The marsh tit (Poecile palustris) is a Eurasian passerine bird in the tit family Paridae and genus Poecile, closely related to the willow tit, Père David's and Songar tits. It is a small bird, around long and weighing , with a black crown and nape, pale cheeks, brown back and greyish-brown wings and tail. Between 8 and 11 subspecies are recognised. Its close resemblance to the willow tit can cause identification problems, especially in the United Kingdom where the local subspecies of the two are very similar; they were not recognised as separate species until 1897.

Globally, the marsh tit is classified as Least Concern, although there is evidence of a decline in numbers (in the UK, numbers have dropped by more than 50% since the 1970s, for example). It can be found throughout temperate Europe and northern Asia and, despite its name, it occurs in a range of habitats including dry woodland. The marsh tit is omnivorous; its food includes caterpillars, spiders and seeds. It nests in tree holes, choosing existing hollows to enlarge, rather than excavating its own. A clutch of 5–9 eggs is laid.

Taxonomy and systematics

The marsh tit was formally described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae under the binomial name Parus palustris. It is now placed in the genus Poecile that was described by the German naturalist Johann Jakob Kaup in 1829. The genus name as cited by Kaup is from Greek ποιχίλος, with his interpretation as 'bunt' ("coloured") in German; The specific palustris is Latin for "marshy".

Ten subspecies are currently recognised:

  • P. p. dresseri (Stejneger, 1886) – central and southern England, Wales, and west France. Still present in the far southeast of Scotland but in very small numbers. Slightly smaller than P. p. palustris and more brown or olive-coloured on upperparts and dirtier below. Pale brown tertial fringes can sometimes cause confusion with willow tit
  • P. p. palustris (Linnaeus, 1758) – north and central Europe, from south Scandinavia south to north Iberia, east to central Poland, west Balkans and Greece
  • P. p. italicus (Tschusi & Hellmayr, 1900) – French Alps, Italy and Sicily. As P. p. dresseri, but more rufous on upperparts and paler on underparts

The marsh tit weighs , has a length of (from bill to tail) and a wingspan of . The wing length ranges from . The oldest recorded marsh tit in Europe reached the age of 11 years, 11 months.

Like other tits it has a large range of call notes; most typical is the explosive "pitchou" note, given when agitated, often leading into "pitchou-bee-bee-bee", which can sound like willow tit when not heard clearly.

thumb|right|Note the glossy cap, smaller bib and uniform wings which help distinguish it from the [[willow tit.]]

Marsh and willow tits are difficult to distinguish on appearance alone; the subspecies occurring in the UK (P. p. dresseri and P. m. kleinschmidti respectively) are especially hard to separate. In good photographs, or when caught for ringing, the pale 'cutting edge' of the marsh tit's bill is a reliable criterion; otherwise, the best way to tell apart the two species is by voice. Other plumage characteristics include the lack of a pale wing panel (formed by pale edges to the secondary feathers in the willow tit), the marsh tit's glossier black cap and smaller black 'bib', although none of these is 'completely reliable'; The marsh tit has a noticeably smaller and shorter head than the willow tit and overall the markings are crisp and neat, with the head in proportion to the rest of the bird (willow tit gives the impression of being 'bull-necked').

Distribution and habitat

thumb|right|Typical marsh tit habitat in [[Northamptonshire, England.]]The marsh tit has a worldwide Extent of Occurrence of around 10 million square kilometres. The global population includes between 6.1 million and 12 million birds in Europe alone. The species is classified as Least Concern, though there is some evidence of a decline in numbers. For example, between the 1970s and 2007, marsh tit numbers declined in the United Kingdom by more than 50% and consequently it is on the Red List of species compiled by the UK's Joint Nature Conservation Committee. Research suggests that the cause may be low survival rates from year to year, though the nest failure rate has fallen during the decline. Other studies have shown that reduced diversity of woodland structure and plant species, partly because of the impact of deer browsing, is the cause of the bird's decline.

Data from 157 woodlands covered by the RSPB/BTO Repeat Woodland Bird Survey showed that the abundance of marsh tits in 2003–2004 corresponded with the vegetation present 2–4 metres above the ground, the shrub layer. Data from the 1980s did not show the same results, but marsh tit numbers had increased by 2003–2004 in woods with the most shrub cover. The study concluded that damage to the shrub layer, caused by overgrazing by deer, for example, may make woodland less suitable for marsh tits.

It is a widespread and common resident breeder throughout temperate Europe and northern Asia. It occurs from northern Spain north to south-eastern Scotland and east to western Russia, with a broad gap in western Asia and present again in eastern Asia from the Altai Mountains east to northern Japan and northern and western China.

This species is sedentary, making short post-breeding movements in most of its range, but in northern Europe some move southward in winter. However, marsh tits seem not to perform the occasional irruptions that other members of the tit family do. Most marsh tits stay in their breeding territories year-round; presumably this is related to their food-storing strategy. Analysis of UK ringing data showed that of 108 recoveries (when a ringed bird is found dead or caught by another ringer), 85% were less than 5 km from where the bird was originally caught, and only 1% further than 20 km. Young birds join mixed roaming flocks; adults also join the flocks when they pass through, but do not stray from their territory. Another study in the United Kingdom found that during winter and while foraging, marsh tits spent more time than blue tits in the wood's understorey, and more time lower in the woodland canopy and understorey. Trees and shrubs in 10 breeding territories were also compared. The trees varied significantly between territories, but the shrub characteristics did not, suggesting that the shrubs were more important to the birds. In Wytham Woods, Oxfordshire, marsh tits were "largely absent" from parts of the wood with a dense canopy but poor shrub cover. A study in Bourton Woods, Gloucestershire, England, found that nestboxes were used by marsh tits in successive years in only 20% of cases.

References

  • Xeno-canto: audio recordings of the marsh tit