E. Matthysen, Foraging behaviour of Nuthatches (Sitta europaea) in relation to the presence of mates and mixed flocks, J ORNITHOL, 140(4), 1999, pp. 443-451
Nuthatches (Sitta europaea) usually forage in pairs outside the breeding se
ason. I investigated whether foraging site selection in winter (tree specie
s, height, substrate size) differed between sexes and whether this differen
ce was related to the presence of mixed-species flocks. Foraging sites of p
air members foraging together were highly correlated. In the rare cases whe
n each used different tree species, males foraged significantly more often
on the preferred oak trees than females. Males foraged significantly lower
than females in some territories, but not in others. The reasons for this s
ignificant Variation between pairs remains unexplained. Males also foraged
lower than females in the company of mixed flocks. These differences are pr
obably better explained as avoidance of the dominant male by the subordinat
e female, rather than specialization in resource use to avoid competition.