Nuthatch © Richard Steel
Despite their sedentary nature, Nuthatches were found in winter in an extra 37 tetrads without a breeding season record: 407 tetrads had birds in both seasons, 87 with winter presence only, and there were 50 tetrads in which they were found in the breeding season but not in winter. The areas occupied in winter include parts of the Gowy valley and the south-central Cheshire band without breeding season presence, and odd tetrads in the northern parts of Wirral, Halton and Warrington, but these mostly remain blank. It is not clear, however, how much of this is from birds moving in to these areas and what might be attributed to Nuthatches becoming easier to record through visiting gardens: ‘human’ habitats made up 14% of the submitted habitat codes in the breeding season but 25% of the total in winter, with a corresponding drop in the proportion of woodland records. They can be quite inconspicuous on some winter days, but on others, many birds seem to be calling and they are just as easy to detect as they are in spring.
Nuthatches are extremely territorial birds, with some birds starting to establish territories as early as June, as little as two weeks after they fledge (Matthysen 1998)! It is not surprising that the Atlas database shows that 90% of the 376 records where surveyors submitted a count were of one or two birds only, with most of the others, up to a maximum of eight in Delamere Forest (SJ57K), at well-stocked feeding stations. Most territories are established by early autumn, with little exploration by November and December, followed by resurgence in spring, not least because most of the winter deaths occur in late winter and spring, as the food remaining from the autumn crop reaches a minimum (BTO Winter Atlas). Pairs usually remain together and defend their breeding territory in winter as well as during the breeding season. Juveniles disperse as far as they have to in order to find a suitable territory, although they usually try to fit in to a vacant area near their natal site. In my study of the Delamere Forest population, with more than 500 captures, I have had two instances of birds ringed as chicks moving 1.3 km to a prime territory, both of them males, but that is a long way for a Nuthatch and every other bird has been retrapped at the site where it was ringed. The national database shows that the median distance of movement, for both sexes, is less than 1 km (Migration Atlas).
Their winter diet comprises live food when they can find it, especially insects hidden in or under bark, but is mainly vegetarian, especially seeds of trees – hazel, beech, oak (acorns), hornbeam, sycamore, yew and ash – which they often open by wedging them in a tree and hammering on the nut, behaviour that gains them their English name. They readily supplement these natural foods with human-provided fare, mainly peanuts. In times of plenty, Nuthatches store food in caches, mainly tree-crevices, birds usually covering their food with a piece of bark, lichen or moss for retrieval at a later date.
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