By Charlotte Owen
The common holly Ilex aquifolium is a plant that everyone will recognise, with its glossy evergreen leaves and vibrant red berries. It has been a symbol of midwinter festivals for many centuries and as Christmas approaches, there’s a good chance that you’ve already brought some inside to ‘deck the halls’ or make a festive wreath, carefully selecting the stems with the best displays of berries. Please don’t forget that the berries are toxic to humans so if you have small children make sure they can’t reach them.
These brilliant berries are just as popular with wildlife and they can be an important source of winter food for birds. Only the female holly trees produce berries, which develop from tiny white flowers and mature by late November. The berries are bitter at first but become more palatable after the first frosts have softened them – and it’s when the ground is frozen that many birds will rely on berries to see them through.
The robin is most famously associated with holly and, while it may remain the king of the Christmas cards, in the garden it must compete with a wide range of other berry-loving species including the blackbird and song thrush. More exotic visitors to the berry buffet include the redwing and fieldfare, which come here to escape the much harsher winter conditions in their northern breeding grounds. They often flock together in their search for food and may visit gardens in particularly harsh or snowy conditions.
But perhaps the robin’s strongest competitor is the mistle thrush. These birds feed in flocks until the holly berries mature, when they set off alone or in pairs to find a tree bursting with berries and claim it as their own personal larder. They will defend it vigorously from all intruders, just in case other food sources become so scarce that they need to rely on their berries as a backup. This means that they may not actually eat any of their berries but they will make sure that nobody else eats them either - so if you see a holly tree still full of berries when most others are bare, you’re probably under the watchful gaze of its mistle thrush guardian.