Hernandez, N., Genovart, M., Igual, J.-M. and Oro, D., 2015 The influence of environmental conditions on the age pattern in breeding performance in a transequatorial migratory seabird. Forntiers in Ecology and Evolution.http://dx.doi.org/10.3389/fevo.2015.00069
Abstract: Several studies of marine top predators, above all of seabirds, have
analyzed the effects of either individual age or environmental
fluctuations on reproduction; nevertheless, little is known about the
age patterns in breeding performance in a variable environment.
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Photo: Pedro Trejo (c) |
To
investigate the simultaneous influence of age and environmental
conditions on laying dates and egg volumes, we tested different climate
and food availability indices in a transequatorial migratory seabird
using female data from a 23-year study. Our results show an improvement
in breeding parameters with age (i.e., earlier laying dates and greater
egg volumes) but no pattern of senescence in older age groups. The best
models showed an interaction of time and age in breeding performance,
i.e., the age pattern of breeding performance changed each year likely
as a result of environmental variability.
Nevertheless, climatic indexes
used here explained part of that annual variability: NAO and SOI index
accounted for 24 and 20% of deviances in laying dates and egg volume,
respectively. Part of that unexplained variability might be related to
other processes such as intermittent breeding and the individual quality
of breeders, which were not assessed in our study.