A natural experiment on the condition-dependence of achromatic plumage reflectance in black-capped chickadees
PLoS ONE
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Abstract
Honest advertisement models posit that only individuals in good health can produce and/or maintain ornamental traits. Even though disease has profound effects on condition, few studies have experimentally tested its effects on trait expression and even fewer have identified a mechanistic basis for these effects. Recent evidence suggests that black and white, but not grey, plumage colors of black-capped chickadees (Poecile atricapillus) are sexually selected. We therefore hypothesized that birds afflicted with avian keratin disorder, a condition that affects the beak and other keratinized tissues, would show reduced expression of black and white, but not grey, color. UV-vis spectrometry of black-capped chickadees affected and unaffected by avian keratin disorder revealed spectral differences between them consistent with this hypothesis. To elucidate the mechanistic bases of these differences, we used scanning electron microscopy (SEM), electron-dispersive x-ray spectroscopy (EDX) and a feather cleaning experiment. SEM showed extreme feather soiling in affected birds, and EDX revealed that this was most likely from external sources. Experimentally cleaning the feathers increased color expression of ornamental feathers of affected, but not unaffected, birds. These data provide strong evidence that black and white color is an honest indicator in chickadees, and that variation in feather dirtiness, likely due to differences in preening behavior is a mechanism for this association.
Suggested Citation
D'Alba, L., Van Hemert, C.R., Handel, C.M., Shawkey, M., 2011, A natural experiment on the condition-dependence of achromatic plumage reflectance in black-capped chickadees: PLoS ONE, v. 6, no. 10, https://doi.org/10.1371/journal.pone.0025877.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | A natural experiment on the condition-dependence of achromatic plumage reflectance in black-capped chickadees |
| Series title | PLoS ONE |
| DOI | 10.1371/journal.pone.0025877 |
| Volume | 6 |
| Issue | 10 |
| Publication Date | October 03, 2011 |
| Year Published | 2011 |
| Language | English |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | PLoS ONE |