Bonellis Eagle Study And Conservation Group

Murcia, Spain

Bonellis Eagle Study And Conservation Group

Murcia, Spain

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Zuberogoitia I.,Icarus | Zabala J.,University of the Basque Country | Martinez J.E.,Bonellis Eagle Study and Conservation Group | Gonzalez-Oreja J.A.,Seccion de Vertebrados | Lopez-Lopez P.,University of Alicante
Animal Conservation | Year: 2014

A consistent body of literature suggests that migratory species, ecological specialists and/or populations living on the borders of their distribution ranges are expected to be among the most seriously affected by alterations in environmental conditions. In this framework, we tested the combined effects of human disturbance and weather conditions on the breeding performance of a long-lived endangered scavenger, the Egyptian vulture, in a study area (Biscay, northern Spain) located close to the edge of its worldwide range. Furthermore, we tested the effect of specific management strategies aimed at preventing the impact of human disturbance on the species' breeding output. Our results showed that the breeding success was negatively correlated with weather conditions, mainly rainfall and number of rainy days in June, that is the rearing period of small nestlings. Importantly, human disturbance was the main factor affecting Egyptian vultures' productivity. In fact, during the study period (2000-2012), we detected cases of high-level disturbance in 59 nests (30.9%) within 17 of the 22 monitored territories, which only produced three fledglings overall. In 2010, we started the application of management actions for preventing human disturbance, first in a few control territories and later, in 2011 and 2012, across the whole study area. The measures were found to be successful, as the breeding success increased to levels similar to those previously detected in non-disturbed nests. Our results showed that management strategies aimed at preventing human disturbance are of paramount importance in order to assure the conservation of this endangered species. Animal Conservation © 2014 The Zoological Society of London.


Zuberogoitia I.,Icarus | Martinez J.E.,Bonellis Eagle Study and Conservation Group | Margalida A.,Bearded Vulture Study and Protection Group | Gomez I.,Sociedad para el Estudio de las Ayes Rapaces SEAR | And 2 more authors.
Ornis Fennica | Year: 2010

In natural conditions, Griffon Vultures typically show shy behaviour and escape by flying if approached by humans. According to the state-dependent foraging theory, Griffon Vultures should modify their foraging behaviour depending on food availability and predation risk, humans being the main potential predator. We tested the Reaction Time (RT) and Flight Initiation Distance (FID) in five different artificial feeding schemes over three years in which food availability in the field varied significantly. The first scenario was set in a so-called "vulture restaurant", in which government employees feed vultures that may exhibit tame behaviour and stay within a few meters from a feeding person. Scenario 2 involved similar conditions, but here the researchers not employees placed the food in the vulture restaurant. The vultures did not land at the restaurant until one day had passed, and they flew away when people approached them within 250 m. The third scenario was established in a local zoo several months after the closure of the vulture restaurant. Here, employees fed captive vultures that were often accompanied by wild birds that landed to take food. The RT was 14.2 min and the FID was 50 m. The fourth scenario was established during the subsequent breeding season in a mountain where vultures were fed by the authors of the present study. The RT was 2.8 min and the FID was 15.2 m. The fifth scenario was established in another mountain after the breeding season. Now, the RT was 19.2 min and the FID was 52.2 m. These results demonstrate the ability of vultures to evaluate the predation risk depending on food availability and their state of hunger, and their ability to modify their behaviour from "natural" caution ("shyness") towards a more tolerant ("fearless") behaviour.


Zuberogoitia I.,Icarus | Zabala J.,Arrigorriaga | Martinez J.E.,Bonellis Eagle Study and Conservation Group | Olsen J.,University of Canberra
Journal of Zoology | Year: 2015

All animals face the decision of where to breed, a decision that exerts a strong impact on fitness. We examined changes in choice of nest site in peregrine falcons (Falco peregrinus) over a 17-year period in northern Spain. Falcons had a mean of 3.1 eyries per territory, each location used for a mean of 3.0 consecutive years. Surprisingly, change in eyrie location was not predicted by breeding productivity. However, breeding success decreased with the number of consecutive years that eyries were reused. Ectoparasitic infestation was not a significant predictor in the models. The number of fledglings in the previous season was the main factor explaining the eyrie-switching decision, with successful pairs being more prone to move. Newly established females showed a higher tendency to switch (59%) than older territorial females (38%) but males did not exhibit the same tendency. High rainfall in April had a negative effect on productivity. In the case of females, changing the eyrie from one season to the next had a positive effect on productivity. In the case of models run with males as a random factor, rainfall in April and eyrie shelter reached significance. So, contrary to the 'win-stay, lose-switch' rule and in direct contrast with general literature, peregrines changed eyries after successfully raising large broods and eyrie switching increased the breeding success of females but not of males. © 2015 The Zoological Society of London.


