Kelp Gulls Exploit Food Provided by Active Right Whales

A widespread feeding association between Kelp Gulls (Larus dominicanus) and Right Whales (Eubalaena glacialis) was observed in shallow waters of the Valdès Peninsula, Argentina in winter. Observations made from a yacht and underwater in August 1991 showed that gulls foraging on the shore were selectively attracted to active whales, particularly when whales were numerous and in shallow waters. Tumultuous movements by whales induced an upwelling of mixed sediment, benthic invertebrates and pieces of dead skin. The high frequency of interactions (3/h) and proportion of birds involved (60-70%) suggest that this food supply is important for gulls when alternative resources are lacking. Their rapid arrival (9 min) to extra food deposited near quiet animals indicates that gulls have learned to rely on whale behavior to locate this food. As with gulls in general, such local and seasonal feeding behavior supplements numerous other techniques used by this widespread and opportunistic species.