Biochronometry of photoperiodically induced fat deposition in a migratory finch, the Blackheaded bunting (Emberiza melanocephala) (Aves) |
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Authors: | P. D. Tewary Vinod Kumar |
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Affiliation: | Department of Zoology, Banaras Hindu University, Varanasi 221 005, India |
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Abstract: | This investigation attempts to identify the mechanism(s) involved in the fat deposition in a photoperiodic migratory species, the Blackheaded bunting ( Emberiza melanocephala ). Groups of photosensitive male buntings were exposed to resonance, interrupted night, and ultra-short-day light cycles for 35, 42 and 75 days, respectively. Birds were weighed at the beginning and at the end of the experiments. Those exposed to ultra-short-day light cycles were also weighed at critical intervals during the treatment period. Our results indicate that: (a) a light-sensitive rhythm with a period of about 24 hr is involved in the photoperiodic induction of premigratory fattening and weight gain in Blackheaded buntings: (b) buntings possess a bimodal pattern 'of sensitivity to photoperiods that induce fattening, and (c) this endogenous circadian rhythm can be entrained by an ultrashort photophase of 3 h if the latter is coupled with scotophases of specific duration. |
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