Martinez J.E.,Bonellis Eagle Study and Conservation Group | Calvo J.F.,University of Murcia | Jimenez-Franco M.V.,University of Murcia | Zuberogoitia I.,Icarus | Lopez-Lopez P.,University of Valencia
Ornis Fennica | Year: 2016

Mechanisms regulating colour polymorphism remain largely unknown and detailed investigation is required to explore the biological consequences on population dynamics. This paper presents the first study of the possible connection between colour polymorphism and productivity in a Booted Eagle (Aquila pennata) population breeding in southeastern Spain. To that end we used 19 years of data of non-marked individuals. A total of 738 pale (91.6%) and 68 dark (8.4%) adult Booted Eagles were observed in our study area, including 57 territories. Our results suggest that colour morph of both sexes remained stable in the population over the study period. Although we found a higher number of offspring produced by parents exhibiting the dark morph than those of the pale morph, statistical differences were not significant. Hence, our models showed that colour polymorphism was not a good predictor of Booted Eagles' productivity, although further research by capture-recapture analysis would be needed to explore the influence of colour variation on fitness components at individual level and its consequences at population level of long-lived species.


Zuberogoitia I.,Icarus | Martinez J.E.,Bonellis Eagle Study and Conservation Group | Martinez J.E.,University of Murcia | Gonzalez-Oreja J.A.,Seccion de Vertebrados | And 2 more authors.
Journal of Ornithology | Year: 2013

In raptors, brood size seems to be closely related to the size of prey brought to the nest, the delivery rate and the degree of parental effort. In the case of Peregrine Falcons (Falco peregrinus), any increase in the size of prey is considered to be linked to the increased role of the female in hunting. We investigated the possible effects of differences between sexes in prey composition on the brood size of a Peregrine Falcon population in northern Spain during 1998-2010. The study area was located on the Gulf of Biscay, in the middle of the Western European Flyway, hence a wide range of prey species were available during the breeding season. We monitored a total of 320 Peregrine nests, which produced 603 fledglings (average brood size = 2. 67) and identified 2,832 prey, from 128 different bird species. Our results indicate that brood size was negatively related to bad weather (e. g. rainfall in April), but not with the body mass of the prey species delivered to the nest. There were no significant differences in body mass between attacked versus captured prey, nor was mass affected by the sex of the attacking Peregrine, and gender had no significant effect on the probability of a successful capture. Therefore, males and females hunted prey species of similar body size. Our data suggest that prey size is not related to the number of fledglings, although this may play an important role; Peregrines can compensate by hunting for more or larger prey. © 2012 Dt. Ornithologen-Gesellschaft e.V.


Zuberogoitia I.,Icarus | Gonzalez-Oreja J.A.,Seccion de Vertebrados | Martinez J.E.,Bonellis Eagle Study and Conservation Group | Zabala J.,Sebero Otxoa | And 2 more authors.
European Journal of Wildlife Research | Year: 2013

The outbreak of bovine spongiform encephalopathy provoked restrictive European sanitary legislation that forced farmers to remove livestock carcasses from the wild. This had serious repercussions for the scavenger raptor guild. Against this background, we developed a study to analyse the foraging movements of Eurasian griffon vultures (Gyps fulvus) in northern Spain. We ringed 241 griffon vultures with alphanumeric plastic rings in Biscay between 2000 and 2011 and set experimental feeding stations in 24 sites over an area of 10,614 km2; recording re-sightings of the ringed vultures between 2005 and 2012. Using these re-sighting records, we tested whether birds randomly moved long distances whilst searching for food, or if vulture re-sightings were restricted to a few feeding sites within a limited area. We summarised 329 field-work days, with an average of 2.06 ringed vultures re-sighted per day, accounting for 1,017 re-sightings. Adult vultures were detected in three separate foraging nuclei within the study area. Movements out of the main foraging nuclei were statistically less frequent than would be expected if adult vultures accessed all resources at a similar rate. Once established at breeding areas, subadult vultures behaved in the same way as adults. Our results suggest that vultures' home ranges are largely restricted to zones close to breeding areas. This has important consequences from a conservation point of view, suggesting that management decisions should take into consideration spatial scale effects. © 2012 Springer-Verlag Berlin Heidelberg.


Martinez J.E.,University of Murcia | Martinez J.E.,Bonellis Eagle Study And Conservation Group | Zuberogoitia I.,Icarus | Jimenez-Franco M.V.,University of Murcia | And 2 more authors.
European Journal of Wildlife Research | Year: 2016

Analysis of the 949 and 434 cases of mortality of Booted Eagle Aquila pennata and Short-toed Snake Eagle Circaetus gallicus, respectively, recorded by wildlife rehabilitation centres in Spain over a 16-year period (1990–2006) shows that power lines (19.5 and 35.2 %, respectively) and killing (32.5 and 22.9 %, respectively) were the main known causes of death. Multinomial regression models were used to analyse geographical and temporal variations in the causes of death. For the Booted Eagle, both factors (zone and year) were statistically significant, while there were only significant temporal variations for the Short-toed Snake Eagle. In the Booted Eagle, killing occurred more frequently than expected in the east and north of the country compared to the other Spanish regions. Power line casualties were significantly more frequent in the southern and eastern regions, and less common in the north. In both species, the multinomial models indicate that while the number of cases of killing significantly decreased during the 16 years studied, power line casualties increased. Our study suggests that human-induced mortality continues to be the main factor contributing to mortality for Spanish Booted Eagles and Short-toed Snake Eagles. Since a reduction in the mortality caused by human activities is a priority in the conservation strategies for raptor species, management guidelines are discussed. © 2015, Springer-Verlag Berlin Heidelberg.


