Meeting Abstract

P3.42  Tuesday, Jan. 6  Feather Growth Bars Do Not Predict Nutritional Status in Nestling Eastern Bluebirds ELDERBROCK, Emily K.*; KERN, Michael D. ; LYNN, Sharon E. ; The College of Wooster; The College of Wooster; The College of Wooster eelderbrock09@wooster.edu

Ptilochronology is a method of determining nutritional status in adult birds by measuring the width of growth bars on their feathers. The width of a pair of adjacent light and dark growth bars represents the amount of growth during a 24-hour time period. Thus, ptilochronology assists in providing a complete record of the daily nutrition of a bird during the growth of the feather. Ptilochronology has been validated in the induced feathers of many species of adult birds, but a recent study suggests that this technique may not be applicable to first developed wing feathers in nestlings. To further investigate this finding, we performed an experiment with Eastern Bluebird (Sialia sialis) nestlings in which we examined the relationship between the width of the feather growth bars on two developing wing feathers of chicks and other measures of their growth, including wing length, tarsus length, and body mass. We predicted that if the method of ptilochronology is applicable to nestling bluebirds, a significant correlation between daily growth and the width of the growth bars on these feathers would exist. However, we found no correlation between the measures of growth and the width of the feather bars. Furthermore the bars were found to be approximately half the width that was expected for a 24-hour period based on daily growth rates of the feathers themselves. Thus, our data support previous findings in nestlings of other species, suggesting that ptilochronology may not be a reliable method in determining nutritional status in nestlings.