Pre-migratory life history stages of juvenile Arctic birds: costs, constraints, and trade-offs.
Ecology
; 88(11): 2729-35, 2007 Nov.
Article
em En
| MEDLINE
| ID: mdl-18051640
ABSTRACT
Many young birds on the Arctic tundra are confronted by a challenging task they must molt their feathers and accumulate fat stores for the autumn migration before climatic conditions deteriorate. Our understanding of the costs and constraints associated with these stages is extremely limited. We investigated post-juvenal molt and premigratory fattening in free-ranging juvenile White-crowned Sparrows (Zonotrichia leucophrys gambelii) on the Arctic tundra. We found evidence for trade-offs between premigratory fat accumulation and molt heavily molting birds had significantly less fat. Birds increased the rate of fat accumulation as the season progressed, but we found no evidence of a similar increase in rate of molt. Using a controlled captive study to isolate the energetic costs of body feather replacement, we found no difference in fat or size-corrected mass of birds actively growing body feathers as compared to controls. Molting birds, however, consumed 17% more food than controls, suggesting a significant cost of body feather growth. Our results provide evidence of significant costs, constraints, and trade-offs associated with post-juvenal molt and premigratory fat accumulation in young Arctic birds.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ingestão de Energia
/
Tecido Adiposo
/
Muda
/
Migração Animal
/
Pardais
Tipo de estudo:
Health_economic_evaluation
Limite:
Animals
Idioma:
En
Revista:
Ecology
Ano de publicação:
2007
Tipo de documento:
Article
País de afiliação:
Estados Unidos