Long-distance migration is energetically costly and often has a significant impact on bird health and condition. Therefore, understanding the health status of birds during long-distance migration is of ecological interest; however, obtaining invasive health measures is not always feasible or practical. Bird feathers can provide information about individual bird condition independent of invasive and expensive blood tests and have been used previously as indicators of condition, even long after the season of feather growth. Here, we investigated this question using 2 migratory songbirds in North America, Western Palm Warblers (Setophaga palmarum palmarum), which have conspicuous white patches on their tail feathers, and Gray Catbirds (Dumetella carolinensis), which have prominent daily growth bars on their tail feathers. Feathers were collected from birds captured on Jekyll Island, Georgia, during their fall migration. From the feathers we quantified the size of white patches on warbler rectrices and estimated growth bar length (as an index of feather growth rate) on catbird rectrices using image analysis. We also obtained 2 measures of bird health for each species: estimates of white blood cell abundance from blood smears (immune status) and size-corrected body mass (body condition). Analyses of feather traits and how they relate to bird health indicated that warblers (n = 42) with larger white patches had significantly higher body condition indices, although no association with white blood cell abundance, and catbirds (n = 27) with faster feather growth had significantly lower white blood cell abundance, but no association with body condition. Given the utility of these feather characteristics, our results suggest these metrics can be used to provide some insights into the biology of songbirds during one of the most critical portions of the annual cycle, migration.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.