Tolerance of disturbance by humans in long-time resident and recent colonist urban doves

Background A critical trait for successful urban dwelling by birds is the ability to tolerate high levels of disturbing stimulation by humans. If such tolerance is partly acquired gradually after colonization,species with a long history of residence in cities are likely to be more tolerant of such stimulation than recent urban colonists,but this has not often been tested.

Methods We tested whether introduced Rock (Columba livia) and Spotted (Streptopelis chinensis) Doves,historically long-term residents of Melbourne,Australia,were more tolerant of disturbance by humans than the very recent colonist,the native Crested Pigeon (Ochyphaps lophotes) by comparing the Flight Initiation Distances (FID) and time allocations to vigilance during foraging of all three species in urban Melbourne. That all three species are members of the Columbiformes reduces the possibility that any species differences in tolerance are simply phylogenetic in origin.

Results Flight initiation distance was shorter in Rock Doves than in the other two species,which did not differ in approachability by a human. Rock Doves retreated from an approaching human mainly by walking a relatively short distance,Crested Pigeons mainly by running a relatively short distance and Spotted Doves primarily by flying a comparatively long distance. The time allocation to anti-predator vigilance of Rock Doves was smaller than that of the other two species,whose allocations were similar.

Conclusions The very recent colonist of eastern Melbourne,the Crested Pigeon,was not the least tolerant of disturbance by humans of the three related species. Natural selection for tolerance therefore probably cannot entirely explain the pattern of tolerance evident among these urban dove species and behavioural flexibility is probably involved. Length of residency in a city is not an infallible guide to a species' level of tolerance of disturbance by humans.