Kleptoparasitism is a well-known foraging strategy used by many colonial seabirds. The expression of this behavior can reduce the cost of foraging during the breeding season and ultimately this can be reflected in physiological parameters. Here we analyzed the relationship between the trophic strategy of Common Terns Sterna hirundo and two hormones, that are known to be involved in decision-making during the reproductive cycle and foraging activities: corticosterone (CORT) and prolactin (PRL). The study was conducted during the breeding seasons 2012–2014 at the Banter See colony in northern Germany where individuals with different foraging strategies were identified and monitored since 2008. We studied the concentration of hormones in two groups of birds: kleptoparasitic individuals i.e. individuals who steal the food captured by another individual, and honest individuals i.e. individuals who obtain the food on their own. Blood samples were obtained during the mid-incubation period using a non-invasive technique. Both hormones showed no significant relationship to each other. CORT concentration was similar in both groups of birds. However, the concentration of PRL was higher in parasitic than honest individuals in 2014. In addition, CORT modelling indicated a year effect (higher CORT in 2013), and PRL modelling indicated a significant effect of year (higher PRL in 2012) and a significant interaction between year and the trophic strategy in 2014. The results show no clear relationship between the feeding strategy and studied corticosterone and prolactin levels.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 52 • No. 2