Jay
Garrulus glandarius
UK Conservation status: GREEN
Autumn is when you are most likely to see a jay.
Jays are shy woodland birds, rarely moving far from cover which makes them quite difficult to see even though they are very colourful. Unlike other members of the crow family, jays do not form large flocks. Even the two members of an established pair seem to spend relatively little time together, although they will work together to defend their breeding territory.
A jay typically has a lifespan of four years, some may survive for as long as 15 years. They usually first breed when two years old. Jays lay only one clutch a year with five to six eggs. Both birds construct the nest and feed their young. The chicks are largely fed on leaf-eating caterpillars which are mainly collected from the foliage of oak trees.
Photograph by Marilyn Peterkin.
Jays are famous for their acorn feeding habits and in the autumn you may see them burying acorns for retrieving later. Individuals collect and store several thousand acorns – as many as 8,000 - mainly in October. This hoarding behaviour allows them to live off acorns right through the winter until early summer. They are however also opportunistic hunters and will take insects, chicks from other birds’ nests and small mammals.
Jays collect one or more acorns per hoarding trip. How is this done? The first ones are swallowed and the last one is usually carried in the bill. They can carry up to six acorns in this way. Jays spread their acorns widely and when carrying several acorns these are generally buried at different sites, hidden in the cracks and crevices of trees or buried. When burying the jay will push acorns into the soil, hammer them in deeper, and then cover to hide their store from other animals.
Jays have an amazing ability to recall the location of their hoarded acorns – a spectacular feat if you have buried thousands! It is also known that in summer they can use the presence of a newly germinated oak seedling to reveal the acorn at its base. The jay pulls at the stem of seedling and then removes and eats the two cotyledons (which contain a store of food to fuel the developing seedling). Remarkably, despite being sabotaged in this way by a jay, many oak seedlings are not damaged severely.
Jays and Oaks
Many of the hoarded acorns germinate and become seedlings so that jays play an important role in the dispersal of acorns and the reproduction of oaks. The spread of young oak trees across the Croft Close Set-aside from a few oaks in the boundary hedges shows the importance of jays in creating what we see today from an abandoned arable field.
The two species, oak and jay, need each other, both benefit from the relationship – this is an example of a symbiotic relationship of which there are many in nature.