alternative future socioeconomic scenarios allow foretell the future of biota in Europe. From here, we predict how these forecasts may affect large‐scale distribution of the Cinereous vulture (Aegypius monachus), an apex scavenger closely linked to Mediterranean agro‐grazing systems.
Location
Iberian Peninsula.
Methods
Firstly, we modelled nest‐site and foraging habitat selection in relation to variables quantifying physiography, trophic resources and human disturbance. Secondly, we evaluate to what extent land abandonment may affect the life traits of the species and finally we determined how potential future distribution of the species would vary according to asymmetric socioeconomic land‐abandonment predictions for year 2040.
Results
Cinereous vultures selected breeding areas with steep slopes and low human presence whereas foraging areas are characterized by high abundance of European rabbits (Oryctolagus cuniculus) and wild ungulates. Liberalization of the Common Agricultural Policy (CAP) could potentially transform positively 66% of the current nesting habitat, favouring the recovery of mature forest. Contrarily, land abandonment would negatively affect the 63% of the current foraging habitat reducing the availability of preferred food resources (wild European rabbit). On the other hand, the maintenance of the CAP would determine lower frequencies (24%–22%) of nesting and foraging habitat change.
Main conclusions
Land abandonment may result into opposite effects on the focal species because of the increase in nesting habitats and wild ungulates populations and, on the other hand, lower availability of open areas with poorer densities of European rabbits. Land‐abandonment models’ scenarios are still coarse‐grained; the apparition of new human uses in natural areas may take place at small‐sized and medium‐sized scales, ultimately adding complexity to the prediction on the future of biota and ecosystems.
Full downloadable pdf available free of charge here:
http://www.cms.int/raptors/en/publication/multi-species-action-plan-conserve-african-eurasian-vultures-vulture-msap
Vultures constitute an important functional group in many ecosystems, providing crucial ecosystem services both in natural and humanized environments. These scavengers are facing massive declines worldwide, but in several African countries virtually nothing is known on populations’ status and threats, hampering the development of adequate conservation strategies. In Guinea-Bissau, globally important populations of Hooded Necrosyrtes monachus and African white-backed vultures Gyps africanus were recently reported. Using the country as a study area, we aim to characterize human-vulture interactions in West Africa applying a multidisciplinary approach. We assessed the status and distribution of vulture populations using data from 1711 km of roadside transects, examined predictors of their distribution, and produced a nationwide population estimate for the Hooded Vulture, using an innovative method based on the relationship between the size of human population in settlements and vulture numbers. We conducted 47 stakeholder interviews to assess perceived roles played by vultures, and to investigate potential anthropogenic threats. Hooded vultures were strongly associated with high human population densities, whereas no relation was found between African white-backed and Rüppell’s vultures and any of the tested predictors, which included cattle density, precipitation and Normalized Difference Vegetation Index, among others. We estimate a national population of 43347 Hooded vultures, the largest population reported in the species range. Respondents were generally aware of the services provided by vultures, especially waste and carcass removal, including in urban areas. Hunting for witchcraft and traditional medicine was the most frequently recognised threat, while poisoning was ranked as having the highest impact. We hypothesise that poisoning-related mortality may be affecting African white-backed and Rüppell’s vultures’ distribution and explain their scarcity in apparently highly suitable habitats. Our results suggest a mutualistic rather than a commensalistic relationship between vultures and humans, with important implications for designing and implementing conservation strategies.
L'alimentazione supplementare è uno strumento diffuso per la gestione delle popolazioni di uccelli necrofagi, sia obbligati (avvoltoi) che facoltativi (e.g. nibbi). Nonostante i vantaggi, ad esempio nelle prime fasi di una reintroduzione, la letteratura evidenzia alcune criticità di questa prassi, suggerendo di modulare l'apporto di cibo (quantità, frequenza) in relazione a fattori ambientali, alla fenologia e in stretta relazione alla specie target (specialmente quando esistano comunità di necrofagi composte da diverse specie). Il monitoraggio dell'uso dei punti di alimentazione artificiale è pertanto propedeutico alla valutazione della loro efficacia e del loro utilizzo da parte delle specie target sia in termini generali che in riferimento alle differenze individuali o tra le diverse coorti (sesso, età), rispetto al ciclo biologico e in relazione al successo riproduttivo. Nella Riserva Naturale Orientata Monte Velino, sin dalle prime fasi della reintroduzione del grifone (Gyps fulvus Hablizl, 1783), è stato allestito un punto di alimentazione supplementare (o carnaio) per favorire l'insediamento e minimizzare la dispersione degli avvoltoi rilasciati dal 1994 al 2002 (93 individui donati dal Governo Spagnolo, in media 10 avvoltoi liberati ogni anno). L'obiettivo di questo monitoraggio, di cui vengono esposti alcuni risultati