Several factors have been suggested as
defining the amount of copulation share. (1)
The origin of each adult male within the social
unit: parental relationships have been explained
as one mediating factor in the sharing of
copulations as shown in African lions Panthera
leo (Packer et al, 1991) and in white-browed
scrub wrens Sericornis frontalis (Whittingham
et al., 1997) where closely related males show
a higher skew in reproduction versus
“outsiders”, as the gain in inclusive fitness for
subordinates (Clutton-Brock, 1998) will
maintain them in the social unit. (2) The
cooperation in territorial defence is often
explained as a way extra males might
collaborate with the breeding animals in order
to remain in the home range (Cockburn, 1998).
(3) Simple territorial defence can be combined
with overall habitat quality. In low quality
habitat, home ranges have to be expanded to
meet the needs of reproductive females and