The aims of this study were to test whether or not Jays Garrulus gland
arius store stones and, if so, to examine the conditions under which t
hey store stones. By directly observing the behaviour of five captive
jays that were housed individually in flight cages, we found that ston
es were stored only in the absence of food items or when food items we
re no longer available to store and that there was a strong preference
for storing stones that resembled acorns in both size and appearance
(in terms of colour, shape and smoothness of the surface) and were und
amaged rather than heavily chipped. These results are discussed in ter
ms of Tinbergen's classic ethological model in which animals respond s
electively to certain key features and ignore other features of the st
imulus.