Composition and foraging behaviour of mixed‐species flocks led by the Grey‐cheeked Fulvetta in Fushan Experimental Forest, Taiwan

Thirty‐two species were recorded in mixed‐species bird flocks led by the Grey‐cheeked Fulvetta Alcippe morrisonia in Fushan Experimental Forest, Taiwan. Flocks averaged (± se) 5.8 ± 0.2 species and 51.4 ± 2.7 birds. Most participants were resident species (86.3%), some were elevational migrants (12.6%) and a few were latitudinal migrants (1.1%). Flock size was determined primarily by the abundance of Grey‐cheeked Fulvettas, the most abundant species (68.1%). Flocks moved at an average rate of 10.8 ± 0.7 m/min, with larger flocks moving faster than smaller flocks. In moving flocks, canopy species were usually near the front, while understorey species usually followed. Fulvettas gave higher‐intensity alarm calls and dived down more frequently in response to avian threats, especially raptors, than to non‐avian threats. The overall foraging niche‐breadth of the fulvetta was greater than that of any attendant species. Each species in a flock had a unique foraging niche. Most attendant species exhibited low foraging niche‐overlap with the Grey‐cheeked Fulvetta. Both the predator avoidance and the foraging efficiency hypotheses for mixed‐species flocking were supported. The Grey‐cheeked Fulvetta plays a critical role in the function of mixed‐species flocks. A large flock formed around the Grey‐cheeked Fulvetta provides attendant species with numerous opportunities for obtaining food and protection from predators.