Summary: Life-history traits as causes or consequences
of social behaviour: why do cooperative
breeders lay small clutches?
* and Hanna Kokko
Department of Animal Ecology, Ecology Building, University of Lund, 223 62 Lund, Sweden,
Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35,
40014 Jyväskylä, Finland and 3
School of Botany and Zoology, Australian
National University, Canberra, ACT 0200, Australia
Cooperatively breeding birds tend to exhibit high adult survival and relatively small clutch sizes.
According to the life-history hypothesis for cooperative breeding, high survival creates con-
ditions for philopatry based on difficulties that dispersers face when competing for territories in
a landscape with slow territory turnover. However, this hypothesis evokes a puzzle because high
fecundity should also lead to problems in territory acquisition because of the large number of