Mi. Sandell et al., PATERNAL CARE IN THE EUROPEAN STARLING, STURNUS-VULGARIS - NESTLING PROVISIONING, Behavioral ecology and sociobiology, 39(5), 1996, pp. 301-309
The extent to which male birds in polygynous species with biparental c
are assist in nestling feeding often varies considerably between nests
of different mating status. Both how much polygynous males assist and
how they divide their effort between nests may have a profound effect
on the evolution of mating systems. In this study we investigated how
males in the facultatively polygynous European starling Sturnus vulga
ris invested in their different nests. The amount of male assistance a
ffected the quality of the offspring. Polygynous males invested as muc
h as monogamous males, but divided their effort asymmetrically between
nests, predominantly feeding nestlings of first-mated (primary) femal
es. Although females partly compensated for loss of male assistance, t
otal feeding frequency was lower at primary females' nests than at mon
ogamous females nests. Secondary females received even less assistance
with nestling rearing, and the extent to which males assisted decreas
ed with the length of the interval between the hatching of the primary
and secondary clutches. These results are contrasted with those from
a Belgian populations of starlings with a much more protracted breedin
g season and thus greater opportunities for males to attract additiona
l mates during the nestling rearing period. The results show that both
the ''defence of male parental investment model'' and the ''asynchron
ous settlement model'' have explanatory power, but that their validity
depends on the potential length of the breeding season.