Olrog’s Gulls capture prey by walking along the exposed intertidal or in shallow water and by surface seizing or, occasionally, by surface plunging in shallow water (Martinez et al. 2000, Copello and Favero 2001, Delhey et al. 2001a, Gatto et al,. in press). When foraging in water by walking or swimming, prey is taken by partially o completely submerging the head (Delhey et al. 2001a, Gatto et al., in press). When feeding around fishing boats arriving to port, gulls capture prey by dipping (Martinez et al. 2000). Capture and intake rates of birds foraging at the Mar Chiquita lagoon were similar between age classes (Copello and Favero 2001).
Olrog’s Gulls are colonial, breeding at relatively high nest densities (see Reproduction). No information is available on territorial behavior of foraging individuals during both the breeding and non breeding season.
Olrog’s Gulls are monogamous. No studies have been conducted on sexual behavior.
Social and interspecific behavior
Olrog’s Gulls are colonial, nesting in dense aggregations (see Reproduction). At feeding areas and throughout the year, Olrog’s Gulls are seen solitary or in pairs (Delhey et al. 2001a) and in small groups (Escalante 1984, Martinez et al. 2000, Copello and Favero 2001, Favero et al. 2001, Howell and Dunn 2007). Interspecific interactions have been recorded between Olrog’s and juvenile Kelp gulls feeding on barnacles, during which Kelp Gulls showed aggressive behavior and displaced the Olrog’s Gulls in 84% of cases (Delhey et al. 2001a). Both intraspecific and interspecific kleptoparasitism, mainly by Kelp Gulls, was recorded in wintering areas (Martinez et al. 2000).
No information is available.