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THE ROLE OF FOOD AVAILABILITY IN THE WINTERING ECOLOGY OF HERMIT THRUSHES ( CATHARUS GUTTATUS ) by NORA E . DIGGS ( Under the Direction of
| Content Provider | Semantic Scholar |
|---|---|
| Author | Cooper, Robert J. |
| Copyright Year | 2008 |
| Abstract | The role of diet in limiting migratory birds during the non-breeding period is poorly understood in part due to the complexities of quantifying food availability and avian diet. We tracked overwinter changes in arthropod and fruit availability for the short-distance migratory bird, the Hermit Thrush (Catharus guttatus), in a southeastern mixed hardwood-pine forest. Fruit availability declined overwinter and arthropods tracked changes with temperature. Concurrently, using fecal samples and stable isotopes, we tracked diet consumption. Fruit declined in fecal samples from early to mid season and δC and δN isotope signatures in blood became more enriched consistent with a decline in fruit consumption and an increase in arthropod consumption. Larger-bodied birds, predominately males, maintained territories with higher arthropod abundance and had a greater proportion of arthropods in their diet. Largerbodied birds experienced less variation in diet (as indicated by δC) and fat loads overwinter, suggesting that smaller bodied females gain fat midwinter to cope with unpredictable and lowerquality resources. These data are consistent with both a size-mediated form of dominance and sexual habitat segregation such that smaller bodied birds, largely females, are behaviorally excluded from optimal territories. Future research should focus on the long-term consequences of food limitation and size and sex-mediated dominance behavior on both within season condition of birds and on subsequent breeding success and survival. INTRODUCTION Food availability often has been shown to be the key limiting resource for birds during the nonbreeding season (Hutto 1985, Strong and Sherry 2000, Johnson and Sherry 2001, Sherry et al. 2005, Studds and Marra 2005, Brown and Sherry 2006). In tropical regions, the onset of |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://getd.libs.uga.edu/pdfs/diggs_nora_e_200812_ms.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
