Is bigger always better? : neither body size nor aggressive behavior predicts specialization of hummingbirds in a rocky outcrop.
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Date
2022
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Abstract
Interspecific competition can strongly influence community structure and shape
niche breadth and overlap. One of the main factors that determines hummingbird
community structure is competition for food. Hummingbirds’ functional attributes,
such as beak length and body mass, influence nectar acquisition in flowers. This
study evaluates how functional and behavioral attributes of hummingbirds influence
their specialization, as measured by pollen transportation. We tested the following
hypothesis: H1) smaller and short-billed hummingbirds will carry higher pollen
richness and relatively more pollen grains than long-billed hummingbirds; H2)
dominant and territorial hummingbirds carry a lower richness of pollen types and
fewer pollen grains when compared to subordinate hummingbirds, and H3) the
similarity in the composition of pollen morphotypes, between the hummingbirds
species, will be low because we expect to find high specialization in the use of
plant species. We conducted the study between September 2018 and March 2019
in a Campo Rupestre (rocky outcrops) in Southeastern Brazil. Hummingbirds were
captured with a trap. The pollen adhered to the body parts was collected, counted,
and identified in the laboratory. We recorded hummingbirds’ beak sizes and body
masses. Behavioral responses of hummingbirds to artificial feeders were collected
regarding the time and duration of each visit and the outcome of aggressive inter-
actions. An interaction network was built based on the pollen grains found on each
hummingbird. Our results showed that neither body size nor aggressive behaviors
influenced pollen richness on hummingbirds’ bodies. Beak length was the most
important hummingbird attribute that influenced pollen richness, but not pollen relative abundance. Short-billed hummingbirds carried the greatest richness of pollen
grains. The hummingbird pollen-grain interaction network was generalized in the
pollen grains transported. We conclude that hummingbirds’ beak length is the cen-
tral morphological variable related to pollen grain transport in rocky outcrops.
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Keywords
Interaction network, Pollen transportation, Territorial behavior, Trochilidae, Nectar acquisition
Citation
CLAUDINO, R. M. et al. Is bigger always better?: neither body size nor aggressive behavior predicts specialization of hummingbirds in a rocky outcrop. Journal of Zoology, v. 317, 2022. Disponível em: <https://zslpublications.onlinelibrary.wiley.com/doi/full/10.1111/jzo.12961>. Acesso em: 29 abr. 2022.