Food resources play an important role in the
regulation of animals’ physiology and behavior. We
investigated the effect of short-term food restriction
on metabolic thermogenesis of Chinese bulbuls
(
Pycnonotus sinensis
) by measuring changes in
body mass, body fat, basic metabolic rate (BMR),
and organ mass of wild-caught Chinese bulbuls from
Wenzhou, China. Short-term food restriction induced
a significant decrease in body mass and body fat but
body mass returned to normal levels soon after food
was no longer restricted. Food restriction caused a
significant reduction in BMR after 7 days (
P<0.05),
which returned to normal levels after food restriction
ceased. Log total BMR was positively correlated with
log body mass (
r2=0.126,
P<0.05). The dry masses
of livers and the digestive tract were higher in birds
that had been subject to temporary food restriction
than in control birds and those subject to continual
food restriction (
P<0.001 and
P<0.05, respectively).
There was also significant differences in the dry mass
of the lungs (
P<0.05), heart (
P<0.01), and spleen
(
P<0.05) in birds subject to short-term food restriction
compared to control birds and those subject to
continual food restriction. BMR was positively
correlated with body and organ (heart, kidney and
stomach) mass. These results suggest that the
Chinese bulbul adjusts to restricted food availability by
utilizing its energy reserves, lowering its BMR and
changing the weight of various internal organs so as to
balance total energy requirements. These may all be
survival strategies that allow birds to cope with
unpredictable variation in food abundance.
