Adaptive nesting behaviour of house sparrows in barn swallow nests in Uttarakhand

Birds (Class Aves) play a vital role in maintaining ecological balance by contributing to insect population control, pollination, seed dispersal, and serving as sensitive indicators of environmental change. Among synanthropic bird species, the barn swallow (Hirundo rustica) and the house sparrow (Passer domesticus) are closely associated with human settlements and rely heavily on man-made structures for nesting. The present study highlights the nest-building patterns of barn swallows and documents interspecific nesting interactions with house sparrows at a communal nesting site in a hilly rural village of Pauri Garhwal, Uttarakhand, India. Observations revealed that barn swallows initiated nest construction mainly during the monsoon season, forming mud-based nests on sheltered structures. In contrast, house sparrows were observed occupying some inactive swallow nests, removing original nesting materials, and modifying nest structures to meet their own nesting requirements. These findings emphasize the adaptive flexibility and behavioural plasticity of rural-associated bird species in response to limited nesting resources within human-dominated landscapes. The study underscores the ecological significance of interspecific nest use as an indicator of changing habitat conditions and highlights the need to conserve bird-friendly nesting spaces to support avian coexistence and biodiversity.