Journal of Environmental Biology

Effect of complete and skeleton photoperiods in baya weaver, Ploceus philippinus

 

?Sanjay Kumar Bhardwaj, D. K. Sharma and Anushi

Department of Zoology, Chaudhary Charan Singh University, Meerut-250 004, India

 

(Received: 13 September, 2004 ; Accepted: 2 June, 2005)

 

 

Abstract: A study was performed to investigate the effects of complete and skeleton photoperiods on gonadal stimulation in baya weaver, Ploceus philippinus. In August 2003, five groups of acclimatized birds (n= 7 each) were exposed to 6L: 13D: 1L: 4D, 6L:6D: 1L: 11D, 11L: 13D and 13L: 11D. Birds were refractory and their exposure to 6L:13D:1L:4D, 6L:6D:1L:11D, 11L:13D and 13L:11D did not evoke any response. This clearly indicates that the birds were insensitive to the stimulatory effects of these photoperiods and perceived them as short days. An attempt was made to test the responsivity by subjecting all these groups to long day exposure after 16 weeks of experiment. Under 16L: 8D, birds did not show a response during the first 4 weeks of exposure (week 16 to week 20), but thereafter there was a significant photoinduction except 11L:13D (week 24), but the rate and magnitude was different. Until the end of the experiment (32 weeks), all groups of birds had maximum testicular volume except 11L:13D. Birds pre-exposed to 6L:13D:1L:4D, 6L:6D:1L:11D, 11L:13D and 13L:11D responded to 16L:8D, which suggests that these photoperiods helped the birds in recovering their? photosensitivity. The results from this experiment indicate that baya weaver interprets a light period depending when the light falls relative to its endogenous circadian system.

 

Key words: Photoperiod, Skeleton, Body mass, Testis, Baya weaver.

Copyright ? 2006 Triveni Enterprises. All rights reserved. No part of the Journal can be reproduced in any form without prior permission. Responsibility regarding the authenticity of the data, and the acceptability of the conclusions enforced or derived, rest completely with the author(s).