Browsing by Subject "Raptor"

Now showing 1 - 2 of 2
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    Eurasian eagle owls Bubo Bubo adjust nest food stores to nestling age
    (BioOne Digital Library, ) Puche Gómez, Sara; Perales Pacheco, Pablo; Botella, Francisco; Sánchez-Zapata, José Antonio; Pérez-García, Juan Manuel; Gómez Ramírez, Pilar; Ciencias Sociosanitarias
    Some bird species, particularly owls, store prey within their nests during the breeding season. Food storage has been explained by the need to buffer the environmental variability of resources available for the offspring. This study describes food stores of the Eurasian Eagle Owl Bubo bubo in the southeast of the Iberian Peninsula and evaluates which intrinsic and extrinsic factors influence their presence and composition. Between 2003 and 2021, we studied the presence, abundance, biomass and species richness of prey in food stores found in 318 nests. Stores occurred in 63.5% of nests and included 520 prey items belonging to 23 different species. The main prey species was the European Rabbit oryctolagus cuniculus (71.43%). The greatest abundance of prey and biomass found in the stores occurred when the owlets were between 20 and 25 days old, that is when peak owlet growth occurs. Neither abundance nor biomass of prey in stores were related to brood size. Similarly, the frequency of food store occurrence in nests per year was unrelated to precipitation in the preceding months, which serves as a proxy of rabbit abundance. Globally these results support the hypothesis of that Eagle Owl parents adjust the stores according to when their owlets have their highest energy demands, irrespective of brood size and likely prey abundance. Food storage may help Eagle Owls to maximise their reproductive success in a semi-arid environment subject to high environmental variability.
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    Temporal trends of inorganic elements in a common kestrel (Falco tinnunculus) population from south west Spain
    (Elsevier, 2021-01-18) Manzano, Javier; Mendez-Fernández, Paula; Gil-Jiménez, Esperanza; Romero, Diego; Ferrer, Miguel; Ciencias Sociosanitarias
    Historical variations (1966e2016) in the exposure to inorganic elements in raptors of South West Spain have been little studied. Therefore, uncertainty exists concerning whether environmental or anthropo genic inputs, as well as dietary strategy shift, may cause changes in exposure patterns. To address this gap, essential and non-essential inorganic elements were measured in Common kestrel (Falco tinnun culus) feathers from museum specimens and free-living individuals spanning a 50-year period. Moreover, stable isotopes of d13C and d15N were also measured as proxies of Common kestrel feeding ecology over time. In general, all elements showed significant increasing trends overtime, suggesting changes of in puts from local sources. Moreover, d15N signatures were correlated to the variations in Al, Cr, Cu, Fe, K, Li, Mg, Mn, Ni, P, Pb, Rb, Sr, Ti, V and Zn concentrations, suggesting trophic changes in this kestrel popu lation as well as possible biomagnification processes. Finally, some values of Cr, Mn and Pb were above the threshold concentrations of potential toxicity.