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Browsing by Subject "species conservation"

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  • Nykänen, Roope (2023)
    Diets of wild owls have been studied by pellets, when the nutritional value of owl prey remains unclear. Fatty acids are an essential part of animal nutrition, acting as energy reserve, building blocks of membranes and precursors for signaling molecules. I studied whether Finnish owl species have species-specific characteristics in the fatty acid profiles of adipose tissue due to different diets and feeding habits. I also compared fatty acid profiles between wild and captive owls to elucidate if the diet of captive owls resembles the diet in the wild. Fatty acids from visceral adipose tissue and a liver were transesterified to fatty acid methyl esters, which were identified and quantified by gas-chromatographs linked to either a mass spectrometry or flame ionisation detector. The fatty acid compositions were compared with Principal Component Analysis and statistical significance of the separations between species, origins and tissues were studied by Soft Independent Modelling of Class Analogies. Differences in the relative concentrations of individual fatty acids and their structural category sums were evaluated by the Kruskal-Wallis test followed by the Wilcoxon rank-sum test. Compared to wild owls, captive owl (snowy owl Bubo scandiacus and Eurasian eagle-owl Bubo bubo) adipose tissues had lower relative concentrations of many long-chain polyunsaturated fatty acids (PUFAs), such as arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid. The captive owls also had lower n-3 PUFA/n-6 PUFA ratio than the wild owls. I suggest that these differences arise from anthropogenic food given to the prey of the captive owls. In the future, the feeding and breeding of captive owls could be improved and potential health hazards prevented by giving the owls a diet rich in long-chain PUFAs, either by giving the prey more versatile diet or adding supplements to the owl’s diet. The adipose tissues of wild Eurasian eagle-owls contained higher total relative concentrations of monounsaturated fatty acids than the species belonging to the Strix genus. On the other hand, long-chain PUFAs were more prominent in the Strix owls. I suggest that these differences in the fatty acid composition are due to the disparities in feeding behaviour: the Eurasian eagle-owls eat carrions and large prey that cannot be swallowed whole, which may lead to consuming more the body outer parts of the prey. The fatty acid composition of the eagle-owls can also be affected by urban prey that have consumed anthropogenic food. In the future, the fatty acid composition of wild prey should be examined to be able to evaluate the prey composition of owls and its effect on the owl fatty acid profile with physiological consequences, the knowledge that could be used in the future decision-making that supports the conservation of owls.