Arpitha Jayanth
Islands harbour unique biodiversity. Due to their isolation and small sizes, islands are also more vulnerable to anthropogenic disturbances such as hunting, logging, and the introduction of invasive species. Consequently, many islands have lost native and endemic species, disrupting vital ecosystem processes that maintain biodiversity. Birds play vital ecological roles on islands, and their extinctions can disrupt critical ecosystem processes. Over 95% of bird extinctions have occurred on islands worldwide.
A perched Andaman Bulbul, an endemic frugivorous bird. © Aditya Gadkari.
Our understanding of anthropogenic threats on native frugivorous birds and their role in ecosystem processes on islands is poor. Logging can alter plant communities and cause loss of key frugivores, with downstream consequences for seed dispersal and forest regeneration. Furthermore, islands are relatively depauperate compared to mainland, harbouring fewer seed disperser species. The role that these species play towards dispersing seeds are likely to be non-redundant and disproportionately higher in islands. Thus, disruption of the interactions between plants and frugivores will have greater consequences for seed dispersal on islands.
The Andaman & Nicobar Islands (part of the Indo-Burma biodiversity hotspot) are home to a unique set of flora and fauna, including 21 endemic bird species and about 315 endemic plant species. They also harbour a diverse set of ecosystems, including evergreen and deciduous forests in a relatively small area. However, they have been facing intense logging pressures, resulting in forest loss and degradation. Past studies have focused on documenting the island’s biodiversity, and the impacts of logging on plant species composition. Understanding the impacts of logging on frugivores and seed dispersal across habitats is a vital knowledge gap in light of ongoing and novel threats to this fragile ecosystem.
We aim to shed light on whether logging disrupts seed dispersal – a key ecosystem function – by impacting the island’s plants and birds, across two forest (habitat) types. Specifically, we will document the impact of logging on 1) bird diversity and densities, 2) diversity and abundance of woody plants, and 3) bird-mediated seed dispersal (at the fruit removal stage) of fleshy-fruited plants across evergreen and deciduous forests in South Andaman Island. Through this project, we also aim to understand the status of several threatened and endemic species in this understudied and vulnerable ecosystem.
Header: Andaman Cuckoo-Dove, an endemic bird, feeding on the fruits of Heteropanax fragrans. © Aditya Gadkari