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Abstract

Kelp gulls (Larus dominicanus), a very common and widespread species of seabird in the Southern Hemisphere, were observed picking pieces of sloughed skin from a southern right whale's (Eubalaena australis) back. When attacked by these birds, whales reacted violently by arching the back, raising the head and tail, and submerging quickly, swimming away under water. Two episodes of klep gull harassment on right whales were observed during part of an ongoing study of the distribution and behavior of the Brazilian right whale population on its nursery ground along the southern coast of Santa Catarina State. The first episode of harassment occurred on August 31 1998 at Rosa Beach. The behavior of a mother-calf pair was recorded during 4 hours of observation on the day when the gull harassment took place, and on five subsequent days. During all subsequent observations, the behavior of the pair followed the same patterns recorded in the first period of observation during the day of the attack, and no other gull attack was observed. On September 03 2000 a second episode of mother-calf harassment by kelp gulls was observed at Garopaba Beach. This pair displayed the same response to the gull attack as the first one observed in 1998. Any potential source of harassment, even a rare event such as the gull attack reported here, may impact on the recovery of this population. The continuing study of this population is necessary to monitor the long-term effect and potential increase in the frequency os these attacks.