Wallcreeper
Encyclopedia
The Wallcreeper is a small passerine
bird
found throughout the high mountains of Eurasia
. It is the only member of the genus
Tichodroma.
s. 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:
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.
s, the Wallcreeper breeds at elevations ranging between 1000 –. 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
.
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.
, feeding on terrestrial invertebrates—primarily insects and spider
s—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.
of grass
and moss
, sheltered deep in a rock crevice, hole or cave. The nest is lined with softer materials, often including feather
s or wool
, and typically has two entrances. The female usually lays 4–5 eggs
, though clutch
es 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.
Passerine
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...
bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
found throughout the high mountains of Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
. It is the only member of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Tichodroma.
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 treecreeperTreecreeper
The treecreepers are a family, Certhiidae, of small passerine birds, widespread in wooded regions of the Northern Hemisphere and sub-Saharan Africa. The family contains ten species in two genera, Certhia and Salpornis...
s. 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
Nuthatch
The nuthatches are a genus, Sitta, of small passerine birds belonging to the family Sittidae. Characterised by large heads, short tails, and powerful bills and feet, nuthatches advertise their territory using loud, simple songs...
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 TurkmenistanTurkmenistanTurkmenistan , formerly also known as Turkmenia is one of the Turkic states in Central Asia. Until 1991, it was a constituent republic of the Soviet Union, the Turkmen Soviet Socialist Republic . Turkmenistan is one of the six independent Turkic states...
east. It is slightly darker than the nominate race.
Description
The Wallcreeper is a 15.5 – long bird, with a mass of 17 –. Its plumagePlumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
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 mountainMountain
Image:Himalaya_annotated.jpg|thumb|right|The Himalayan mountain range with Mount Everestrect 58 14 160 49 Chomo Lonzorect 200 28 335 52 Makalurect 378 24 566 45 Mount Everestrect 188 581 920 656 Tibetan Plateaurect 250 406 340 427 Rong River...
s, the Wallcreeper breeds at elevations ranging between 1000 –. It is largely resident across its range
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...
, 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
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
, where one spent two consecutive winters between 1989 and 1991 at the Vrije Universiteit
Vrije Universiteit
The Vrije Universiteit is a university in Amsterdam, Netherlands. The Dutch name is often abbreviated as VU and in English the university uses the name "VU University". The university is located on a compact urban campus in the southern part of Amsterdam in the Buitenveldert district...
in Amsterdam
Amsterdam
Amsterdam is the largest city and the capital of the Netherlands. The current position of Amsterdam as capital city of the Kingdom of the Netherlands is governed by the constitution of August 24, 1815 and its successors. Amsterdam has a population of 783,364 within city limits, an urban population...
.
Behaviour
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.
Feeding
The Wallcreeper is an insectivoreInsectivore
An insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures. An alternate term is entomophage, which also refers to the human practice of eating insects....
, feeding on terrestrial invertebrates—primarily insects and spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
s—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.
Breeding
The female Wallcreeper builds a cup nestBird nest
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American Robin or Eurasian Blackbird, or the elaborately woven hanging nest of the...
of grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...
and moss
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
, sheltered deep in a rock crevice, hole or cave. The nest is lined with softer materials, often including feather
Feather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...
s or wool
Wool
Wool is the textile fiber obtained from sheep and certain other animals, including cashmere from goats, mohair from goats, qiviut from muskoxen, vicuña, alpaca, camel from animals in the camel family, and angora from rabbits....
, and typically has two entrances. The female usually lays 4–5 eggs
Bird egg
Bird eggs are laid by females and incubated for a time that varies according to the species; a single young hatches from each egg. Average clutch sizes range from one to about 17...
, though clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
es 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
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...
the eggs for 19–20 days, until they hatch. During incubation, she is regularly fed by her mate. Young are altricial
Altricial
Altricial, meaning "requiring nourishment", refers to a pattern of growth and development in organisms which are incapable of moving around on their own soon after hatching or being born...
, 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.