Hummingbird diversity in a fragmented tropical landscape in the Choco biogeographic zone

Forest loss and fragmentation drive widespread declines in biodiversity. However, hummingbirds seem to exhibit relative resilience to disturbance, characterized by increasing abundance alongside declining species richness and evenness. Yet, how widespread this pattern may be, and the mechanisms by which it may occur, remain unclear. To fill in this knowledge gap, we investigated habitat-and site-level patterns of diversity, and community composition of hummingbirds between continuous forest (transects n = 16 in similar to 3500 ha) and more disturbed surrounding fragments (n = 39, 2.5-48.0 ha) in the Choco rain forest of northwestern Ecuador. Next, we assessed within-patch and patch-matrix characteristics associated with hummingbird diversity and composition. We found higher hummingbird species richness in forest fragments relative to the continuous forest, driven by increased captures of rare species in fragments. Community composition also differed between continuous forest and fragments, with depressed evenness in fragments. Increased canopy openness and density of medium-sized trees correlated with hummingbird diversity in forest fragments, although this relationship became nonsignificant after applying false discovery rate (p < .01). Higher species richness in fragments and higher evenness in the continuous forest highlight the complex trade-offs involved in the conservation of this ecologically important group of birds in changing Neotropical landscapes.

Automated summary

Forest loss and fragmentation lead to declines in biodiversity, but hummingbirds show relative resilience to disturbance with increasing abundance and declining species richness and evenness. However, the extent and mechanisms of this pattern remain unclear. To investigate, we compared hummingbird diversity and community composition between continuous forest and disturbed fragments in northwestern Ecuador. We found higher species richness in fragments, driven by rare species captures, and differences in community composition. Canopy openness and tree density correlated with hummingbird diversity in fragments. Trade-offs between species richness in fragments and evenness in continuous forest are important for conserving this ecologically significant bird group in changing Neotropical landscapes.