Sparrow circadian rhythm responses to rotated light-dark schedules.
House sparrows, Passer domesticus, were individually subjected to light-dark regimens while their perching activity was continuously monitored. The sparrows resynchronized in 5 days when LD8:16 (8 hr of light alternating with 16 hr of dark) was advanced by 8 hr; however, the sparrows were 1.7 hr from resynchronization after 5 days when the schedule was delayed 8 hr. Sparrows subjected to two simultaneously presented light-dark schedules (rotated LD8:16 provided by one light source imposed together with LD12:12 provided by a second light source) did not ignore either cycle; instead the sparrows responded as to a sequence of photoperiods; they resynchronized the onsets of their activity with the first time of lights-on of the collective photoperiod provided by the two light sources.
Binkley
S
S
Biology Department, Temple University, Philadelphia, PA 19122.
Mosher
K
K
D000818:Animals; D001717:Birds / Q000502:physiology*; D002940:Circadian Rhythm; D005260:Female; D008027:Light; D008297:Male; D010507:Periodicity