Cyanistes caeruleus (Photo: Luc Viatour)
Parus caeruleus (Linnaeus, 1758)
* Parus caeruleus
* Systema Naturae ed.10
The Blue Tit, Cyanistes caeruleus, is a 10.5 to 12 cm (4.2 to 4.8 inches,) long passerine bird in the tit family Paridae. It is a widespread and common resident breeder throughout temperate and subarctic Europe and western Asia in deciduous or mixed woodlands. It is a resident bird; i.e., most birds do not migrate.
This species was first described by Linnaeus in his Systema naturae in 1758 as Parus caeruleus.
Most authorities retain Cyanistes as a subgenus of Parus, but the British Ornithologists' Union treats Cyanistes as a distinct genus. This is supported by mtDNA cytochrome b sequence analysis which suggests that Cyanistes is not only distinct, but not close to other tits (Gill et al., 2005).
* C. c. caeruleus (Linnaeus, 1758), the nominate subspecies, occurring in Continental Europe to n Spain, Sicily, n Turkey and n Urals
The two traditional subspecies found in the Canary Islands (teneriffae) and northwest Africa from northern Morocco to northern Libya (ultramarinus) are distinctive. The Canary Islands subspecies has a black cap, and the African form has a blue back. Research is underway to split these populations into distinct species, with a peculiar "leapfrog" distribution (Kvist et al., 2005; Kvist, 2006; Sangster, 2006):
* Afrocanarian Blue Tit or Ultramarine Tit, Parus ultramarinus Bonaparte, 1841 (La Palma, Hierro, Fuerteventura, Lanzarote, NW Africa) updated to species status in 2010
The former would contain three or four subspecies (palmensis, ombriosus and ultramarinus/degener), the latter the nominate P. t. teneriffae and the unnamed distinct form of Gran Canaria.
Pleske's Tit (Cyanistes × pleskei) is a not uncommon hybrid between this species and the Azure Tit in western Russia.
This is a common and popular European garden bird, due to its perky acrobatic performances when feeding on nuts or suet. It swings beneath the holder, calling tee, tee, tee or a scolding churr".
The song period lasts almost all the year round, but is most often heard during February to June.
It will nest in any suitable hole in a tree, wall, or stump, or an artificial nest box, often competing with House Sparrows or Great Tits for the site. Few birds more readily accept the shelter of a nesting box; the same hole is returned to year after year, and when one pair dies another takes possession. It is estimated by the RSPB that there are 3,535,000 breeding pairs in the UK.
The bird is a close sitter, hissing and biting at an intruding finger. In the South West of England such behaviour has earned the Blue Tit the colloquial nickname "Little Billy Biter". When protecting its eggs it raises its crest, but this is a sign of excitement rather than anger, for it is also elevated during nuptial display. The nesting material is usually moss, wool, hair and feathers, and the eggs are laid in April or May. The number in the clutch is often very large, but seven or eight are normal, and bigger clutches are usually laid by two or even more hens. It is not unusual for a single bird to feed the chicks in the nest at a rate of one feed every ninety (90) seconds during the height of the breeding season. Its colourful mix of blue, yellow, white and green make the blue tit one of the most attractive resident garden birds. Almost any garden with a peanut feeder will attract them and they readily breed in nestboxes. In winter they form flocks with other tit species and a garden with four or five at a bird table at any one time, may be feeding 20 or more
Blue and Great Tits form mixed winter flocks, and the former are perhaps the better gymnasts in the slender twigs. A Blue Tit will often ascend a trunk in short jerky hops, imitating a Treecreeper. As a rule the bird roosts in ivy or evergreens, but in harsh winters will nest wherever there is a suitable small hole, be it in a tree or nesting box. Blue tits are very agile and can hang from almost anywhere.
The Blue Tit has an average life expectancy of 1.5 years 
An interesting example of culturally transmitted learning in birds was the phenomenon dating from the 1960s of Blue Tits teaching one another how to open traditional British Milk bottles with foil tops, to get at the cream underneath. This behaviour has declined recently because of the trend toward buying low-fat (skimmed) milk, and the replacement of doorstep delivery by supermarket purchases of milk.
Blue Tit populations often decrease considerably during harsh winters or after poor breeding seasons where the weather is cold and wet, particularly if this coincides with the emergence of the caterpillars on which the nestlings are fed.
1. ^ BirdLife International (2004). Parus caeruleus. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 12 May 2006. Database entry includes justification for why this species is of least concern
* Gill, Frank B.; Beth Slikas and Frederick H. Sheldon (2005). "Phylogeny of titmice (Paridae): II. Species relationships based on sequences of the mitochondrial cytochrome-b gene.". Auk 122 (1): 121–143. doi:10.1642/0004-8038(2005)122[0121:POTPIS]2.0.CO;2. DOI: 10.1642/0004-8038(2005)122[0121:POTPIS]2.0.CO;2 HTML abstract
* Kvist, Laura (2006). "Response to "Taxonomic status of 'phylogroups' in the Parus teneriffae complex (Aves)" by George Sangster". Molecular Phylogenetics and Evolution 38 (1): 290. doi:10.1016/j.ympev.2005.10.012. (HTML abstract)
* Kvist, Laura; J. Broggi, J.C Illera, and K. Koivula (2005). "Colonisation and diversification of the blue tits (Parus caeruleus teneriffae-group) in the Canary Islands". Molecular Phylogenetics and Evolution 34 (3): 501–511. doi:10.1016/j.ympev.2004.11.017. PMID 15683925. (HTML abstract)
* Sangster, George (2006). "c status of "phylogroups" in the Parus teneriffae complex (Aves): Comments on the paper by Kvist et al. (2005). Molecular Phylogenetics and Evolution". Molecular phylogenetics and evolution 38 (1): 288–289. doi:10.1016/j.ympev.2005.10.009. PMID 16314112. (HTML abstract)
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