preliminari e che è parte di una ricerca più ampia, è quello di valutare, anche in combinazione con altri metodi di studio, la dinamica di utilizzo del carnaio da parte dei grifoni e le differenze nell'utilizzo su base individuale, stagionale e rispetto al ciclo biologico. Lo scopo ultimo del monitoraggio è quindi quello di definire il pattern ottimale di somministrazione dell'alimentazione suppletiva per massimizzare i vantaggi di questa pratica gestionale e renderla nel complesso più efficiente e mirata, valutando altresì da una prospettiva gestionale ed etica l'opportunità e l'utilità dell'alimentazione artificiale. Il grifone (Gyps fulvus) nell'Appennino: differenze individuali nell'utilizzo del punto di alimentazione supplementare RISULTATI In 33 mesi il punto di alimentazione è stato allestito 274 volte, 8,3/mese (5-11; DS ±1,29), con un apporto ponderale medio pari a 2,26 q.li/mese (13,5-34,8; DS ±0,62). L'86% dei carnai allestiti (N=237) è stato monitorato con una fototrappola idonea alla lettura degli anelli e l'89% dei carnai monitorati (N=212) è stato frequentato dai grifoni. Dei 109 avvoltoi inanellati nel periodo di studio 9 (8.25%) sono stati avvistati in altre aree (Francia, Spagna e Calabria). Al carnaio sono stati avvistati 99 dei 109 grifoni inanellati, e in 204 carnai (96%) sui 212 monitorati e frequentati dai grifoni, sono stati identificati 130 grifoni con anelli colorati, compresi individui provenienti dall'estero (Spagna, Francia, Croazia, Portogallo), dalla Calabria e dal Friuli. In media sono stati identificati 9,2 grifoni marcati per ogni carnaio allestito (0-29; DS ± 6,7). La frequenza di osservazione media (±ds) dei grifoni marcati, evidenzia un uso relativamente limitato del carnaio da parte della maggior parte degli individui: Fo corr = 18% (±21); Fo= 15 (±13) (figura 1-A, B). Inoltre, la relazione tra numero di carnai potenzialmente disponibili e frequenza di osservazione del punto di alimentazione su base individuale (Fo corr e Fo) suggerisce come per un numero di carnai disponibile simile, la frequenza di osservazione sia decisamente variabile tra gli individui (figura 2-A,B). Tale relazione è graficamente evidente indipendentemente dalla quantità di carnai disponibile considerata. CONCLUSIONI Sebbene l'analisi delle differenze individuali nell'utilizzo del carnaio sia ancora in una fase preliminare, sono evidenti forti disparità di utilizzo del punto di alimentazione da parte dei diversi grifoni. Queste differenze, oltre a riferirsi potenzialmente a strategie di alimentazione individuali differenti, indipendenti da altri fattori (cosa singolare per una specie fortemente gregaria) potrebbero dipendere da altre cause come: • lo status riproduttivo, • l'età e la suscettibilità alla dispersione, • il luogo d'origine degli individui, • il sesso, • la stagione e l'anno, • la distanza tra il carnaio e il sito riproduttivo o il roost abituale, • lo stato nutrizionale degli individui e la quantità di cibo fornito. Tali elementi verranno considerati successivamente, includendo nel campione anche gli ulteriori rilievi in corso. MATERIALI E METODI Il punto di alimentazione supplementare, ubicato nella RNO Monte Velino in Comune di Magliano de'Marsi (AQ), viene monitorato con una fototrappola dal 2010. Tuttavia, poiché solo dal 2014 è stato possibile avviare un ampio progetto di marcatura dei grifoni con anelli colorati (oltre 120 individui inanellati dal 2014 al 2016 a cui si sommano individui stranieri già dotati di analoghe marcature), i risultati presentati si riferiscono all'osservazione e riconoscimento dei grifoni al carnaio da agosto 2014 ad aprile 2017. Per ogni allestimento del punto di alimentazione sono state analizzate le immagini scattate (anche >100/allestimento) dalla fototrappola e sono state identificate le sigle degli anelli colorati, registrando in un data base la presenza dei singoli individui. In questo modo è stata calcolata la frequenza di osservazione (Fo) al carnaio di ogni grifone marcato. Poiché i grifoni sono stati inanellati nel corso di tre anni, la frequenza di osservazione è stata poi corretta per ogni avvoltoio sulla base della data di inanellamento (Fo corr) e riportata in percentuale come Fo/numero carnai potenzialmente frequentabili (i.e. allestiti successivamente all'inanellamento di un determinato individuo). Figura 1A Figura 1B Figura 2B Figura 2A BIBLIOGRAFIA-Michael O. C., 2016-Vultures, their Evolution, Ecology and Conservation;-Puddu G. et al., 2016-I carnai per la conservazione dei rapaci, Gazzetta ambiente.
Remotely-sensed and bottom-up survey information were compiled on eight variables measuring the direct and indirect human pressures on the environment globally in 1993 and 2009. This represents not only the most current information of its type, but also the first temporally-consistent set of Human Footprint maps. Data on human pressures were acquired or developed for: 1) built environments, 2) population density, 3) electric infrastructure, 4) crop lands, 5) pasture lands, 6) roads, 7) railways, and 8) navigable waterways. Pressures were then overlaid to create the standardized Human Footprint maps for all non-Antarctic land areas. A validation analysis using scored pressures from 3114×1 km(2) random sample plots revealed strong agreement with the Human Footprint maps. We anticipate that the Human Footprint maps will find a range of uses as proxies for human disturbance of natural systems. The updated maps should provide an increased understanding of the human pressures that drive macro-ecological patterns, as well as for tracking environmental change and informing conservation science and application.
