Ireland's Biodiversity Awareness Campaign


During autumn, mammals prepare for the cold winter months when food may become scarce. Most of them will put on fat as a food store and for insulation and many mammals will become less active.


Red Squirrel

Squirrels do not hibernate during the winter but store up extra food in hiding places in the ground. Over the autumn, Red and Grey squirrels build nests in trees called ‘dreys’with twigs and bark lined with leaves and grass. As the weather gets colder the squirrels will spend more time in their nests and will eat their hoarded acorns.

Red Squirrel Taken by Stephen Gee

Red squirrels have a long breeding season, from February to August, and in good years two litters, each typically with 3 young may be born.



In October or November, hedgehogs start to search for quiet places to hibernate, making nests using leaves and grass. Gardeners should welcome hedgehogs into their gardens as they feed on snails and slugs, many of which eat garden plants. It is important not to disturb hedgehogs during hibernation as they waste energy when they are disturbed and can die from stress.

Grey Seals

Grey seals can be seen onshore in large colonies from late August to September. Male seals (bulls) come ashore, as this time of year is the start of the mating season, while female seals (cows) come ashore to give birth. The seals congregate in large colonies on rocky shores and sandbanks, often returning to the same breeding grounds each year. Look out for newborn seal pups, born with creamy white fur which in about a month gets replaced by dense fawn-coloured adult fur. Seals should not be disturbed when they have young pups as are very sensitive and may abandon their young if they feel threatened.

©2007 Department of the Environment, Heritage and Local Government