RECORDS OF MOBBING BEHAVIOR IN VENEZUELAN WILD BIRDS

Abstract

Mobbing is a survival strategy in which birds attack enemies to drive them from the vicinity. This paper reports mobbing behavior events among wild bird species of Venezuela. A total of 31 species from 15 families were recorded in 130 mobbing events. Individual mobbing was the widespread strategy, recorded in 24 species (77%) and 82 mobbing events (63%). Birds tended to mob individually when the enemy was flying but they inclined to do so in groups when the enemy was perched (χ2 =18.191, p<0.05). However, 16 species (52%) required additional assistance of conspecifics, and only three species (10%) were assisted by non-conspecific allies. Anti-predatory was the widespread function, recorded in 27 species (87%) and 106 mobbing events (82%). 22 species (71%) mobbed one bird of prey at least, and 79 mobbing events (61%) were against typical raptor-shaped birds. But mobbing also was performed for other purposes: six species (19%) mobbed for food resource protection in 17 mobbing events (13%) while other four species (13%) mobbed for site defense in five events (4%). Mobbing behavior was recorded at breeding time in 16 species (53%), and 75 mobbing events (58%) occurred at that period. Seven mobber species (23%) were also mobbed. Most mobbing events (98%) were initiated by the weaker species. Highly significant differences were found in body size (W: 4471.0; p>0.01) and body mass (W: 4452.5; p>0.01) between the mobber and mobbed species. In general, a mobber bird engaged in mobbing with other birds of same body size and body mass up to 5.6 times larger and 117.5 heavier. Only the Roadside Hawk Rupornis magnirostris and the Tropical Kingbird Tyrannus melancholichus were exposed to true danger when they mobbed the Great Black-Hawk Buteogallus anthracinus. Recorded information improves the repository of available knowledge in Venezuela and the Neotropical region.