Environmental cues play important roles in the
regulation of an animal’s physiology and behavior.
One such cue, photoperiod, plays an important role
in the seasonal acclimatization of birds. It has been
demonstrated that an animal’s body mass, basal
metabolic rate (BMR), and energy intake, are all
affected by photoperiod. The present study was
designed to examine photoperiod induced changes
in the body mass, metabolism and metabolic organs
of the silky starling,
Sturnus sericeus
. Captive silky
starlings increased their body mass and BMR
during four weeks of acclimation to a short
photoperiod. Birds acclimated to a short photoperiod
also increased the mass of certain organs (liver,
gizzard and small intestine), and both gross energy
intake (GEI) and digestible energy intake (DEI),
relative to those acclimated to a long photoperiod.
Furthermore, BMR was positively correlated with
body mass, liver mass, GEI and DEI. These results
suggest that silky starlings increase metabolic
thermogenesis when exposed to a short photoperiod
by increasing their body and metabolic organ mass,
and their GEI and DEI. These findings support the
hypothesis that bird species from temperate climates
typically display high phenotypic flexibility in
thermogenic capacity.
