| Ground tit | |
|---|---|
 | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Family: | Paridae |
| Genus: | Pseudopodoces Zarudny &Loudon, 1902 |
| Species: | P. humilis |
| Binomial name | |
| Pseudopodoces humilis (Hume, 1871) | |
 | |
| Distribution | |
| Synonyms | |
Podoces humilisHume, 1871 | |
Theground tit,Tibetan ground-tit orHume's ground-tit (Pseudopodoces humilis) is abird of the Tibetan plateau north of theHimalayas. The peculiar appearance confused ornithologists in the past who called it asHume's groundpecker and still later asHume's ground jay orTibetan ground jay assuming that it belonged to thefamilyCorvidae that includes the crows and jays. Although morphologically confusing, thespecies has since been identified using molecular sequence comparisons as being a member of thetit family (Paridae) and is the only species in thegenusPseudopodoces.[2] It is found in the Tibetan Plateau of China, India, Nepal & Bhutan.
Pseudopodoces is somewhat similar in appearance to the unrelatedground jays (Podoces) but much smaller – about the size of ahouse sparrow (Passer domesticus) – and lacks any conspicuous markings. More strongly however, it resembles awheatear (Oenanthe) inhabitus, but lacks black feathers and has a strong and slightly downcurved bill resembling that of achough (Pyrrhocorax) in shape (though not in colour). Its soft, lax bodyplumage is extremelycryptic in its naturalhabitat. The underside is a greyish-fawn in colour, with atawny hue. The upper parts are mostly a darker fawn-brown, with the centralrectrices and the primaryremiges a little darker still; the head is colored like the underside, with a darker cap and light nape patch, somewhat reminiscent of sometits and chickadees, especially those from thegeneraParus sensu stricto andPeriparus. The bill, legs and feet are black. Males and females look alike.[3][4]
The voice is described as a plaintive whistling,cheep-cheep-cheep-cheep and it also has a two syllablefinch-like call.[5]
| Phylogeny of the Paridae with the position ofPseudopodoces highlighted[6] |
The ground tit was traditionally considered a relative of theground jays (Podoces), based on its voice and habits. Itsautapomorphies have certainly puzzled 20th centuryornithologists, but due to its remote range and nondescript appearance, it was little studied and not suspected to be anything but an aberrant ground jay for more than 100 years after its description by Hume.[7] In 1978[8] and 1989[9] however, two studies of itsanatomy determined that – although at that time unassignable to anyfamily due to its peculiar adaptations, it appeared that it was not a corvid but a more advanced songbird of theinfraorder today known asPasserida.[2]
From 2003 onwards,osteological,mtDNA andnDNAsequence and otherbiochemical data[10] has firmly allied it with the tits and chickadees (Paridae). In fact, genetic evidence suggests that it is a closer relative of thegreat tit and its relatives in the genusParus sensu stricto than the chickadees and their relatives of the genusPoecile.[11]
It occurs across theTibetan Plateau ofChina and the neighboring areas of westernSichuan andGansu. The Tibetan ground-tit inhabits openalpine steppe and sometimes morearid regions with small scattered shrubs, rarely if ever occurring lower than 3,000 metersabove sea level. It is not found anywhere where dense vegetation (especially trees) predominates. The flight of this bird is not strong and it flies low over the ground preferring to run or jump out of the way if approached which it does very quickly. It moves on the ground in unpredictable hops and bounces which can be quite long – jumps of three times the bird's length are achieved without assistance by the wings – rather than striding or running likePodoces ground jays. Observers have compared the sight of a Tibetan ground-tit moving along to a small greyish-brownrubber ball.[3]
It obtains food on the ground, eating a wide range ofarthropod prey, often obtained by probingyak (Bos grunniens) dung and turning it over to flush the prey out. It also peers into rock crevices and into holes in the ground in its search for food. Individuals have been observed to poke mud in and nearpuddles likehoopoes (Upupa epops); in general the bill is extensively used for digging, much like the similarly-shaped one of thered-billed chough (Pyrrhocorax pyrrhocorax). If chased by abird of prey or other predator, it will bolt straight down the nearest hole like arodent until the danger has passed. They are frequently found near colonies ofpikas (Ochotona). Though the birds and the mammals probably benefit from each other's vigilance, their association is probably less due to a strongmutualism but rather because both preferhabitat with similar ground cover andsoil.[3]
The nest is rather unusual for that of apasserine, being built inside a burrow which the birds excavate themselves. It is usually dug horizontally into a bank or wall of earth, and can reach a depth of 1.8 meters. The nest is placed at the end of this in a small chamber and consists usually just of bit of wool placed onto a grass base. The 4–6eggs are pure white and the young stay with their parents for some time after fledging; half-grown young are still fed by their parents on occasion as late as August.[12] Cooperative breeding occurs in this species, with monogamous pairs frequently having at least one male helper who are yearlings which remain on the natal territory. This behaviour is thought to occur as a result of there being a shortage of males in the population.[13]
The ground tit is not amigratory bird but may descend to lower altitudes in valleys during the winter. In addition to digging nesting burrows, ground-tits frequently dig roosting burrows to use during the coldest months.[14]
