Friday, 31 March 2017

British Birds: Eurasian Nuthatch

Eurasian Nuthatch, Sitta europaea caesia
After Blue Tits and Great Tits, one of the British Birds most likely to be seen at a feeder in a garden, especially near woodland, is the Eurasian Nuthatch Sitta europaea. This species is currently doing well in the British Isles, and is currently spreading northward in Scotland, although it is currently absent from Ireland. There are at least 20 subspecies, with a range from western Europe across to China and South Korea, and southwards into the Caucasus. The form in the UK is caesia, which is also found in much of western Europe, and is typical of a group of subspecies with buff underparts and a white throat. Further east from Scandinavia across Siberia the europaea group has white underparts, and finally in China the sinensis forms have the throat and underparts pale buff.

Eurasian Nuthatch S.eurpaea europaea
Other than the Eurasian Nuthatch, there are nearly 30 other recognised species, with the family having a distribution centred in south east Asia. With the exception of the Velvet-Fronted Nuthatch Sitta frontalis,  which prefers lowland tropical forest, and the two species of Rock Nuthatch, S. neumayer and S. tephronota, which feed on bare hillsides, they are found in temperate and Arctic forests. Most are highly sedentary and remain on territory year round, although the North American Red-Breasted Nuthatch is a long distance migrant.
Velvet-Fronted Nuthatch, S.frontalis
European Nuthatches are typically birds of deciduous or mixed conifer forest. They mainly forage for insects over the trunk and branches of trees, and their foot anatomy enables them to move both up and down the trunks with ease. In this they differ from their relatives, the treecreepers, which only move up the trunks when feeding. They also take many seeds, especially in the winter, and hoard food year round. For this reason their visits to feeders are usually brief, with a bird selecting a seed, flying off to stash it in a crevice or moss on a tree trunk, and then returning. Being quite territorial there is usually only one or two birds visiting a given feeder at a time.
Western Rock Nuthatch, S.neumayer
Nuthatches are hole-nesters, and mostly use old woodpecker holes of a suitable size. They will modify the size of the entrance hole with mud to reduce the size of the entrance, and the nest cavity is lined with bark fragments. Nest construction is by the female and can take up to four weeks. The clutch can be up to 9 eggs. Incubation takes up to 18 days, and the young fledge after around three weeks, with the young dependent on the parents for another two before dispersing. Average lifespan in the wild is two years, but the record for a wild bird in the UK is twelve.

The natural predators of Nuthatches are typical for small woodland birds. The main threat is the Sparrowhawk, but Tawny Owls and even Goshawks take some. At the nest the main threat is raids by Great Spotted Woodpecker, with Weasels also a potential problem. Given the vast range the status is Least Concern, although local deforestation may threaten some small isolated populations.

Images of Eurasian Nuhtatch are mine, others from wikipedia

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