Jd. Parrish et Tw. Sherry, SEXUAL HABITAT SEGREGATION BY AMERICAN REDSTARTS WINTERING IN JAMAICA- IMPORTANCE OF RESOURCE SEASONALITY, The Auk, 111(1), 1994, pp. 38-49
We tested the hypothesis that wintering populations of American Redsta
rts (Setophaga ruticilla) segregate into different habitats by sex in
response to ecological conditions associated with an extensive dry sea
son, which typically develops after migrants arrive in northern Neotro
pical sites. Sex-specific distribution and overwinter persistence of r
edstarts were quantified at a Jamaican mangrove-scrub ecotone. We also
contrasted vegetation structure and food availability in winter terri
tories of the two sexes and in both habitats within and between season
s. Male and female redstarts were significantly segregated by habitat,
with males holding territories in mangroves and females predominantly
in contiguous scrub habitat. However, we found no significant sex-bas
ed difference in overwinter persistence on territories. The average ma
ngrove territory had a higher canopy and more-open understory, higher
relative humidity, and greater insect biomass within a season for seve
ral insect orders important in redstart diets. Canopy (leaf) cover and
abundances of several insect taxa remained more constant over the dry
season in mangrove than in scrub habitat. We argue that these between
-habitat differences, especially seasonal stability of vegetation feat
ures and food abundances in mangrove habitats, affect winter habitat q
uality for nonbreeding redstarts.