Circadian rhythms in house sparrows: lighting ad lib.
House sparrows, Passer domesticus, have circadian rhythms of locomotor activity that can be entrained by light-dark cycles. Perch-hopping activity was studied in house sparrows that were given control of their own lighting. In one series of experiments, sparrows permitted to select their own lighting most commonly chose circadian freerunning cycles. The period of the selected freerunning cycles was 23.2 hr (0.9 hr shorter than the period length the sparrows exhibited in constant dark). The average self-imposed "photoperiods" in the selected freerunning cycles ranged from 8.2-10.0 hr. In a second series of experiments, sparrows were exposed to LDLD1:6:1:16. This cycle can be interpreted ambiguously as the skeleton of a short photoperiod, LD8:16, or of a long photoperiod, LD18:6. All the birds (13 birds; 23 trials) interpreted the skeleton cycle as a short photoperiod because they entrained to it as they would to LD8:16.
D000818:Animals; D001717:Birds / Q000502:physiology*; D002755:Choice Behavior / Q000502:physiology; D002940:Circadian Rhythm; D005260:Female; D008027:Light; D008297:Male; D009043:Motor Activity / Q000502:physiology