Biology subjects

Sepp, T.

Publications and source records attributed to Sepp, T..

3 recordsLinked to original sources

bioRxiv2025

Consistent among-individual variations in nest defence behaviour in a colonial seabird are associated with nesting site selection

Behavioural responses are among the fastest ways for wild animals to respond and adapt to environmental change. In breeding birds, nest defence behaviour is particularly important, as it directly influences reproductive success. However, the variability of this behaviour, and its links to environmental conditions and fitness, remain poorly understood. Here, we investigate the repeatability of flight initiation distance (FID) - a proxy for nest defence behaviour - in Common gull (Larus canus) breeding pairs within a seabird colony. We assess how consistent differences in FID between gull pairs relate to nest-site characteristics and fitness-related traits. We find that FID is strongly repeatable at the pair level (R = 0.50), indicating consistent behavioural differences among breeding pairs. Moreover, pairs with shorter FID nest at higher elevations and in areas with higher conspecific density compared to pairs with longer FID. Finally, our results show that these different behavioural responses, linked to different nest-site contexts, do not lead to clear differences in terms of fitness outcomes, suggesting that breeding pairs with marked behavioural differences could achieve similar fitness by matching the environmental conditions of their nesting site with their behavioural responses to perceived risks.

evolutionary biology↗

bioRxiv2023

Salivary corticosterone reflects plasmatic levels in a wild seabird.

Wild animals have been increasingly exposed to a wide range of stressors, mainly due to the intensification of human activities and habitat modifications. Consequently, new tools in order to assess the physiological and health status of wild animals have been developed. In particular, glucocorticoids have received a special attention. Primarily metabolic hormones, they are also used to evaluate the stress level of organisms. While historically measured in blood samples, new less-invasive methods have been recently developed to measure glucocorticoids in matrices such as faeces, hairs/feathers, or saliva. To date, measurements in saliva are still in their infancy despite the numerous advantages of the matrix: non-invasive, reflects the biologically active portion of glucocorticoids, allows to measure both baseline and stress-induced levels. In addition, most studies using saliva have been performed on domestic and captive animals, and recent development in wild animals have focused on mammals. Here, we show, for the first time that saliva could also be reliably used in free-ranging birds, as glucocorticoid levels in saliva strongly correlated with plasma levels. This promising result opens new avenues for a non-invasive sampling method to assess health status of wild birds in conservation biology and ecology.

ecology↗

bioRxiv2021

Antibiotic treatment increases yellowness of carotenoid feather coloration in greenfinches (Chloris chloris)

Carotenoid plumage coloration is an important signal of quality, and plays an important role in mate choice in many bird species. However, it remains unclear what mechanism makes carotenoids an honest signal. Here, we test the hypothesis that carotenoid plumage coloration might indicate gut health. Parasitic and microbial infections can affect nutrient absorption due to decreased gut surface or by altered gut microbiome. We took an advantage of a naturally occurring coinfection of parasites inhabiting the upper and lower portions of the digestive track to distinguish between the direct and indirect effects of parasites on carotenoid acquisition. Protozoan coccidian intestinal parasites are widespread in greenfinches (Chloris chloris) and the majority of greenfinches are infected in nature. Trichomonosis is an emerging disease of the upper digestive track that causes high mortality among greenfinches. We captured wild greenfinches (N=71) and administered anticoccidial medication toltrazuril (TOLTRA) to one group, antibiotic metronidazole (METRO) that is also effective for treating Trichomonas gallinea, to the second group, and third group received no medication. In the METRO group, feathers grown during the experiment had significantly higher chroma of yellow parts, but there was no effect of TOLTRA on feather chroma. These results suggest that METRO increased the efficiency of carotenoid modification or deposition to the feathers rather than nutrient acquisition, and/or freed energy resources that could be invested in coloration. Alternatively, in accordance with shared pathway hypothesis, increase in efficiency of vital cellular processes might have occurred, as many microbial metabolites can modulate mitochondrial and immune function.

ecology↗