Sr. Mcwilliams et Wh. Karasov, Phenotypic flexibility in digestive system structure and function in migratory birds and its ecological significance, COMP BIOC A, 128(3), 2001, pp. 579-593
Citations number
138
Categorie Soggetti
Animal Sciences",Physiology
Journal title
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR AND INTEGRATIVE PHYSIOLOGY
Birds during migration must satisfy the high energy and nutrient demands as
sociated with repeated, intensive flight while often experiencing unpredict
able variation in food supply and food quality. Solutions to such different
challenges may often be physiologically incompatible. For example, increas
ed food intake and gut size are primarily responsible for satisfying the hi
gh energy and nutrient demands associated with migration in birds. However,
short-term fasting or food restriction during flight may cause partial atr
ophy of the gut that may limit utilization of ingested food energy and nutr
ients. We review the evidence available on the effects of long- and short-t
erm changes in food quality and quantity on digestive performance in migrat
ory birds, and the importance of digestive constraints in limiting the temp
o of migration in birds. Another important physiological consequence of fee
ding in birds is the effect of diet on body composition dynamics during mig
ration. Recent evidence suggests that birds utilize and replenish both prot
ein and fat reserves during migration, and diet quality influences the rate
of replenishment of both these reserves. We conclude that diet and phenoty
pic flexibility in both body composition and the digestive system of migrat
ory birds are important in allowing birds to successfully overcome the ofte
n-conflicting physiological challenges of migration. (C) 2001 Elsevier Scie
nce Inc. All rights reserved.