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414 results on '"Pravosudov, Vladimir V."'

21. Feather growth rate and hormone deposition vary with elevation but not reproductive costs in resident Mountain Chickadees.

Author

Sonnenberg, Benjamin R, Branch, Carrie L, Pitera, Angela M, Benedict, Lauren M, Heinen, Virginia K, Ouyang, Jenny Q, and Pravosudov, Vladimir V

Subjects
MOUNTAIN chickadee, FEATHER growth, BIRD hormones, BIRD reproduction, CORTICOSTERONE
Abstract

Many organisms engage in metabolic tradeoffs to manage costs associated with reproductive output which often leads to these costs carrying over into the future. Compensatory mechanisms vary across life history strategies and are expected to result in near-optimal fitness gains for the investor. Here we investigated whether environmental differences associated with increasing montane elevation and variation in reproductive output of a resident passerine songbird, the Mountain Chickadee (Poecile gambeli), were related to physiological conditions during annual molt. Higher elevations are associated with harsher environmental conditions during the winter, which results in later and shorter breeding seasons than at lower elevations. We sampled the outermost tail feathers from adult birds in the fall after their prebasic molt, which initiates closely after reproduction (e.g. after parental care has ceased, ~1–3 weeks). We measured the hormone corticosterone deposited in feathers (fCORT) and feather growth rates for evidence of physiological effort predicted to be driven by several units of reproductive output (e.g. breeding timing, clutch and brood size, and offspring mass). There were no relationships between any measure of reproductive output and feather characteristics between elevations or across years, despite substantial variation in reproductive output in the wider population across this same time. However, birds at the high-elevation site grew their tail feathers significantly faster and had higher fCORT deposition compared to low-elevation birds. These results suggest that although differences in reproductive output and any related signals of associated physiological effort (e.g. fCORT and feather growth rate) may not extend into individual conditions during annual molt, shorter breeding seasons associated with harsher environmental conditions may favor faster feather growth as required by earlier onset of winter. [ABSTRACT FROM AUTHOR]

Published
2024
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49. What's in a mate? Social pairing decisions and spatial cognitive ability in food-caching mountain chickadees.

Author

Branch, Carrie L., Welklin, Joseph F., Sonnenberg, Benjamin R., Benedict, Lauren M., Heinen, Virginia K., Pitera, Angela M., Bridge, Eli S., and Pravosudov, Vladimir V.

Abstract

While researchers have investigated mating decisions for decades, gaps remain in our understanding of how behaviour influences social mate choice. We compared spatial cognitive performance and food caching propensity within social pairs of mountain chickadees inhabiting differentially harsh winter climates to understand how these measures contribute to social mate choice. Chickadees rely on specialized spatial cognitive abilities to recover food stores and survive harsh winters, and females can discriminate among males with varying spatial cognition. Because spatial cognition and caching propensity are critical for survival and likely heritable, pairing with a mate with such enhanced traits may provide indirect benefits to offspring. Comparing the behaviour of social mates, we found that spatial cognitive performance approached a significant correlation within pairs at low, but not at high elevation. We found no correlation within pairs in spatial reversal cognitive performance at either elevation; however, females at high elevation tended to perform better than their social mates. Finally, we found that caching propensity correlated within pairs at low, while males cached significantly more food than their social mates at high elevations. These results suggest that cognition and caching propensity may influence social mating decisions, but only in certain environments and for some aspects of cognition. [ABSTRACT FROM AUTHOR]

Published
2023
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