Data from: Effects of hummingbird morphology on specialization in pollination networks vary with resource availability

Specialization of species in interaction networks influences network
stability and ecosystem functioning. Spatial and temporal variation in
resource availability may provide insight into how ecological factors,
such as resource abundance, and evolutionary factors, such as
phylogenetically conserved morphological traits, influence specialization
within mutualistic networks. We used independent measures of hummingbird
abundance and resources (nectar), information on hummingbird traits and
plant–hummingbird interactions to examine how resource availability and
species' morphology influence the specialization of hummingbirds in
three habitat types (forest, shrubs, cattle ranch) sampled over 10
sessions across two years in the southern Andes of Ecuador. Specialization
of hummingbird species in the networks was measured by three indices:
d' (related to niche partitioning), generality (related to niche
width) and PSI (related to pollination services). Specialization indices
d', generality and PSI of hummingbird species were influenced by
resource availability. All indices indicated that specialization of
hummingbirds increased when the availability of resources decreased.
Variation in d' was also explained by an interaction between resource
availability and bill length; hummingbirds with a long bill switched from
being more specialized than other species when resource availability was
low to being similarly specialized when availability was high. Overall,
our results highlight the importance of ecological and evolutionary
factors determining the specialization of species in interaction networks.
We demonstrate in particular that ecological gradients in resource
availability cause substantial changes in consumers' foraging
behavior contingent on their morphology. Changes in pollinator
specialization along resource gradients can have impacts on ecosystem
functions, such as pollination by animals.