Eurasian jays are omnivores and opportunistic, eating pretty much whatever they can find. Acorns represent the largest part of their diet. They crack the shell by biting it and using their beaks to lever the shell pieces open until they can get the meat out. They collect the acorns of Quercus oaks in the autumn and bury them to eat throughout the year. They rely on stored food the most from May to July, when they are feeding offspring. One bird can hide between 4500 and 11,000 acorns and will use its memory to locate caches up to ten months later. When hiding acorns, they usually hide only one in a spot, but may hide two or three acorns there. The impulse to store acorns for later use is so strong that captive jays without access to a surplus of acorns will store things that look like acorns, including properly shaped stones.
Eurasian jays prefer the acorns of Quercus ilex, Quercus suber, and Quercus faginea, but avoid acorns from Quercus coccifera. Preference is probably linked to relative nutritional value. Quercus ilex acorns have the highest fat content and Quercus coccifera acorns have the highest amount of tannins, at least of the four species studied by Pons and Pausas (2007). Eurasian jays prefer bigger acorns over smaller ones. They usually transport one acorn at a time, but they have been observed carrying up to five at once. Single acorns are carried in the bill. If more than one is carried, the first one or ones are swallowed and carried in the crop while the last, and usually largest, is held in the bill.
In addition to acorns, Eurasian jays eat fruit, grains, and nuts. They also take invertebrates, including worms, snails, slugs, and insects. Eggs are not instinctively recognized as food, but once a bird learns to crack it open and eat the insides, it will continue to do so with other eggs it encounters. They will eat small birds, their young, and their eggs. Reed warblers (Acrocephalus scirpaceus) are an example of a common prey species. Eurasian jays eat plenty of carrion. Researchers studying carrion consumers have found jays will visit about half of available carcasses, especially those in the forest. They use their feet to hold food, but not if the food is sticky. They look everywhere they can for food, including in crevices, loose bark, small holes, under leaves, or any other spot a prey item might be hiding. However, they avoid food that is on open ground instead of covered with foliage. To open something, they insert their beaks and then try to open them. To turn something over, they pull on it with their beaks or put their beaks under the edges and push sideways.
Animal Foods: birds; mammals; eggs; carrion ; insects; terrestrial non-insect arthropods; terrestrial worms
Plant Foods: seeds, grains, and nuts; fruit
Foraging Behavior: stores or caches food
Primary Diet: herbivore (Granivore ); omnivore
- Clayton, N., D. Griffiths, A. Bennett. 1994. Storage of stones by Jays (Garrulus glandarius). IBIS, 136: 331-334.
- Clayton, N., R. Mellor, A. Jackson. 1996. Seasonal patterns of food storing in the Jay Garrulus glandarius . IBIS, 138: 250-255.
- Davies, N., S. Butchart, T. Burke, N. Chaline, I. Stewart. 2003. Reed warblers guard against cuckoos and cuckoldry. Animal Behavior, 65: 285-295.
- Pons, J., J. Pausas. 2007. Not only size matters: Acorn selection by the European jay (Garrulus glandarius). Acta Oecologica, 31: 353-360.