Sex ratio is a parameter worth to be monitored in small animal populations, as it has wide implications for their conservation. Morphological sex identification in birds, especially in the Accipitridae, can be difficult if the animals are young or when there is no appreciable sexual dimorphism. Sex determination can be impossible when few and/or degraded biological material (e.g. feathers, blood traces, decomposed carcasses) is available. In this case, molecular markers represent the analytical method of choice. Two molecular Amplification Refractory Mutation System (ARMS) protocols, both based on the amplification of portions of the Chromo-Helicase DNA-binding protein (CHD1) gene, were tested on tissues from 6 Griffon vultures Gyps fulvus of known sex, and subsequently, on 9 shed feathers (i.e. degraded samples from individuals of unknown sex) collected on feeding sites. Protocol 1 consisted of one PCR reaction yielding two amplicons with larger sizes than those produced with Protocol 2, which, in contrast, consisted of two PCRs. Our results show that, overall, both molecular protocols are suitable for sex identification in the Griffon vulture. In particular, when good quality/quantity DNA is available (e.g. DNA from feathers of live animals, fresh or frozen blood and tissues), Protocol 1 was faster than Protocol 2, since one single PCR is performed. On the other hand, Protocol 2 can better suite to poor or degraded DNA (e.g. extracted from shed feathers or decomposed tissues), because the two amplifications produce smaller fragments. We selected Protocol 1 to analyse good quality DNA from feathers of 89 free-ranging Griffons, sampled during capture and ringing activities (years 2013-2015) by the Forest Service within the Monte Velino Reserve (central Apennines, Italy). The sex ratio obtained for this reintroduced population was 1: 2.07 (29 females and 60 males). We also explored the potential of applying this method in other 10 bird species: molecular and morphological identification of sex always yielded concordant results. This study shows that Protocol 1 can be used for sex identification in Griffons and other mainly monomorphic species for which population studies or monitoring programs are planned, or when sex could not be determined from few remains of otherwise dimorphic species.
Due to the potentially detrimental consequences of low performance in basic functional tasks, individuals are expected to improve performance with age and show the most marked changes during early stages of life. Soaring-gliding birds use rising-air columns (thermals) to reduce energy expenditure allocated to flight. We offer a framework to evaluate thermal soaring performance, and use GPS-tracking to study movements of Eurasian griffon vultures (Gyps fulvus). Because the location and intensity of thermals are variable, we hypothesized that soaring performance would improve with experience and predicted that the performance of inexperienced individuals (<2 months) would be inferior to that of experienced ones (>5 years). No differences were found in body characteristics, climb rates under low wind shear, and thermal selection, presumably due to vultures’ tendency to forage in mixed-age groups. Adults, however, outperformed juveniles in their ability to adjust fine-scale movements under challenging conditions, as juveniles had lower climb rates under intermediate wind shear, particularly on the lee-side of thermal columns. Juveniles were also less efficient along the route both in terms of time and energy. The consequences of these handicaps are probably exacerbated if juveniles lag behind adults in finding and approaching food.
Zoology 53-2207 QL696 2014-35370 CIP Campbell, Michael O'Neal. Vultures: their evolution, ecology and conservation. CRC Press, 2015. 364p bibl index afp ISBN 9781482223613, $103.96; ISBN 9781482223620 ebook, $90.97. This authoritative volume provides detailed information on all vultures of the world, including condors. Campbell's thorough review of the literature is reflected in the 188-page bibliography (some 3,700 references, cited throughout). Part 1, "Vulture Classification, Genetics and Ecology," provides overviews of all species. For each, Campbell (Simon Fraser Univ.) provides details of physical appearance, classification, foraging and breeding behavior, population status, and a concluding essay. Graphics include color illustrations of each (and its egg) and a range map. Part 2 is titled "Vulture Ecology and Evolution." Part 3, "Vulture Ecology and Conservation," includes an invaluable discussion of the current catastrophic decline of Indian (and other) vultures due to ingestion of chemicals, especially diclofenac and lead. Campbell also discusses other threats to vultures: collisions with aircraft, wind turbines, habitat incursions (including urbanization), and human attitudes toward vultures. The somewhat pedantic, academic style makes for some awkward reading, but this is relieved by the volume's illustrations and good formatting (e.g., chapter subheadings). This fine volume joins Vulture Biology and Management (1983), W. R. Wilbur and J. A. Jackson's excellent (albeit dated) edited volume.
The R Commander graphical user interface to R is extensible via plug-in packages, which integrate seamlessly with the R Commander's menu structure, data, and model handling. The paper describes the RcmdrPlugin.survival package, which makes many of the facilities of the survival package for R available through the R Commander, including Cox and parametric survival models. We explain the structure, capabilities, and limitations of this plug-in package and illustrate its use.
Reviews, in four steps, mathematical models of the dynamics of bird populations which are relevant to conservation and management: 1) demographic models with constant parameters, with an emphasis on sensitivity analysis and on the comparison of model results with population censuses; 2) environmental variability and its effect on population growth rate; 3) density-dependent models, with comments on the difficulties to assess density dependence using censuses; and 4) models incorporating density dependence, spatial aspects, and various kinds of stochasticity. -from Authors
Summary. Home range and movements of Griffon Vulture Gyps fulvus in the central
Apennines.
The Griffon Vulture Gyps fulvus widely occurs through Southern Europe, but
information on its space use are limited. Since 2010 the Italian Forest Service
in cooperation with other agencies and NGOs is carrying on a research on a
reintroduced population of griffon vultures in the central Apennines, to acquire
information about ranging behavior and use of carrions. From November 2010 to
November 2011 we trapped 76 vultures within 3 capture sessions (12, 36 and 28
birds). Transmitters acquired on average 3 (SD±0.9) validated positions/day for
15 adult vultures equipped with GPS tags. Birds yielded a total of 2,259 telemetry
days (November 2010-February 2012) and 6,985 validated GPS positions have
been recorded (57.8% of total fixes). Mean number of telemetry days/vulture
(151; SD±115.5; 8-356) resulted in 466 positions/bird (33-1,428; SD±398).
