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Zuberogoitia I.,Icarus | 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.

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.

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.

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 .

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