Seed dispersal by birds and squirrels: A study of fruiting trees and their ecological interactions

Abstract

Seed dispersal is a critical ecological process that maintains plant regeneration, biodiversity, and ecosystem stability, particularly in fragmented urban landscapes. The present study investigates the role of birds and squirrels in mediating seed dispersal within the green campus of Isabella Thoburn College. Field observations were conducted from November 2025 to January 2026 across five campus zones using focal tree and focal animal sampling methods. A total of 11 fruiting tree species, 9 bird species, and one mammalian disperser, the Indian Palm Squirrel, were recorded interacting within the seed dispersal network. Across the three observation phases, 50 total dispersal events were documented, with 15 observations in Phase I, 17 in Phase II, and 18 in Phase III, indicating increasing dispersal activity during peak fruiting periods. Feeding behaviour constituted the dominant activity (44% of total observations), followed by dropping (28%), carrying (22%), and swallowing (6%), reflecting varied dispersal strategies among species. Among birds, the Common Myna and Jungle Babbler showed the highest interaction frequencies, while squirrels contributed significantly through carrying and caching behaviors that enhance seed deposition in favorable germination microsites. The dominance of fruiting trees such as Ficus religiosa, Ficus benghalensis, Psidium guajava, and Mangifera indica provided continuous food resources supporting disperser activity. Zone-wise analysis revealed the highest dispersal interactions near areas with dense fruiting vegetation and lower human disturbance. The findings highlight the complementary roles of birds in long-distance dispersal and squirrels in localized seed placement.