Mean home range size (Minimum Convex Polygon) has been 3,044 km2
(SD±1,481). Summer home range size (2,623 km2) and mean daily movements
(37 km; SD±13.4) were significantly wider compared to winter (1,531 km2)
(χ2=5.23; P=0.02) (19 km; SD±6.8) (χ2=9.63; P<0.005). Cumulative home
range spans across 7,600 km2, from Matese to Monti Sibillini massifs, covering
6 administrative regions. More frequently used territories (ca. 3,500 km2) were
mainly located north and especially south of L’Aquila city from Gran Sasso
massif (north) to Velino-Duchessa mountains extending around Fucino basin
until Simbruini-Ernici massifs and including the upper Liri valley. Eighty-seven
% of fixes could be found within protected areas, special protection areas and
important bird areas, but no particular or explicit management measures exist
for the conservation of such a vulture there. We recommend addressing specific
conservation strategies like the recent ban of lead ammunitions in the Abruzzo
region in those municipalities where more often griffon vultures occur and feed.
Knowledge of age-specific survival of deer (Odocoileus spp.) and the underlying causes of mortality are essential to our understanding of their population dynamics. We examined age-specific survival and cause-specific mortality of female white-tailed deer (O. virginianus) in an area where wolves (Canis lupus) recently had become reestablished and assessed the influence of winter severity during 1991-1996 using new survival analysis procedures. Sufficient data permitted rigorous survival analyses on 153 of 179 radiocollared females ≥0.6 years old, whose age distribution remained stable with annual median ages of 5.9-6.7 years old during the last 5 years of the study. Winter severities ranged from unusually mild to historically severe; 84% (81 of 97) of all mortalities occurred during November-May. The median age of deer survival according to the iterative Nelson estimator (INE) was 3.6 years (90% confidence limits [CL] = 2.4, 4.0). The smoothed estimate of the hazard function was a U-shaped curve with an elevated risk of mortality at 0.6 years old, which declined progressively until 5 years old, then increased steadily with the highest age-specific risk of death for deer ≥10 years old. Fits of the Anderson-Gill (AG) proportional hazards model to our data indicated that survival was negatively associated (P
The first part of this paper provides advice on buying or building equipment, on attaching transmitters to raptors and on field techniques. Three attachment methods are described, and data are given on weight, range and life limitations of transmitter packages. The second part describes the types of information available from the radio-tracking of raptors, to investigate movements, range-sizes and habitat-use, prédation, the survival of released birds and the population dynamics of wild raptors. Other applications have included the use of transmitters with sensors which modulate the radio signal, for telemetry of foraging and incubation behaviour.
Molt patterns are poorly understood in most large bird species; however, they are of paramount importance in the development of surveys in which age is a key parameter. From 2000 to 2011, we studied the body condition and molt patterns of 214 Griffon Vultures (Gyps fulvus) in Spain. Adult Griffon Vultures (“griffons”) demonstrated a poor body condition in winter during the incubation period, which then improved after hatching. Conversely, subadults were fairly uniform throughout the year, with their condition slightly inferior to that of adults all year around except the incubation period. The molt period lasted from April to December, ending in winter. Juveniles started their first molt in May of their second calendar year, beginning from the innermost primary (pp1) and proceeding outwards. Later, in midsummer, some individuals molted secondaries (only 17% of secondaries were molted in the first molt season) beginning at four foci: from the innermost (ss25) outwards, the outermost (ss1) and ss5 or ss6 inwards, and centrifugally from ss12. In the third calendar year, griffons continued molting primaries outwards in an orderly fashion and two new foci appeared in secondaries, apparently at ss6 and ss15. Most juvenile feathers were completely molted by the fourth calendar year, although some fifth-calendar-year griffons had retained juvenile secondaries. Subsequently, adults did not show a consistent molt pattern, but had a high degree of asymmetry between the two wings. Some quills were molted more often than others and this led us to hypothesize that adult griffons might molt quills on demand.
Feeding stations are commonly used to sustain conservation programs of scavengers but their impact on behaviour is still debated. They increase the temporal and spatial predictability of food resources while scavengers have supposedly evolved to search for unpredictable resources. In the Grands Causses (France), a reintroduced population of Griffon vultures Gyps fulvus can find carcasses at three types of sites: 1. “light feeding stations”, where farmers can drop carcasses at their farm (spatially predictable), 2. “heavy feeding stations”, where carcasses from nearby farms are concentrated (spatially and temporally predictable) and 3. open grasslands, where resources are randomly distributed (unpredictable). The impact of feeding stations on vulture’s foraging behaviour was investigated using 28 GPS-tracked vultures. The average home range size was maximal in spring (1272±752 km2) and minimal in winter (473±237 km2) and was highly variable among individuals. Analyses of home range characteristics and feeding habitat selection via compositional analysis showed that feeding stations were always preferred compared to the rest of the habitat where vultures can find unpredictable resources. Feeding stations were particularly used when resources were scarce (summer) or when flight conditions were poor (winter), limiting long-ranging movements. However, when flight conditions were optimal, home ranges also encompassed large areas of grassland where vultures could find unpredictable resources, suggesting that vultures did not lose their natural ability to forage on unpredictable resources, even when feeding stations were available. However during seasons when food abundance and flight conditions were not limited, vultures seemed to favour light over heavy feeding stations, probably because of the reduced intraspecific competition and a pattern closer to the natural dispersion of resources in the landscape. Light feeding stations are interesting tools for managing food resources, but don’t prevent vultures to feed at other places with possibly high risk of intoxication (poison).
