2 research outputs found
The influence of diet on nestling body condition of an apex predator: a multi‑biomarker approach
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
The influence of diet on nestling body condition of an apex predator: a multi-biomarker approach
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.This study was funded by projects CGL2007-64805 and CGL2010-17056 from the “Ministerio de Ciencia e Innovación, Gobierno de España”, the “Àrea d’Espais Naturals de la Diputació de Barcelona” and Miquel Torres S.A. J. Resano-Mayor was supported by a predoctoral grant from the “Departamento de Educación, Gobierno de
Navarra; Plan de Formación y de I+D 2008–2009”.Peer Reviewe