DOMINANT RED JUNGLEFOWL (GALLUS-GALLUS) HENS IN AN UNCONFINED FLOCK REAR THE MOST YOUNG OVER THEIR LIFETIME

The evolutionary success of individuals must ultimately be evaluated in terms of their lifetime contribution of mature young to the breeding population. The greater lifetime breeding success of the more dominant hens in an unconfined nock of Red Junglefowl (Gallus gallus) gave crucial evidence why female dominance hierarchies have evolved in this species. The number of chicks reared to independence by 28 hens of one flock from 1982 to 1988 was significantly associated with a hen's dominance, life-span, and year of hatching. Of these, dominance was by far the most important factor. It, by itself, could explain differences in the number of chicks reared as shown by log-linear analysis. This suggests that the associations with life-span and year of hatching may result from the fact that these are correlated with dominance. The top 3 hens in the peck order added more offspring of breeding age to the population than did the remaining 25 adult hens of the nock. Eleven of the 28 hens reared no young successfully.