A field study of the breeding behaviour of griffon vultures (Gyps fulvus)
was conducted in Crete (Greece) during 1997-2000. The main behavioural pat-terns examined were aerial displays, nest defence, copulation, nest building,
brooding and food provisioning to the chicks. The nesting territory consisted of a
semicircle ca 5 m radius around the nest that was defended against conspecifics.
Copulation attempts mainly occurred in the nesting ledge with a success rate of
77%. On average every pair accomplished 0.16 ± 0.34 copulations per day (range
= 0-4) while 3.3% of the total attempts accounted for extra-pair copulations. Sup-plying material to the nest started 32 ± 9 days prior to egg laying (range = 17-44)
at a rate of 5 ± 3.52 bouts/pair/day (range = 1-14). The mean number of items The mean number of items
added to the eyrie was 2 ± 1.3/bout/pair (range = 1-8) with 63.5% of these being 63.5% of these being
soft greenery. The mean frequency of relief at the nest relieves was 0.5 ± 0.64 . The mean frequency of relief at the nest relieves was 0.5 ± 0.64 The mean frequency of relief at the nest relieves was 0.5 ± 0.64
bouts/pair/day (range = 0-2) while an incubation shift lasted on average 37.4 ±
0.5 hr (range = 25.6-50.2 hr). Nest attendance by breeding birds was continu-ous during the first 2 months after the hatching of the egg, dropping to 35% of
daytime hours before fledging. Adult griffons foraged on average every other day
while food delivery rate to the chick was calculated at 1.9 ± 1.09 bouts/pair/day delivery rate to the chick was calculated at 1.9 ± 1.09 bouts/pair/day
(range = 1-4). The most critical period of the reproductive cycle was May when
chicks (6-10 weeks old) grew at their fastest rate and parent birds foraged on
alternate days. Differences in behavioural patterns among this insular population
and continental ones were minimal.
In the present study we describe the morphometrics of 97 live Eurasian Griffon Vultures Gyps fulvus collected on the island of Crete (Greece) and a sex determination model on the basis of various field techniques and multivariate data analysis. We determined the sex of 49 individuals with sex-specific DNA markers and polymerase chain reaction using DNA extracted from blood samples. Adult birds were generally larger than young ones with the wing chord being the only significantly different character. Male Griffons were smaller than females for most body characters and significantly larger (c. 3–5%) for head length, head width, bill length and bill length including the cere. A stepwise discriminant function analysis showed a high predictive power in gender determination by classifying 94.1% of the individuals of known sex that was not reduced by a jackknife cross-validation technique.
Avian biologists routinely estimate sampling variance for parameter estimates such as daily nest survival, fecundity, annual survival, and density. However, many biologists are not certain of methods to derive sampling variance for parameters when survival rates change temporal scales. Similar methods are needed to obtain sampling variance when biologists combine parameter estimates to calculate an indirect demographic parameter, such as population growth rate. The delta method is a useful technique for approximating sampling variance when the desired demographic parameter is a function of at least one other demographic parameter. However, the delta method is rarely taught in most graduate-level biology or ecology courses, and application of this method may be discouraged by seemingly daunting formulas in reference books. Here, I provide five examples of sampling variance approximations for common situations encountered by avian ecologists, with step-by-step explanations of the equations involved.
Biologists often use more than one marking technique in wildlife studies. For each of the mark types, it is common to conduct
a separate analysis of the recapture data to estimate parameters of interest, such as survival rates. Two data types that
can be used in estimating survival rates are resighting and radiotelemetry data. The Cormack-Jolly-Seber model is commonly
used to analyze the resighting data, while the Kaplan-Meier product limit estimator, modified for staggered entry of animals,
is used to analyze the radi otelemetry data. In a study where some animals receive two types of tags and others receive just
one tag type, the separate Cormack-Jolly-Seber and Kaplan-Meier analyses do not exploit all of the information in the combined
data sets. In this article, we propose a model and likelihood for the combined analysis of resighting and radi otelemetry
data. In comparison with the separate analyses, this richer model provides more information about the biology and sampling
processes. For example, the richer model permits assessment of assumptions required by the separate analyses and allows estimation
of additional parameters. We apply the model to annual resighting and monthly telemetry data from a population of snail kites
in Florida. The snail kite is a threatened species of bird in the United States, and our results on survival are very important.
In this example, all birds are marked using leg bands and some of them receive radios.
Capsule
The Eurasian Griffon Vulture Gyps fulvus is an obligate scavenger relying on spatially and temporally unpredictable food resources. We demonstrate how high-frequency telemetry data can be efficiently used to identify vultures’ feeding locations in the wild and study their diet.
Aims
To study the Griffon Vulture diet composition, seasonal variations, and bathing frequency in an area with high natural food availability.
Methods
We used a remote-sensing technique based on GPS and accelerometry data to identify the feeding locations, and ground-truthing to identify the carcass species and investigate the causes of mortality.
Results
We identified 13 taxa in the diet of Griffon Vultures. Cattle comprised 48.5% of the diet, followed by sheep (24.3%), while wild animals were 13.1%. We observed seasonal variation in the proportion of small stock and game species in the diet. Predation was reported as the main cause of mortality (60.2%) for prey species, while natural causes accounted for 37.6%. Vultures were mainly feeding in areas south of their breeding colonies in Bulgaria and Greece. Natural springs and fountains were regularly used by the Griffon Vultures for bathing and drinking, especially in the summer.
