Study on the Distribution of House Sparrow (Passer domesticus) with Respect to the Availability, Preference, and Occupancy of the Natural Nesting Sites along the Rural, Suburban, and Urban Gradients in Madurai District, Tamil Nadu, India

Nowadays, human-dependent birds are declining in heavily populated areas, in general. House sparrows are one of the common urban birds that are well-known for their tendency to live near humans. However, the disappearance of this species has been reported widely in India. According to the Indian Council of Agricultural Research (ICAR), the sparrow population in Andhra Pradesh has dropped by 80% and in Kerala, Gujarat, and Rajasthan it has declined by 20%, while the decline in coastal areas of India was as sharp as 70% to 80%. The decline in house sparrow numbers should therefore be examined in relation to human activity patterns over time. Hence, the objective of this study is to determine the distribution of the house sparrow population in the Madurai District as well as identify its natural nesting sites according to their structural preferences and distribution along rural, suburban, and urban gradients. A line-transect method was used to survey the 169 study sites in the Madurai District and house sparrow nesting behavior was documented in photographs and videos. Based on the data, sparrows were found in 109 places, wherein 80% of the population was found in urban habitats and 62% in rural habitats. The 53 types of natural nesting sites identified were classified as Cavity-type nesting sites in Building structures (CB), Cavity-type nesting sites in non-Building structures (CNB), and Non-Cavity type nesting sites in non-Building structures (NCNB). A total of 1820 natural nests were discovered, of which 1338 were located in nesting sites of the CB type, which came in 19 different varieties, 253 in those of the CNB type, which came in 15 variations, and 229 in those of the NCNB type, which came in 19 types. The most preferred nesting site in each of the groups was identified to be the space between wooden joists in buildings (CB), pipe holes in highway bridges (CNB), and electric meter boxes (NCNB). Along the rural, suburban, and urban gradients, it was discovered that CB-type nesting sites were the most favoured nesting locations. A high positive association between the population of house sparrows and the amount of accessible natural nesting places was discovered (R = 0.99). Being opportunistic secondary cavity-nesters, house sparrows exhibit flexibility in choosing nesting sites, in the absence of cavity-type nests. Therefore, it can be concluded that, by providing suitable nesting sites, this species could be conserved in areas with a declining population index.