Effects of photoperiod on memory and food storing in captive marsh tits, Parus palustris

Field observations of food storing in several species of birds indicate that this behaviour pattern varies seasonally. Storing can be experimentally manipulated in captive birds by altering photoperiod and temperature. The objective of this study was to determine whether photoperiod manipulations affected spatial memory in a food-storing bird, the marsh tit, Parus palustris. One treatment group received a photoperiod of decreasing daylength (simulated autumn) in August, followed by a period of short days (simulated winter) in September and early October, and a sudden onset of long-day photoperiods (simulated summer) in mid-October. The other group was held on long days until mid-October and then suddenly exposed to short days. Results indicate that differences in photoperiod between treatment groups caused differences in storing behaviour and spatial memory. Birds experiencing short days after an accelerated autumn performed better on a test of spatial memory than those maintained on long days. After the photoperiod regimes were switched between treatment groups, this difference disappeared. On a similar spatial memory test in which subjects could rely only on non-spatial cues (e.g. colour), there were no differences between treatment groups, regardless of photoperiod, indicating that the effects of photoperiod are specific to spatial memory. (C) 1996 The Association for the Study of Animal Behaviour