Abstract
Effects of anthropogenic pressures on birds of the Andaman Islands have been documented to some extent, however studies on the effect of human activities on the behavioural response of these birds are limited. This study assessed the anti-predatory behaviour (flush response - FR and flight initiation distance - FID) of three owl species (Otus sunia, Otus balli, and Ninox obscura) in response to human stimuli and factors influencing it on the Andaman Islands. In total, 63 % of owls flushed from their roost sites in response to approaching human, and such a response varied between species. Similarly, FID varied widely among the species ranging from 4.23 to 6.73 m. The FR of N. obscura was influenced by the count of climbers, presence of spine, and branch status, while roost height, ambient temperature, and lower count of climbers contributed to a higher FID. For the two Otus species, camouflage and pairing were found to influence their FR while FID of O. balli was influenced by roost height, pairing, and presence of spines. Our results indicated that the anti-predatory behaviour of owls on the Andaman Islands was species- and site-specific and prolonged disturbance to their roost sites may affect the survival and reproductive rate of these owls.
Highlights
The presence of people in bird habitats can be considered as a form of disturbance to the birds because they may perceive humans as potential predators, much like their natural predators (Walther 1969)
The response of birds to humans has been evaluated in different ways and the most common measures are flush responses (FR) and flight initiation distance (FID), the distance at which the bird decides to flee in response to an approaching human
We found no difference in the FID (t= -0.959, df= 51, p= 0.342) and FR (X2= 0.02, df= 1, p= 0.886) between the habitat types and we pooled our data for N. obscura
Summary
The presence of people in bird habitats can be considered as a form of disturbance to the birds because they may perceive humans as potential predators, much like their natural predators (Walther 1969). In such situations, birds either flee or show alertness by assessing the level of threat that such human presence poses to them (such as the mode and direction of approach by people) (Grubb & King 1991; Cooper 1997; Sapolsky et al 2000; Papouchis et al 2001; Cooper 2003). There have been many studies on the effects of human disturbance on the nesting of various bird species (Watson 1993; Dowling & Bonier 2018; Collins et al 2019) but, except for one study, research on the effect of human activities on roosting owls is limited
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