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| Providing hummingbirds with artificial feeders
containing sugar solution is common practice throughout
the Americas. Although feeders can affect hummingbird
foraging behavior and abundance, it is poorly understood
how far this effect may extend. Moreover, it remains
debated whether nectar-feeders have a negative impact on
hummingbird-pollinated plants by reducing flower visitation
rates and pollen transfer close to the feeders. Here, we
investigated the effects of distance to nectar-feeders on a
local hummingbird assemblage and the pollination of
Psychotria nuda (Rubiaceae), a hummingbird-pollinated
plant endemic to the Brazilian Atlantic Rainforest. At
increasing distance (0–1000 m) from a feeding-station,
where hummingbirds have been fed continuously for the
past 13 years, we quantified hummingbird abundance, and
rates of flower visitation and pollen deposition on P. nuda.
We found that hummingbird abundance was unrelated to
distance from the feeders beyond ca. 75 m, but increased
steeply closer to the feeders; the only exception was the
small hummingbird Phaethornis ruber, which remained
absent from the feeders. Plants of P. nuda within ca.125 m
from the feeders received increasingly more visits, coinciding
with the higher hummingbird abundance, whereas
visitation rate beyond 125 m showed no distance-related
trend. Despite this, pollen deposition was not associated
with distance from the feeders. Our findings illustrate that
artificial nectar-feeders may locally increase hummingbird
abundance, and possibly affect species composition and
pollination redundancy, without necessarily having a disruptive
effect on pollination services and plants’ reproductive
fitness. This may apply not only to hummingbirds,
but also to other animal pollinators. | |
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