Variation In Plumage Coloration Of Eastern Bluebirds (Sialis Sialis) In Relation To Weather And Geography

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Mary-Catherine Warnock (Creator)
Appalachian State University (ASU )
Web Site:
Lynn Siefferman

Abstract: Plumage coloration is thought to convey individual quality and influence reproductive success for many species. Few studies have investigated how weather variation during molt impacts ornamental traits. Eastern bluebirds (Sialis Sialis), an insectivorous passerine, display sexually dichromatic UV-blue structural based and chestnut melanin-based plumage. The UVblue coloration is likely to be sexually selected as it indicates nutrition stress, individual quality, and influences reproductive success via male-male interactions. Melanin coloration is less sensitive to environmental conditions during molt. In my thesis, I examine 1) an Alabama population and investigate whether plumage coloration tracks weather during molt and 2) use museum specimens dating back to 1895 to investigate how geography, weather, and year of collection influence plumage coloration. My results demonstrate that 1) Alabama birds displayed more ornamented UV-blue plumage in years following late summers with cooler, wetter weather, and 2) museum specimens displayed brighter UV-blue plumage and chestnut-plumage when collected in warmer, easterly locations. Overall, the Alabama population results suggest that structural based plumage is more affected by climate variation than melanin-based coloration. The museum specimen results suggest both plumage types are affected by geographical location and climate, yet structural coloration is more affected by year of specimen collection.

Additional Information

Honors Project
Warnock, M. (2017). "Variation In Plumage Coloration Of Eastern Bluebirds (Sialis Sialis) In Relation To Weather And Geography." Unpublished Honors Thesis. Appalachian State University, Boone, NC.
Language: English
Date: 2017
Sexual Selection, Phenotypic Change, Structural, Melanin

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