Simulated warm and cold fronts impact migratory behaviour and corticosterone levels in White-throated Sparrows (Zonotrichia albicollis)
Description
We investigated the possible interaction between weather cues, migratory behaviour, and corticosterone levels by testing the effect of experimental changes in temperature and barometric pressure on White-throated Sparrows’, Zonotrichia albicollis, nocturnal migratory and diurnal behaviour, and corticosterone levels during a spring migration. We hypothesized that the sparrows would alter migratory restlessness and corticosterone levels in response to simulated weather cues. Using a hypobaric climatic wind tunnel, we exposed sparrows to simulated low-pressure warm fronts or high-pressure cold fronts. We recorded behaviour during the weather manipulation and following lights out, and collected fecal samples the next morning. The recordings were scored using BORIS, with diurnal activity including movement, drinking, and eating behaviours. The nocturnal activity included migratory restlessness behaviour. Corticosterone levels were measured through an ELISA kit hormone assay. The data were analyzed using RStudio software; we ran linear mixed models to compare behaviours and corticosterone levels across the different treatment groups. We also ran a repeated-measures correlation to see the relationship between migratory restlessness and corticosterone regardless of treatment group. During the weather manipulations, sparrows showed reduced movement in the experimental conditions as lights out was approaching, and they ate more in the cold front treatment. Following lights off, sparrows showed an increase in migratory restlessness in both experimental conditions compared to no change in weather cues, with the most restlessness occurring 1.5 hours after lights went out. Fecal corticosterone levels were highest following the cold front treatment. Furthermore, the degree of migratory restlessness per night and corticosterone levels were positively correlated. These experimental results demonstrate that White-throated Sparrows adjust their migratory behaviour and experience endocrine regulation in response to changes in temperature and barometric pressure.
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Institutions
- Western UniversityOntario, London