Martinez J.E.,University of Murcia | Martinez J.E.,Bonellis Eagle Study and Conservation Group | Jimenez-Franco M.V.,University of Murcia | Zuberogoitia I.,Icarus | And 2 more authors.
Acta Oecologica | Year: 2013

Different species show different responses to natural disturbances, depending on their capacity to exploit the altered environment and occupy new niches. In the case of semi-arid Mediterranean areas, there is no information available on the response of bird communities to disturbance caused by extreme weather events. Here, we evaluate the short-term effects of a heavy snowfall and strong winds on three long-lived species of forest-dwelling raptor in a semi-arid Mediterranean region situated in the south-east of Spain. The loss of nests was significantly higher in the first and second years following the disturbance than in the third year. The three species studied exhibited great tolerance to the short-term effects of the storm since we found no differences in density or reproductive parameters between the nine breeding seasons prior to the disturbance and the three which immediately followed it. We suggest that the tolerance shown by these three species to windstorms in semi-arid Mediterranean zones could be an adaptive response, resulting from the climatic and human pressures which have prevailed from the Bronze Age to the present day. © 2013 .


Jimenez-Franco M.V.,University of Murcia | Martinez J.E.,University of Murcia | Martinez J.E.,Bonellis Eagle Study and Conservation Group | Calvo J.F.,University of Murcia
Journal of Zoology | Year: 2014

The presence of old nest structures can be an influential resource in reuse patterns and reproductive output for some birds. We used 15-year territorial occupancy data referring to the booted eagle Aquila pennata (a trans-Saharan migrant) and the common buzzard Buteo buteo (a sedentary species in southeastern Spain) to analyse old nest effects in territorial settlement patterns (new territories, new establishments in old territories and reoccupancies), to describe the patterns of nest building versus nest reuse and to test whether nest building is costly in terms of current reproductive output. The results indicated that the rates of reoccupancy and new establishments in old territories were higher than the rates of creating new territories for both booted eagles (74.13, 23.35 and 2.52%, respectively) and common buzzards (58.25, 38.84 and 2.91%, respectively). When breeding pairs settled in old territories, we observed a noticeably lower pattern of nest building than nest reuse both in booted eagles (10.03 vs. 89.97%) and common buzzards (8.00 vs. 92.00%). The nest-building rate by booted eagles was significantly lower in reoccupancies than in new establishments in old territories. Reproductive output for each species was not increased by nest reuse, although breeding success and productivity were significantly higher when newly established booted eagles constructed new nests than when reusing old nests. Our findings provides an interesting view on how forest raptors use old nests as important resources, probably taking them as location cues for nesting site selection and suggesting that unused nest sites should be left undisturbed since they could attract breeding raptor pairs in future years. © 2013 The Zoological Society of London.


Jimenez-Franco M.V.,University of Murcia | Martinez J.E.,University of Murcia | Martinez J.E.,Bonellis Eagle Study and Conservation Group | Calvo J.F.,University of Murcia
PLoS ONE | Year: 2014

Structural elements for breeding such as nests are key resources for the conservation of bird populations. This is especially true when structural elements require a specific and restricted habitat, or if the construction of nests is costly in time and energy. The availability of nesting-platforms is influenced by nest creation and persistence. In a Mediterranean forest in southeastern Spain, nesting-platforms are the only structural element for three forest-dwelling raptor species: booted eagle Aquila pennata , common buzzard Buteo buteo and northern goshawk Accipiter gentilis. From 1998 to 2013, we tracked the fate of 157 nesting-platforms built and reused by these species with the aim of determining the rates of creation and destruction of nesting-platforms, estimating nest persistence by applying two survival analyses, describing the pattern of nest reuse and testing the effects of nest use on breeding success. Nest creation and destruction rates were low (0.14 and 0.05, respectively). Using Kaplan Meier survival estimates and Cox proportional-hazards regression models we found that median nest longevity was 12 years and that this was not significantly affected by nest characteristics, nest-tree dimensions, nest-builder species, or frequency of use of the platform. We also estimated a transition matrix, considering the different stages of nest occupation (vacant or occupied by one of the focal species), to obtain the fundamental matrix and the average life expectancies of nests, which varied from 17.9 to 19.7 years. Eighty six percent of nests were used in at least one breeding attempt, 67.5% were reused and 17.8% were successively occupied by at least two of the study species. The frequency of nest use had no significant effects on the breeding success of any species. We conclude that nesting-platforms constitute an important resource for forest raptors and that their longevity is sufficiently high to allow their reuse in multiple breeding attempts. © 2014 Jiménez-Franco et al.

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