title: The influence of diet on nestling body condition of an apex predator: a multi-biomarker approach.
abstract: Animal body condition refers to the health and physiological state of individuals, and multiple parameters have been proposed to quantify this key concept. Food intake is one of the main determinants of individual body condition and much debate has been generated on how diet relates to body condition. We investigated this relationship in free-living Bonelli's eagle (Aquila fasciata) nestlings sampled at two geographically distant populations in Spain. Nestlings' main prey consumption was estimated by isotopic analyses. A multi-biomarker approach, including morphometric and blood biochemical measures (i.e. hematocrit, plasma biochemistry and oxidative stress biomarkers), enabled us to integrate all the body condition measures taken. A greater consumption of a preferred prey [i.e. the European rabbit (Oryctolagus cuniculus)] improved nestling body condition, as indicated by lower levels of cholesterol in plasma, greater activity of enzymes mediating in protein catabolism, higher levels of tocopherol and glutathione, and less glutathione peroxidase activity, which also suggested lower degree of oxidative stress. On the other hand, increased diet diversity was positively correlated with higher levels of oxidized glutathione, which suggests that these nestlings had poorer body condition than those with a higher frequency of preferred prey consumption. Several factors other than diet [i.e. altitude of nesting areas, nestling sex and age, sampling time (before or after midday) and recent food ingestion] had an effect on certain body condition measures. Our study reveals a measurable effect of diet on a predator's body condition and demonstrates the importance of considering the potential influence of multiple intrinsic and extrinsic factors when assessing animal body condition.
authors: Equip de Biologia de la Conservació, Departament de Biologia Animal, Universitat de Barcelona, Av. Diagonal 643, 08028, Catalonia, Barcelona, Spain. jresano@ub.edu.|Division of Conservation Biology, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012, Bern, Switzerland. jresano@ub.edu.
authors: Jaime
authors: J
authors: Resano-Mayor
authors: Equip de Biologia de la Conservació, Departament de Biologia Animal, Universitat de Barcelona, Av. Diagonal 643, 08028, Catalonia, Barcelona, Spain.
authors: Antonio
authors: A
authors: Hernández-Matías
authors: Equip de Biologia de la Conservació, Departament de Biologia Animal, Universitat de Barcelona, Av. Diagonal 643, 08028, Catalonia, Barcelona, Spain.
authors: Joan
authors: J
authors: Real
authors: Equip de Biologia de la Conservació, Departament de Biologia Animal, Universitat de Barcelona, Av. Diagonal 643, 08028, Catalonia, Barcelona, Spain.
authors: Francesc
authors: F
authors: Parés
authors: Departamento de Biología Aplicada, Univeridad Miguel Hernández, Ctra. Beniel km 3.2, 03312, Orihuela, Alicante, Spain.|Departamento de Biología de la Conservación, Estación Biológica de Doñana-CSIC, C/Américo Vespucio, s/n, 41092, Seville, Spain.
authors: Marcos
authors: M
authors: Moleón
authors: Instituto de Investigación en Recursos Cinegéticos (IREC) CSIC-UCLM-JCCM, Rda Toledo s/n, 13071, Ciudad Real, Spain.
authors: Rafael
authors: R
authors: Mateo
authors: Instituto de Investigación en Recursos Cinegéticos (IREC) CSIC-UCLM-JCCM, Rda Toledo s/n, 13071, Ciudad Real, Spain.|Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, 76829, Landau, Germany.
authors: Manuel E
authors: ME
authors: Ortiz-Santaliestra
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000975:Antioxidants / Q000032:analysis; D015415:Biomarkers / Q000097:blood*; D001774:Blood Chemical Analysis / Q000592:standards; D001835:Body Weight; D020307:Eagles / Q000502:physiology*; D004912:Erythrocytes; D005247:Feeding Behavior; D005260:Female; D006400:Hematocrit; D008297:Male; D018384:Oxidative Stress; D011235:Predatory Behavior / Q000502:physiology; D011817:Rabbits; D012016:Reference Values; D013030:Spain
chemical_list: D000975:Antioxidants; D015415:Biomarkers
keywords: Blood biochemistry; Body condition; Optimal foraging theory; Oxidative stress; Raptors; Stable isotope analysis