Data from: Forest fragmentation and loss reduce richness, availability, and specialization in tropical hummingbird communities

Hummingbirds are important pollinators of many native Neotropical plants
but their abundance and diversity in landscapes dominated by intensive
human uses such as agriculture have rarely been examined, despite such
land-uses prevailing in the tropics. We examined how tropical
deforestation affects hummingbird community structure in premontane forest
patches embedded in a tropical countryside of Coto Brus Canton, Costa
Rica. We captured hummingbirds in fourteen landscapes representing a
gradient in patch size and forest amount, and tested for the effects of
these variables on (1) hummingbird captures at flowers (pollinator
availability); (2) species richness; and (3) filtering of functional
traits. After accounting for sampling effects, both hummingbird
availability and species richness declined by 40% and 50%, respectively,
across the gradient in deforestation that we observed (9–66% forest within
1000 m). Focal patch size was the strongest predictor, even after
statistically accounting for the amount of forest and matrix composition
of landscapes. These reductions in availability and richness were well
predicted by functional traits; morphologically specialized species with
the capacity to transport long-distance outcrossed pollen and low
functional redundancy within the pollinator network showed the greatest
sensitivity to landscape change. We hypothesize that declines in
hummingbird availability, diversity, and functional traits are important
mechanisms driving the observed pollen limitation of ornithophilous
flowers in fragmented tropical landscapes. Efforts to conserve large
forest patches and enhance matrix permeability are critical for
maintaining forest hummingbird communities and pollination services under
current and predicted deforestation regimes.