Friday, 29 August 2014

Week 60: Treecreeper ('Certhia familiaris')

The Treecreeper was @SpeciesofUK from 12th to 18th May, 2014.

The treecreeper is a wonderful, active little bird that, as its name suggests, lives in trees. It's notable for its foraging habits and slender curved bill.

[Flickr Creative Commons © gynti_46]

The treecreeper was first described by the Ancient Greeks.

While in the UK we refer to it as the 'treecreeper', elsewhere this bird is called the 'Eurasian treecreeper' or 'common treecreeper' to distinguish it from other treecreeper species.[1]

The treecreeper is in the Certhia genus alongside seven other treecreeper species. There are a further two treecreeper species in another genus.[2]

The name of the Certhia genus comes from Greek 'Kerthios', used by Aristotle to describe small tree-dwelling birds.[3]

[Flickr Creative Commons © baerchen57]

Aristotle in his 'Inquiries on Animals' described Kerthios as a small bird, bold in behaviour, living around trees, eating woodworms and finding food easily.[4]

The name 'treecreeper' itself comes, pretty obviously, from the bird's habit of creeping up trees!

[Wikimedia Commons © Pawel Kuzniar]

Regional UK names for the treecreeper include Snàgair (Gaelic), Snag (Irish) and Dringwr bach (Welsh).[5]

The treecreeper species is made of nine or more subspecies, found in different parts of its range throughout temperate Eurasia. The UK subspecies is C. f. britannica.[6]

The treecreeper spends most of its time in trees.

The treecreeper is resident in the UK and has a fairly stable population of around 200,000 breeding territories.[7] Across Europe there are between 3.7 to 7 million pairs.[8]

Pair of Treecreepers
[Flickr Creative Commons © Edwyn Anderton]

The treecreeper occurs in a variety of habitats but spends nearly all its time in trees. It's most often seen on the trunks of trees in woodland.[9]

[Flickr Creative Commons © Edwyn Anderton]

Treecreepers will visit gardens if you've got a suitable mature tree. They can be tempted in during winter by fat, smeared onto the trunk.[10]

Treecreepers leave their breeding territories in autumn and winter and often join mixed flocks of other small birds such as tits.[11]

Although they are more mobile during winter, treecreepers will rarely stray more than 20km from their breeding territory.[12]

Treecreepers are surprisingly small.

Treecreepers are small, verging on tiny - only about the size of a wren, although they appear larger because of their long bill and tail.[13]

[Flickr Creative Commons © Sergey Yeliseev]

A common description of the treecreeper is 'mouse-like,' because of their size and colour but also because of how they seem to scuttle up tree trunks.[14]

The treecreeper is basically brown above and white below. It has mottled white markings on its wings and back.[15]

[Flickr Creative Commons © Sergey Yeliseev]

The intricately mottled plumage provides ideal camouflage for treecreepers while they're on tree trunks.[16]

Treecreeper Camouflage
[Flickr Creative Commons © Sergey Yeliseev]

Treecreepers have a long white stripe above the eye, the 'supercilium', a characteristic of many other bird species such as warblers.[17]

Treecreeper - White Supercilium
[Flickr Creative Commons © Mark Kilner]

The treecreeper has an extremely distinctive, long and slender, down-curved bill.[18]

Treecreeper - Down-curved Bill
[Flickr Creative Commons © Sergey Yeliseev]

Our treecreeper has a close European cousin.

In Europe there is another treecreeper species, the 'short-toed treecreeper', which is very similar to the treecreeper although the song is different.[19]

Short-toed Treecreeper
[Flickr Creative Commons © Isidro Vila Verde]

The short-toed treecreeper does actually breed in the Channel Islands and occurs in the UK as a vagrant. It's probably under-recorded here because it’s often mistaken for a common treecreeper.[20]

The foraging habits of the treecreeper are very distinctive.

Treecreepers mainly eat insects and spiders hidden in crevices in bark. They work in a spiral around a tree trunk, scuttling upwards.[21]

The treecreeper will progress up a trunk in a series of short bursts/jerks, now and then making a sideways hop to explore a promising crevice.[22]

Once a treecreeper has located a gap in the bark it pushes its scimitar-like bill into the crack and delicately removes its quarry.[23]

If it reaches a branch on its way up the treecreeper will travel outwards clinging on beneath it, perfectly happy upside-down.[24]
After a short while, the treecreeper will fly to another nearby tree and repeat the process.[25]

Treecreeper with a Grub
[Flickr Creative Commons © Sergey Yeliseev]

Treecreepers are vulnerable in cold weather if their food gets sealed into the trunks by frost, especially in more exposed woodland.[26]

During the winter, treecreepers can increase their chances of survival by adding pine/spruce seeds to their diet.[27]

Treecreeper nests are well-hidden.

Treecreepers nest in a constricted space, often a small bed of twigs behind a piece of hanging bark with two openings, an entrance and exit.[28]

Treecreeper Emerging from Nest
[Flickr Creative Commons © Edwyn Anderton]

Treecreeper nesting is timed to take advantage of the glut of caterpillars at the beginning of June. They occasionally produce a second brood.[29]

The treecreeper clutch size is five to six eggs which they incubate for thirteen to seventeen days. The chicks fledge after fifteen to seventeen days.[30]

Treecreepers start breeding the year after they are born. They typically live for two years but the oldest recorded was eight.[31]

Strange but true…

Unlike the nuthatch, the treecreeper can’t climb down trees head first. It has to hop down backwards due to its tail getting in the way.[32]

As a result a bird seen scuttling up a tree is almost always a treecreeper. A bird scuttling down a tree is probably a nuthatch.[33]

[Flickr Creative Commons © Sergey Yeliseev]


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