Conclusions
Free-ranging livestock creates favourable feeding conditions for vultures, especially in areas with rugged terrain and a high density of predators. An increase in the number of wild ungulates can potentially buffer the fluctuations in livestock numbers and be beneficial for vultures, especially in the autumn and winter months. Lead ammunition must be substituted with non-toxic alternatives to reduce the exposure of vultures and other scavengers to lead poisoning.
Delayed maturity and low reproductive rate make raptors naturally sensitive to high mortality rates, yet a wide variety of human-related threats negatively affect their population dynamics and persistence over time. We modelled the variability in the proximate causes of mortality associated with six species of large migratory raptors characterized by different ecological traits. We tested the hypothesis that species-specific mortality signals occur owing to differential exposure to threats in space and time. We relied on an unprecedently large dataset of ring (band) recovery (31269 records) over a period of > 100 years. Our findings suggested that mortality of these birds has declined dramatically since the late 1970s. We found species-specific seasonal patterns of mortality, with higher mortality rates during early life-stages. For Black Kite, Common Buzzard, and Osprey, mortality increased with distance travelled and decreased with distance from migratory bottlenecks. Human-related mortality was higher than natural mortality (47% vs 5.6%), but after 1979 indirect anthropogenic factors increased, while direct ones decreased. Raptors showed differential specific exposure to mortality causes (direct human: Honey Buzzard, Marsh Harrier; indirect human: Common Buzzard, Black Kite; direct and indirect human: Osprey; natural: Montagu’s Harrier). Conservation efforts and international laws have helped lower mortality caused directly by humans, but new emerging human-related threats are impacting migratory raptors and call for advanced conservation efforts. In a fast-changing world, anticipating future threats is key to stemming losses and boosting future preservation.
Although the population of Griffon Vulture Gyps fulvus is significantly increasing in Europe, in Italy the species is still on the Red List as ‘Critically Endangered’, with the last natural population persisting on the island of Sardinia. Several episodes of poisoning hampered the success of conservation actions implemented in the years 1987–1995. In 2005 there were estimated to be only 31–32 territorial pairs, with the population occupying the territories of Alghero and Bosa. We used a long-term dataset of reproductive records from the Sardinian Griffon Vulture populations to run a population viability analysis (PVA) to evaluate the extinction risk using the Vortex simulation software. The model estimated the probability of extinction over the next five generations (estimated generation time: 11 years, simulation time used: 55 years) as 96.4% for the Alghero population, and near-zero for the Bosa population. We used sensitivity analyses to understand how uncertainty about parameter values affect model outcomes. Population projections were evaluated under different management scenarios tackling the main threats (poisoning and human disturbance) and implementing conservation actions (supplementary feeding and restocking). Our results showed that population size is a critical factor in affecting the projections of population dynamics of Griffon Vultures. Sensitivity analyses highlighted the importance of poisoning events to population persistence and showed that juvenile and adult mortality rates had a secondary impact on population viability. The only conservation measure effective in significantly increasing stochastic growth rates in the Alghero population, whose initial population was set at five individuals, was the complete removal of poisoning events. When targeting the Bosa population (initial population size 94 individuals), supplementary feeding, mitigation of the risk of poisoning episodes, restocking, and mitigation of human disturbance in the reproductive sites significantly increased stochastic growth rate. A cost-effectiveness analysis should be performed to prioritise interventions.
The movements and spatial ecology of non-breeding Eurasian Griffon Vultures Gyps fulvus in northern Italy, Croatia and Austria do not seem to be affected by feeding station use. The purpose of this study was to assess how the creation of a feeding station at the Riserva Naturale Regionale del Lago di Cornino (Forgaria nel Friuli, northeast Italy) during the 1980s might have affected the spatial and behavioural ecology of the Eurasian Griffon Vulture. Using global positioning system (GPS) satellite tracking, we studied movements of nine non-breeding Eurasian Griffon Vultures within the Riserva Naturale Regionale del Lago di Cornino in Italy, the Hohe Tauern in Austria and the Kvarner Gulf in Croatia. Both the average foraging range size and the time spent by the birds in Italy were comparable to those recorded in Croatia and Austria, where the vultures depend on unpredictable food resources. A significant difference in terms of foraging range size was recorded among seasons. In winter it seems to be smaller as a consequence of reduced movements performed by the individuals due to harsh climate conditions. Our results suggest that the creation of a feeding station in Forgaria does not seem to have affected the spatial ecology of the Eurasian Griffon Vulture. However, due to the limited sample size and the young age of the individuals monitored, which have a long dispersal period, the findings presented should be considered as preliminary. Further research needs to be implemented to inform decisions regarding the management of supplementary feeding stations to promote the recovery and conservation of scavenger species, particularly in areas in which they have declined massively.
Capsule: In Griffon Vultures Gyps fulvus both parents take part in all parenting tasks but males take a significantly larger part of the burden.
Reintroduction biology is a field of scientific research that aims to inform translocations of endangered species. We review two decades of published literature to evaluate whether reintroduction science is evolving in its decision-support role, as called for by advocates of evidence-based conservation. Reintroduction research increasingly addresses a priori hypotheses, but remains largely focused on short-term population establishment. Similarly, studies that directly assist decisions by explicitly comparing alternative management actions remain a minority. A small set of case studies demonstrate full integration of research in the reintroduction decision process. We encourage the use of tools that embed research in decision-making, particularly the explicit consideration of multiple management alternatives because this is the crux of any management decisions.
