Mangrove-associated Avifauna in Kerala: A Comparative Study of Avian Biodiversity at Mangalavanam and Kadalundi

Abstract

Mangrove ecosystems provide important habitats for resident and migratory birds and support ecological functions in coastal landscapes. This study compared avian biodiversity in two mangrove-associated wetland systems in Kerala, India: Mangalavanam Bird Sanctuary, an urban sanctuary in Ernakulam, and Kadalundi-Vallikunnu Community Reserve, a less disturbed estuarine site along the Kozhikode-Malappuram coastal belt. Monthly field surveys were conducted from August 2022 to July 2024 during morning and evening periods of peak bird activity. Bird species were recorded using point-count transects, visual identification, acoustic cues and opportunistic sightings. Species richness, Shannon-Wiener diversity and species evenness were used to assess community structure. Mangalavanam recorded 24 bird species from 19 families, whereas Kadalundi recorded 40 species from 20 families. Kadalundi showed higher avian diversity, with a Shannon-Wiener value of 3.17, compared with 2.86 for Mangalavanam. In contrast, Mangalavanam showed higher species evenness (0.90) than Kadalundi (0.79), indicating a more even distribution of individuals among recorded species at the urban site. The findings indicate that Kadalundi supports greater species richness and a wider range of functional groups, whereas Mangalavanam retains ecological value despite urban pressures. The study highlights the need for continued monitoring and conservation of both rural and urban mangrove habitats in Kerala.