Arrival date and territorial behavior are associated with corticosterone metabolite levels in a migratory bird

Abstract

Glucocorticoids promote the mobilization of energy stores and they may facilitate the expression of energetically expensive functions. Early arrival on the breeding grounds in migratory species and territorial competition are energetically demanding activities that may be supported by elevated baseline glucocorticoid levels. Here, we evaluated the associations between the baseline levels of excreted corticosterone (CORT) metabolites of male Pied Flycatchers (Ficedula hypoleuca) just after arriving on their breeding area and timing of arrival, considering ornamental traits indicative of social status, like forehead patch size and black plumage coloration, as well as heat shock protein levels (HSP60). We observed a positive association of CORT metabolites with HSP60 levels, which are synthesized under several environmental challenges affecting cell homeostasis. Our data showed a negative association between arrival date and CORT metabolite levels, possibly as a result of the higher energetic demands imposed by the hard environmental conditions experienced at the time of an early arrival after migration. We observed a negative relationship of forehead patch dimensions and CORT metabolite levels, suggesting that dominance is associated with low baseline CORT metabolites. Also, males that expressed a higher degree of territorial behaviour when exposed to a playback song of a conspecific at their nest-box showed higher CORT metabolites upon arrival than males that expressed a lower degree of territorial behavior. This may indicate that elevated baseline CORT metabolite levels may facilitate an intense territorial competition in males. Thus, male-male competition may be a factor affecting observed baseline glucocorticoid levels in migratory birds.

Multistate Mark–Recapture Analysis Reveals No Effect of Blood Sampling on Survival and Recapture of Eastern Kingbirds (Tyrannus tyrannus)

“…WITH THE RELATIVE ease and aífordability of modern labora-behavioral studies (Dolan et al 2007, Baienger et al 2009); to meatory techniques, increasing numbers of field biologists regularly col-sure metabolites (Lyons et al 2008, Lobato et al 2010, hormones lect blood samples from their study organisms to extract DNA for (Spinney et al 2006, Van Hout et al 2010, or stable isotopes The Auk, Vol. 128, Number 3, pages 514-521.…”

Territorial resource valuation deviates from habitat quality in an ecologically trapped, long-distance migratory bird

“…According to the "Challenge Hypothesis", males are able to increase testosterone levels relative to the territorial challenge to facilitate aggressive behavior during the breeding season (Wingfield et al 1990). For instance, Lobato et al (2010) recently found that early-arriving male Pied flycatchers (Ficedula hypoleuca) displayed stronger territoriality and had higher corticosterone metabolite levels compared to late-arriving males. However, the aggressive behavior of males is not always associated with high testosterone levels, and the reasons for this are still under debate (reviewed by Goymann 2009).…”

Phenotypic plasticity in breeding plumage signals in both sexes of a migratory bird: responses to breeding conditions

“…This evidence accords well with the hypothesis of costs which predicts patch decrements after higher levels of breeding exertion (Gustafsson et al ). Early breeding males are probably those suffering higher reproductive costs due to the costs of migrating early (Ruiz‐de‐Castañeda et al ) and the stiffer competition for nest cavities at the beginning of the breeding season (Lobato et al ). According to the cost hypothesis, we should expect these males to show patch decreases compared with late breeders as found for forehead patches.…”

“…UV reflectance of white patches has been analyzed in other studies of the species (Lehtonen et al , Sirkiä and Laaksonen ). In this study we focus on the area of these plumage patches as in other studies of the species (Galván and Moreno , Lehtonen et al , Lobato et al , Moreno et al , , , Cantarero et al , , Laaksonen et al , Sirkiä et al , Plaza et al ). Moreover, we have previously shown that area and UV reflectance of wing patches are positively correlated, at least in females (Cantarero et al ).…”