The recollection of past experiences allows us to recall what a particular event was, and where and when it occurred1,2, a form of memory that is thought to be unique to humans3. It is known, however, that food-storing birds remember the spatial location4,5,6 and contents6,7,8,9 of their caches. Furthermore, food-storing animals adapt their caching and recovery strategies to the perishability of food stores10,11,12,13, which suggests that they are sensitive to temporal factors. Here we show that scrub jays (Aphelocoma coerulescens) remember ‘when’ food items are stored by allowing them to recover perishable ‘wax worms’ (wax-moth larvae) and non-perishable peanuts which they had previously cached in visuospatially distinct sites. Jays searched preferentially for fresh wax worms, their favoured food, when allowed to recover them shortly after caching. However, they rapidly learned to avoid searching for worms after a longer interval during which the worms had decayed. The recovery preference of jays demonstrates memory of where and when particular food items were cached, thereby fulfilling the behavioural criteria for episodic-like memory in non-human animals.
This work was supported by grants from the NIH and the Whitehall Foundation toN.S.C. and from the BBSRC to A.D. We thank A. Quaglino, M. Caun, J. Greig, D. Griffiths, K. Sanford, E. Krebs and G. Krebs for their help with aspects of the experiment; E. Tulving for discussion and inspiration; and K. Britten, R. Gerlai, J. Krebs, D. Lee, P. Marler, L. Miyasato, R. Morris, K. Sanford, E.Tulving and A. Quaglino for comments on the manuscript.