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Photoperiodic Regulation of Reproduction in Subtropical Female Yellow-Throated Sparrows (Gymnorhis xanthocollis)

P. D. Tewary and Anand S. Dixit
The Condor
Vol. 88, No. 1 (Feb., 1986), pp. 70-73
DOI: 10.2307/1367755
Stable URL: http://www.jstor.org/stable/1367755
Page Count: 4
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Photoperiodic Regulation of Reproduction in Subtropical Female Yellow-Throated Sparrows (Gymnorhis xanthocollis)
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Abstract

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.

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