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Science 22 May 1959:
Vol. 129. no. 3360, pp. 1425 - 1426
DOI: 10.1126/science.129.3360.1425
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Articles

Role of Light in the Photoperiodic Responses of Migratory Birds

ALBERT WOLFSON 1

1 Department of Biological Sciences, Northwestern University, Evanston, Illinois

Light-dark cycles with 12-hour and 16-hour photoperiods are known to be effective in 24-hour cycles in inducing gonadal activity and fat deposition in migratory birds. Twenty-four-hour cycles with 16-hour dark periods are not effective. To test the role of the light periods and the dark periods in a given cycle, slate-colored juncos were subjected to light in cycles which combined stimulatory photoperiods (L) and inhibitory dark periods (D) as follows: 12L-16D; 12L-20D; 16L-16D; 16L-22D; 16L-32D. The results indicate that the photoperiod, not the dark period, determined the response.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Some Aspects of Animal Photoperiodism.
A. D. Lees (1960)
Cold Spring Harb Symp Quant Biol 25, 261-268
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Science. ISSN 0036-8075 (print), 1095-9203 (online)