Remnant microhabitats are important for bird habitat selection and plant regeneration in the fragmented habitat. However, empirical information on the consequences of how microhabitat use by birds affects the early recruitment of plants is lacking.

In this study, we evaluated whether microhabitat selection by the Black Bulbul (Hypsipetes leucocephalus) (J. F. Gmelin, 1789) impacts the early recruitment of the endangered tree species, the Chinese Yew (Taxus chinensis (Pilger) Rehd), in a fragmented forest over a 4-year period (2011–2012, 2018–2019).

Our results showed the main factors affecting H. leucocephalus microhabitat selection were distance to the nearest T. chinensis mature tree, herb cover and density, leaf litter cover, and vegetation type. Moreover, the results of logistic regression also highlighted the importance of elevation, distance to light gap and roads, tree cover in bird microhabitat selection. Furthermore, the seed emergence rate in microhabitats used by birds did not differ from the natural forest, which was related to five factors of bird microhabitat. The Random Forest model showed that seedling emergence rate was increased with leaf litter cover and distance to fallen dead trees, but decreased in relation to herb cover, slope, and elevation.

Our results highlight the importance of remnant microhabitats in fragmented forests for sustaining forest ecology and optimal management. The contribution of microhabitats used by birds to plant recruitment provides insights into how frugivore species contribute to plant regeneration, which should be incorporated in future conservation and management practices of fragmented forests.

The most dominant global threat to natural forests and their biodiversity is land-cover change, which has negative impacts on both species persistence and ecosystem functions. Land-cover change could alter animal behaviour and disrupt seed dispersal mutualisms. However, its effects on the role of bird functional traits in seed dispersal are not well studied.

In the present study, we assessed the contributions of bird functional traits (behavioural traits: food habit, foraging pattern, foraging frequency, and habitat specialisation; morphological traits: weight, body length, wing length, and tail length) to both seed removal patterns and seed dispersal distances of an endangered and native tree species, Chinese yew (Taxus chinensis), in farmland, patchy habitat, and natural habitat, of southeast China.

We found that the ability of T. chinensis trees to form seed dispersal mutualisms with local birds varied across the different disturbed habitats. As a consequence of these mutualisms, more seeds were removed by birds from the patchy habitat than from the other two habitats. The number of seeds removed increased with bird foraging frequency. Moreover, the dispersal distance from the three habitats differed, and the longest dispersal distances were observed at both the patchy habitat and the farmland site. Seed dispersal distance increased with bird tail and wing length.

Our Results highlight the importance of bird functional traits in the seed dispersal patterns of endangered trees across disturbed forest habitats, which should be considered for tree conservation and management.