Sunbirds' tendency to hover: the roles of energetic rewards, inflorescence architecture and rain - data

Although the Old World sunbirds are generally considered to be an
ecological analogue of the New World hummingbirds, it is commonly believed
that in contrast to hummingbirds, sunbirds perch while feeding.
Nevertheless, recent studies have shown that Old World nectarivores hover
while feeding more frequently than previously thought, and some Old World
plants seem to have adapted to hovering bird pollinators. To reveal the
importance of sunbird foraging behavior in nectar acquisition and to test
whether this behavior is determined by plant architecture and rain
intensity, we focused on the specialized West African pollination system
of Impatiens sakeriana and its two major pollinators, the Cameroon Sunbird
(Cyanomitra oritis) and the Northern Double-collared Sunbird (Cinnyris
reichenowi). C. oritis hovered more often than C. reichenowi while feeding
on flowers, although both species were observed hovering regularly. For
both species, hovering reduced the feeding time, but this reduction and
the consequent estimated changes in energetic intake were
species-specific. We found that both floral pedicel and peduncle length,
as well as precipitation, negatively affected the probability of C.
reichenowi hovering but did not have any significant effect on the
behavior of C. oritis. Our study demonstrates that hovering behavior is
common in the studied sunbird taxa and that plant architecture and
environmental factors can influence sunbird foraging behavior.
Nevertheless, the extent of hovering versus perching behavior, as well as
the effects of biotic and abiotic factors, is species-specific.