EFFECTS OF SEASON AND PHOTOPERIOD ON FOOD STORING BY BLACK-CAPPED CHICKADEES, PARUS-ATRICAPILLUS

The effects of season and photoperiod on food storing by black-capped chickadees were examined in two experiments. Chickadees were captured in March (experiment 1) or November (experiment 2), and food storing w as tested regularly in the birds' home cages. In both experiments, two groups were matched for initial level of food storing. The long-day g roup was then exposed to a summer photoperiod (16:8 h light:dark cycle ) and the short-day group to a winter photoperiod (LD 8:16 h) for 2-3 months, followed by 2-3 months in identical conditions for both groups . Birds in experiment 1 stored very little at first, but those maintai ned on long days moulted and began to store after 6-8 weeks; the group maintained on short days eventually increased storing as well. Birds in experiment 2 began by storing about three times as much food as tho se in experiment 1; storing declined over time in both groups and was not affected by photoperiod. The results suggest that food storing in parids is controlled by photoperiod in a similar way to other annually varying behaviour patterns such as breeding and migration in birds.