Wind energy is considered a clean energy source, but produces negative impacts regarding avian mortality. The Barão de São João wind farm in Portugal's Sagres region is part of an important migratory flyway, crossed by 5000 individuals of 30 soaring bird species every autumn. The wind farm's licensing was conditioned to the implementation of rigorous mitigation procedures, namely a Radar Assisted Shutdown on Demand (RASOD) protocol to reduce the probability of bird casualties. A security perimeter with observers was aided by a radar system, detecting soaring birds approaching the wind farm. Turbines were to be turned-off when pre-defined criteria of intense migration or presence of threatened species were met. Turbine shutdown was operated by the wind farm staff after a request from the monitoring team (MT), or directly by the MT. Of the soaring birds crossing the wind farm, 55% were recorded at altitudes associated with high collision risk. However, due to RASOD, no soaring birds died from collisions during five consecutive autumns. The average annual shutdown period decreased continuously after the first year (105 h) reaching only 15 h when the MT was given direct access to shut down operations through SCADA (the remote system to monitor and control wind turbines). Shutdown period corresponded only to 0.2–1.2% of the equivalent hours in a year's wind farm activity. The use of radar, direct access to SCADA and cumulative experience by the MT improved the procedure's efficiency , allowing better judgments on the application of shutdown orders. Our results indicate that RASOD may be an essential tool in reconciling wind energy production with the conservation of soaring birds.
BIOGEOGRAPH/A — vol. X VII — 1993 (Pubb//‘Cato /7 31 otmbre 1994) ll popolamento animale e vegetale delI'Appennino Urnbro-Marchigiano Una avifauna dell’Appennino centrale nel ’500: il trattatello «Cognitione degl’uccelli et animali pertinenti al’aeregg e le lettere di Costanzo Felici da Piobbico ad Ulisse Aldrovancli MAS SIMO PANDOLFI (qq) & GIANNA ZANAZZO (qq“qq) (q‘) Irtzfuto dz' Sczienze Motfologic/9e - Unzberrzhi dz' Urkino - (q“q‘) Via G. Barri, 6 — Padowz. Key words: Historical fauna, XVI Century, Central Apennines, Birds. SUMMARY Original descriptions of 108 species of wild birds are reported from letters and a tractatus sent by Co- stanzo Felici, a 16th century Marchean doctor, to the Bologna natural historian Ulisse Aldrovandi. The letters were written during the period 1563-1573 at the specific request of Aldrovandi who \Vished to know the situation of the local avifauna. The mass of information refers above all to the mountains of the Pesaro hinterland and supplies a surprising amount of data both on this area of the Apennines and on the whole avifauna population of Italy. What are completely original are the data on nesting for a certain number of species now extinct in the Central Apennines, or indeed throughout Italy: Larnmergeier Gypaetuiq earbatur, Black Vulture Aegypi/ts momzc/Jztr, Griffon Vulture Gypr fizlvzzs, White Pelican Peleczmur anocrotalzzr, Raven Corvus carax and Rock Dove Colzmzbzz lz'w'a. A comparison of the situation whith that reported in Felici’s list shows that at least 15 species have become extinct in the Pesaro Apennine area and another 15 are certainly less common than they Vere in the 16th century. PREME S SA Tra i nurnerosi corrispondenti cli Ulisse Aldrovandi, il medico marchigiano Costanzo Felici(1) fu uno dei piu assidui ed ascoltati(2). La loro arnicizia, nata (1) Costanzo Felici nacque nel secondo decennio del ’500 a Casteldurante (l’attuale Urbania). Egli pero preferiva definirsi originario di Piobbico, nell’alto Pesarese, dove si erano trasferiti i suoi avi che avevano do- vuto abbandonare Lucca verso il 1330 in seguito alle discordie sorte tra Guelfi e Ghibellini. La sua famiglia annovero tra i propri rnembri letterati, rnatematici, giureconsulti, rnilitari e prelati. Felici studio at Perugia e a Padova clove il 31 agosto del 1552, consegui la laurea in arte e medicina, che gli consenti di esercitare la pro~ fessione di medico a Piobbico, a Sant’Angelo in Vado, a Pesaro, a e a Urbania. Al tempo stesso coltivo con notevoli risultati gli studi naturalistici e storici. Oltre che con Ulisse Aldrovandi, ebbe contatti con altri il- lustri scienziati, tra i quali Girolamo Cardano, l’Anguillara, Rigacci, Moderato ed altri. Mori a Pesaro il 5 feb- hraio 1585. (2) Che Felici fosse uno dei piu assidui e ascoltati collaboratori di Aldrovandi lo si deduce prendendo in esame le sue lettere e gli appunti che da queste traeva il destinatario (cf. il ms 136 della Biblioteca Universitaria di Bologna. Fondo Aldrovandi. t. H. c. 260v—263v).
Although senescence has been described for various fitness components in a wide range of animal species, few studies have studied senescence in long-lived species, and little is known about its interactions with environmental variation. Using a 32 year capture-mark-recapture dataset on the griffon vulture Gyps fulvus, we examined the demographic patterns of actuarial senescence and the patterns of year-to-year variation in survival rates. We found a significant, surprisingly late, decrease of annual survival probabilities from the age of 28 years onward and divided individual lifetimes into to three categories (juvenile, mid-age and senescent birds). In agreement with the environmental canalization hypothesis, our analyses uncovered 1) higher temporal variation of annual survival probabilities in both the juvenile and senescent age classes compared to the mid-age class and 2) low sensitivity of the population growth rate to the survival of both the juvenile and senescent age classes. Our results further suggested that the temporal variation in the survival of senescent birds might be related to intra-annual changes in air temperature amplitudes. Finally, using population dynamics modeling, we revealed contrasting effects of the inclusion of the senescent age class on predicted population growth, depending on how survival rates were modeled. Altogether, our results demonstrate the existence of a class of senescent birds that exhibit distinct demographic properties compared to juvenile and mid-age classes.This article is protected by copyright. All rights reserved.
