Population status, habitat preference, and nesting characteristics of black-headed ibis Threskiornis melanocephalus Latham, 1790 in southern Rajasthan, India

The black-headed ibis Threskiornis melanocephalus is a medium sized (65-75 cm long) wading, nomadic Ciconiiform waterbird, gregariously frequenting shallow habitats. It is wide-ranging species distributed across the Asian continent and categorized as “Near Threatened” by IUCN (International Union for Conservation of Nature) because of decreasing population status from the last few decades. The present work describes the current population status, habitat preference in response to seasonal variation, and nesting characteristics of black-headed ibis T. melanocephalus in southern Rajasthan, India. Different surveys were performed in the study area at different temporal and spatial scales to assess different aspects. A total of 580 individuals (496 adults and 84 juveniles) were recorded during 2016, while 643 individuals (547 adults and 96 juvenile) in 2017. Juveniles represented 14.7% of the total population. The overall adult-juvenile ratio was 0.16 in 2016 and 0.17 in 2017. The encountered birds were found not significantly different seasonally in distinct microhabitats in both years (p < 0.05); highest number was recorded in seasonal wetlands. Nesting sites were recorded in two districts (i.e. Udaipur and Dungarpur) along with eight other waterbird species. Cattle egrets Bubulcus ibis was the most commonly associated nesting species, while babul Acacia nilotica and vilayati babul Prosopis juliflora were the most preferred nesting tree species.