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Photoperiodic Regulation of Reproduction in Subtropical Female Yellow-Throated Sparrows (Gymnorhis xanthocollis)
P. D. Tewary and Anand S. Dixit
Vol. 88, No. 1 (Feb., 1986), pp. 70-73
Published by: Cooper Ornithological Society
Stable URL: http://www.jstor.org/stable/1367755
Page Count: 4
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Ovarian development followed by regression occurred in Yellow-throated Sparrows (Gymnorhis xanthocollis) that were kept on short daily photoperiods of 8 hr (8L:16D) for eight weeks and were then exposed to long days (15L:9D). No ovarian growth occurred if they were kept on 8L:16D. This species did not exhibit ovarian growth on normal day lengths at Varanasi, India, until they experienced the increasing day lengths of summer. When Yellow-throated Sparrows were exposed to photoperiods between 6-20 hr/day for 35 days, ovarian growth did not occur unless day length was 12 or more hr/day. Our results indicate that female Yellow-throated Sparrows are photoperiodic and that annual changes in day length are responsible for ovariogenesis. Photoperiod is not apparently responsible for seasonal changes in body weight in this species.
The Condor © 1986 Cooper Ornithological Society