Little is known of the life history of vultures. The reintroduction program of Griffon Vultures (Gyps fulvus fulvus) in the Causses (south of the Massif Central, France) and extensive monitoring by capture-mark-resighting of the released birds allowed us to obtain the first estimates of their survival. Adult survival rates are high (x̄ = 0.987 ± SE of 0.006). A release effect on adult survival was detected (only 0.743 ± 0.006 survival during the first year after release). Young born in the wild (less than three years old) had an annual survival rate of 0.858 ± 0.039. Mortality causes and erratic behavior of immature birds are considered in order to assess the effectiveness of this reintroduction program. Our results indicate that reintroductions of vultures and similar species should use adults that have bred in captivity within the target area rather than juveniles or immatures.
The estimation of survival distributions for animals which are radio-tagged is an important current problem for animal ecologists. Allowance must be made for censoring due to radio failure, radio loss, emigration from the study area and animals surviving p88l. :~the end of the study period. First we show that the Kaplan-Meier .procedure wid~ly used in medical and engineering studies can be applied to this problem. An example using some quail data is given for illustration. As radios maItunction -or are lost, new radio-tagged animals have to be added to the study. We show how this modification can easily be incorpor~.ted inf.<? the basic Kaplan-Meier procedure. Another example using quail data is used to illustrate the extension. We also show how the log rank test commonly used to compare two survival distributions can be generalized to allow for additions. Simple computer programs which can be run on a PC are available from the authors.
Two nonparametric estimators o f the survival distributionare discussed. The estimators were proposed by Kaplan and Meier (1958) and Breslow (1972) and are applicable when dealing with censored data. It is known that they are asymptotically unbiased and uniformly strongly consistent, and when properly normalized that they converge weakly to the same Gaussian process. In this paper, the properties of the estimators are carefully inspected in small or moderate samples. The Breslow estimator, a shrinkage version of the Kaplan-Meier, nearly always has the smaller mean square error (MSE) whenever the truesurvival probabilityis at least 0.20, but has considerably larger MSE than the Kaplan-Meier estimator when the survivalprobability is near zero.
Griffon Vultures Gyps fulvus are notoriously difficult to age precisely, given their delayed maturity and large inter-individual variation. However assessing the age of young individuals can be important for studies dealing with behaviour, population dynamics and conservation. Using a large sample of individually marked Griffon Vultures of known age in southern France, we studied changes with age of morphological parameters observable at distance on the ground. Combining features of bill colour, eye colour, shape and colour of neck ruff feathers and shape of upperwing greater coverts, it was possible to attribute age classes with a precision of c 2 years. The first characteristics to change were the colour of the bill, with the front of the bill getting clear before the sides of the bill, and the shape of the greater coverts, where pointed juvenile feathers were replaced by paler and more rounded feathers. In the second year, the ruff turned progressively paler and shorter to become adult-like in the seventh year for most individuals. The eye turned lighter only in the fifth year. Males tended to acquire adult plumages more rapidly than females.
Transhumance is a traditional livestock practice based on the movement of livestock between winter and summer pastures with importance placed on biodiversity conservation. We analyzed the transhumant activity of sheep and cows in the uplands of the Cantabrian Mountains, NW Spain, and its influence on the ecology and management of the griffon vulture, a scavenger with a relevant ecosystem function. For the first time, we provided strong evidence of the close relationship between vultures and transhumance, which was previously only suggested. Vultures occupied roosting sites very close to the summer pastures and often consumed livestock carcasses. There was a strong spatiotemporal adjustment in the use of these mountain areas by transhumant livestock, especially sheep, and vultures. The number of transhumant sheep and cows within 10–12.5 km around the roosts were the best predictors of vulture occurrence and abundance, respectively, in generalized linear mixed models. Our estimates of potentially available food from livestock carcasses for vultures indicated that our study area can maintain important griffon vulture populations through a system based on traditional livestock farming including transhumance. Thus, transhumance is able to influence the top of the ecosystem (scavengers) and could aid in sustainable management of griffon vulture populations. In our study area, transhumant sheep were reduced by 62% in the last 15 years and only 20% of summer pastures are now occupied. The potential impact that the ongoing loss of transhumant activity could have on mountain ecosystem conservation should be assessed and taken into account by the new European Common Agricultural Policy.
Intraspecific competitive behaviours were studied in a reintroduced population of Griffon Vultures Gyps fulvus in order to describe the pattern of competition between ages and sexes, assess the effect of reintroduction on competitive behaviour, and study the potential consequences of food management on competition. There was no evidence for a difference in feeding or display rates between age classes. However interaction rates, aggressiveness and dominance were higher in old adults than in the other age classes. No difference in the pattern of competition was found between sexes. There was no difference in the competitive ability (feeding rate and dominance) of reintroduced and wild-bred individuals. Feeding rates increased with resource availability. Group size also increased with food mass, but was lower than the theoretical maximum number of birds. This may be evidence of competition by interference where some individuals are able to increase their feeding rate by the exclusion of others. An increase in both the number of carcasses and the number of feeding sites is thus recommended to induce dispersal and reduce this competition.