The treecreeper is one of our smallest and lightest birds, weighing a mere 10g – barely heavier than a £1 coin. Despite its tiny size, it manages to live here all year round; although it does struggle to survive during cold winters, especially when a freeze occurs after a spell of wet weather.
That’s because treecreepers feed on tiny insects, which they prise out of crevices in the branches and trunks of trees. During the infamous big freeze of 1962-63, those branches and trunks were covered with glazed frosts, a thin film of ice which prevented the treecreepers from accessing their food supplies.
In contrast, during the twentieth century’s other major freeze, 1946-47, a dry spell beforehand meant that the birds still had access to insects, and so some managed to survive, despite the cold.
Like other small birds such as the wren and goldcrest, the treecreeper is benefiting from the recent spell of mostly mild winters, when freezing conditions rarely occur, especially in southern Britain. Hence its current position on the Green List, which means the species is not currently of conservation concern.
If a cold spell does occur, the usually solitary treecreepers will gather together at communal roosts in groups of up to a dozen. In the grounds of the Aigas Field Centre, in the Scottish Highlands, they often gather beneath the fibrous bark of giant sequoia trees.
