Taxonomy and etymology
There is some disagreement among ornithologists as to where the wallcreeper belongs in the taxonomic order. Initially, Linnaeus put it in the family Certhiidae, with the treecreepers. The wallcreeper is placed in a monotypic family Tichodromadidae by, amongst others, Clements 2007, while other authorities such as Dickinson 2003 put it in the monotypic Tichodromadinae, a subfamily of the nuthatch family Sittidae. In either case, it is very closely related to the nuthatches.
There are two subspecies of wallcreeper:
- T. m. muraria
- T. m. nipalensis is found from Turkmenistan east. It is slightly darker than the nominate race.
The wallcreeper is a 15.5–17 centimetres (6.1–6.7 in) long bird, with a mass of 17–19 grams (0.60–0.67 oz). Its plumage is primarily blue-grey, with darker flight and tail feathers. Its most striking plumage feature, though, are its extraordinary crimson wings. Largely hidden when the wings are folded, this bright coloring covers most of the covert feathers, and the basal half of the primaries and secondaries.
Distribution and habitat
A bird of the high mountains, the wallcreeper breeds at elevations ranging between 1,000–3,000 metres (3,300–9,800 ft). It is largely resident across its range, but is known to move to lower elevations in winter, when it is occasionally found on buildings and in quarries. Birds have wintered as far afield as England and the Netherlands, where one spent two consecutive winters between 1989 and 1991 at the Vrije Universiteit in Amsterdam. The species is resident across much of the Himalayas, ranging across India, Nepal, Bhutan and parts of Tibet.
Behaviour and ecology
This species can be quite tame, but is often surprisingly difficult to see on mountain faces. While it may be confiding in the breeding and non-breeding seasons, and vagrant birds especially are extremely tame, they will still hide when they are aware of being watched, and will hesitate before entering the nest and even take roundabout routes towards the nest during prolonged observations.
Wallcreepers are territorial, and pairs vigorously defend their breeding territory during the summer. During the winter the wallcreeper is solitary, with males and females defending individual feeding territories. The size of these feeding territories is hard to estimate but may comprise a single large quarry or rock massif; or, alternatively, a series of smaller quarries and rock faces. Wallcreepers may travel some distances from roosting sites to feeding territories. They have also been demonstrated showing site fidelity to winter feeding territories in consecutive years.
The wallcreeper is an insectivore, feeding on terrestrial invertebrates—primarily insects and spiders—gleaned from rock faces. It sometimes also chases flying insects in short sallies from a rock wall perch. Feeding birds move across a cliff face in short flights and quick hops, often with their wings partially spread.
The female wallcreeper builds a cup nest of grass and moss, sheltered deep in a rock crevice, hole or cave. The nest is lined with softer materials, often including feathers or wool, and typically has two entrances. The female usually lays 4–5 eggs, though clutches as small as three have been found. The white eggs measure 21 mm long, and are marked with a small number of black or reddish-brown speckles. Once her entire clutch has been laid, the female incubates the eggs for 19–20 days, until they hatch. During incubation, she is regularly fed by her mate. Young are altricial, which means they are blind, featherless and helpless at birth. Both parents feed the nestlings for a period of 28–30 days, until the young birds fledge. Each pair raises a single brood a year.
Though largely silent, both male and female wallcreepers sing, the females generally only while defending feeding territories in the winter. The song is a high-pitched, drawn-out whistle, with notes that alternately rise and fall. During the breeding season, the male sings while perched or climbing.
Tichodroma capeki (Late Miocene of Polgardi, Hungary) 
- BirdLife International (2012). "Tichodroma muraria". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- Campbell, Bruce; Elizabeth Lack. A Dictionary of Birds. Calton: T & A D Poyser. pp. 638–39. ISBN 0-85661-039-9.
- Tichodroma muraria on Avibase
- Svensson, Lars; Peter J. Grant (1999). Collins Bird Guide. London: HarperCollins. pp. 324–5.
- waarneming.nl (in Dutch)
- Harrap, Simon (2008), "Family Tichodromidae (Wallcreeper)", in del Hoyo, Josep; Elliott, Andrew; Christie, David, Handbook of the Birds of the World. Volume 13, Penduline-tits to Shrikes, Barcelona: Lynx Edicions, pp. 146–165, ISBN 978-84-96553-45-3
- Ehrlich, Paul R.; David S. Dobkin, Darryl Wheye & Stuart L. Pimm (1994). The Birdwatcher's Handbook. Oxford University Press. p. 440. ISBN 978-0198584070.
- Kessler, E. 2013. Neogene songbirds (Aves, Passeriformes) from Hungary. – Hantkeniana, Budapest, 2013, 8: 37-149.
- Clements, James F. (2007) The Clements Checklist of Birds of the World sixth edition
- Dickinson, Edward C. (ed) 2003 The Howard and Moore Complete Checklist of the Birds of the World third edition
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- Tichodroma muraria in the Flickr: Field Guide Birds of the World
- An itinerary in the Pyrenees of Spain to observe the wallcreeper
- Neveu Frank, Salamandre Films. (ed) 2013. Like a butterfly - The incredible life of the wallcreeper