We compared masses of definitive basic and alternate plumages of male
Blue-winged Teal (Anas discors) to evaluate the hypothesis that nutrit
ional investments in basic and alternate plumages are related to the d
uration that plumages are worn and to assess the relative costs of pre
basic and prealternate molts. Because these plumages are worn by males
for approximately equal durations, we predicted that masses of the ba
sic and alternate body plumages would be similar. To assess nutritiona
l stress (demands greater than available resources) associated with mo
lt, we examined the relation between remigial length and structural si
ze and compared predicted and observed plumage masses of Blue-winged T
eal and other ducks. If birds were nutritionally challenged during rem
igial molt, then we predicted remigial length would be influenced by n
utrition lather than size, and remigial length and size would be unrel
ated. Alternate body plumage of male Blue-winged Teal weighed about 10
% more than the basic body plumage; however, masses of both plumages w
ere less than that predicted on the basis of lean body mass. We argue
that deviations between observed and predicted plumage masses were rel
ated to factors other than nutrition. Further remigial lengths were si
gnificantly, albeit weakly, related to structural size. We therefore c
oncluded that, although the potential for molt-induced stress may be g
reatest in small-bodied waterfowl species, there was no clear evidence
that molting male Blue-winged Teal were nutritionally stressed.