A bird assemblage mobs an adult pitviper in southeastern Brazil

Abstract

Birds mostly mob avian or mammalian predators, but harass snakes as well. The mobbed snakes are potential or actual bird predators, but records of birds mobbing vipers are rare. I report herein on an avian assemblage mobbing an adult Jararaca Lancehead (Bothrops jararaca) in the Atlantic Forest of southeastern Brazil. The bird assemblage was composed of 8 species and 11 individuals. The most insistent mobber was a Golden-crowned Warbler. Two bird species dived at close range of the moving pitviper: the Sayaca Tanager and the Short-crested Flycatcher, which dived at the snake 2 and 1 times respectively. The snake seemed undisturbed by the harassing birds, but stopped moving after each of the dives. The Jararaca Lancehead occasionally forage at daytime, climb on vegetation, and prey on birds. Thus, it may actually pose a predation risk to the mobbing birds when they are nesting in the vicinity or when they are much distracted while harassing.