Interference between the sexes in foraging bar-tailed godwits Limosa lapponica

Sexual size dimorphism is common in many bird species. A consequence of sexual size dimorphism is that the larger sex has larger food requirements, and also that it might be dominant over the smaller sex. We studied the foraging behaviour of Bar-tailed Godwits Limosa lapponica, a highly sexually size dimorphic species. Our interest is in intersexual competition and its consequences for habitat use. Male and female Bar-tailed Godwits were distributed non-randomly over the intertidal foraging areas. Males were concentrated on exposed mud flats, while females occurred more along the waterline. Also within these habitat types, the sexes associated with same-sex individuals. Males were more susceptible to intraspecific kleptoparasitism than females, which we suggest is the cause of the unequal spatial distribution of male and female Bar-tailed Godwits. Females seem to monopolise the better quality foraging areas, leaving males the rest