Presentation Title

Effects of Age, Rainfall, and Temperature on Feather Colouration in Mountain Bluebirds

Format of Presentation

Poster to be presented the Friday of the conference

Abstract

In sexually dichromatic birds, ornamentation can play an important role in mate selection. Males with greater ornamentation tend to experience greater reproductive success, presumably because feather colouration provides an indicator of individual quality or is simply more attractive to females. While numerous studies have examined factors affecting ornamentation in birds that possess carotenoid-based plumage coloration (where carotenoids ingested through the bird’s diet are directly deposited into the feather, creating red, orange, or yellow plumage colour), less is known about the factors that affect birds that exhibit structural-based plumage coloration (where the color is based on microscopic feather structures). This study attempts to explore the effects of individual age, rainfall, and temperature on feather coloration in mountain bluebirds, a species with structurally-based UV-blue plumage coloration. Feathers were collected during bluebird breeding seasons (May-August) from 2011-2019 in the Kamloops area, and scanned using reflectance spectroscopy. An R-based color analysis program was used to analyze reflectance measurements, and the results were then analyzed using principal component analysis and mixed effects models to compare feather colouration on both an individual and population level. Within individuals, we found that colour decreased in older males in both rump and tail feathers, while at a population level, young males and females showed greater ornamentation as they aged. While the results from the weather models are not yet well understood, it appears that males and females were affected differently by rainfall and temperature, in terms of resulting plumage colouration.

Department

Biological Sciences

Faculty Advisor

Matt Reudink

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Effects of Age, Rainfall, and Temperature on Feather Colouration in Mountain Bluebirds

In sexually dichromatic birds, ornamentation can play an important role in mate selection. Males with greater ornamentation tend to experience greater reproductive success, presumably because feather colouration provides an indicator of individual quality or is simply more attractive to females. While numerous studies have examined factors affecting ornamentation in birds that possess carotenoid-based plumage coloration (where carotenoids ingested through the bird’s diet are directly deposited into the feather, creating red, orange, or yellow plumage colour), less is known about the factors that affect birds that exhibit structural-based plumage coloration (where the color is based on microscopic feather structures). This study attempts to explore the effects of individual age, rainfall, and temperature on feather coloration in mountain bluebirds, a species with structurally-based UV-blue plumage coloration. Feathers were collected during bluebird breeding seasons (May-August) from 2011-2019 in the Kamloops area, and scanned using reflectance spectroscopy. An R-based color analysis program was used to analyze reflectance measurements, and the results were then analyzed using principal component analysis and mixed effects models to compare feather colouration on both an individual and population level. Within individuals, we found that colour decreased in older males in both rump and tail feathers, while at a population level, young males and females showed greater ornamentation as they aged. While the results from the weather models are not yet well understood, it appears that males and females were affected differently by rainfall and temperature, in terms of resulting plumage colouration.