MARSH TIT, WILLOW TIT

Marsh and willow tits are so similar that they were not recognised as distinct species until 1900. Stuffed museum specimens showed the willow tit wasn’t a newcomer – it just hadn’t been identified before.

The most fascinating thing about marsh and willow tits is the problem of identification. Since the year 1900 when the two species were positively distinguished, much has been found out about the birds and field recognition skills have improved greatly, but the two still present one of the greatest challenges to British bird watchers. It is not too difficult to separate marsh and willow tits from other tits: they are slightly smaller than a blue tit, they are our only two truly black-capped tits (both the great and coal tits have white marks on the crown), and their plumage is a subtle mixture of delicately toning beiges and browns. The problems all start when it comes to deciding which is which.

Sight and sound

The black crown of the willow tit is not as glossy as that of the marsh tit-but this characteristic is influenced by the quality of the light and requires an exceptionally close view, so is risky to rely on. A better guide is the pale patch visible on the closed wing of the willow tit, which is lacking in the marsh tit. This patch is often conspicuous and, if present, is a clear indication that the bird is a willow tit. Unfortunately for bird watchers, damp feathers or the wear and tear caused by the bird scrambling in and out of a nest hole during the hectic summer nesting season can obscure the pale patch, and the lack of it does not necessarily confirm that the bird is a marsh tit.

These differences are so small that it is difficult to identify the birds with any certainty. Fortunately, however, there is another feature which is of great help: the two birds have distinctly different calls, in addition to a variety of sharp notes to keep in contact with each other. Only the marsh tit produces a rather explosive ‘pit-chu’ sound, and only the willow tit a scraping dee-dee-dee or ‘chay-chay’ reminiscent of a squeaking gate hinge.

‘Marsh’ a misnomer

The marsh tit is rather inappropriately named as it is the willow tit which shows a preference for swampy wood-land and copses. This mix-up probably dates from the days before the two species were separated.

The marsh tit prefers dense deciduous woodland, generally with oak. Hornbeam. Hazel and beech trees: these produce a prolific and nutritious seed crop which forms a valuable part of the tit’s winter diet. Some hibernating insects, plus their eggs and larvae concealed in cracks in rough bark, are eaten in winter, but insect food becomes most important as spring advances. The chicks are often fed almost exclusively on caterpillars-the green winter moth caterpillars which usually occur in enormous numbers in oak-woods are specially favoured. As autumn comes and the supply of insects dwindles, berries start to feature in the marsh tit’s daily menu.

In winter marsh tits may join any large mixed flock of tits that moves through their area, but this is only on a temporary basis and they will not move far, deserting the flock as it passes on. It seems probable that many pairs remain in the same territory, winter and summer alike. The territory is large compared with that held by other tits, and sometimes exceeds 10 acres in extent. It is noisily and fiercely defended by the male throughout spring and summer.

Pairing takes place in February and March when the territory has been established by the male, and the search for a nesting site then begins. Competition for a suitable nest site is intense between all the tits; the marsh tit can hold its own against blue tits but will usually give way to great tits. The squabbling over nest sites is accompanied by a lot of aggressive calling, and even by fighting.

Marsh tits choose a natural hole or crevice, usually in a tree or where a branch has broken off, but occasionally in a bank or wall. Sometimes they take over a second-hand nest hole of another species, and chip away the wood to modify the entrance, but they will only very rarely excavate their own nest in rotten timber. The nest cavity is floored with moss and usually lined with hair or fur. In April or May five or six white eggs with red spots are laid (up to a dozen may sometimes be produced). The female incubates the eggs for 13 or 14 days, with only brief excursions from the nest for food. After hatching, the young remain in the nest for 15 days before fledging, being fed by their parents for the whole of that time. In cool, damp summers this period may be extended by several days until a settled spell allows the youngsters to emerge with a reasonable chance of learning to fend for themselves within a few days.

Willow tree dweller

The willow tit is more aptly named since the willow is one of its favourite nesting trees. Willow tits often breed in damp woodland, usually ones with many old. Moss-covered tree stumps. The essential requirement in their breeding area is a supply of live, dying or decaying softwood stumps. Birch and elder are often used for nests, as well as willow.

The willow tit pair excavate their nest-a striking difference, not just from marsh tits but also from other British members of the tit family. It is often impossible to separate male from female willow and marsh tits by sight (the female may be very slightly smaller), but studies of colour-ringed birds have shown that the female does most of the excavating work. Unlike woodpeckers, which leave a conspicuous pile of chippings below their nest hole, willow tits usually carry their debris 10 to 15m (11-16yd) away, and for good measure may pulverise it too, leaving no tell-tale traces at the nest.

Excavating naturally demands strong and bulky neck muscles if the beak is to be effectively used as a combined hammer and chisel.

These muscles give the willow tit a distinctly bull-necked appearance which can be one of the best ways of separating willow from marsh tits in the field.

The nest chamber is 20-30cm (8-I2in) deep, with a carpet of fine roots, grasses and other fibres supporting a nest cup lined with fur or feathers. Unlike the marsh tit, willow tits very rarely use moss. The willow tit’s eggs are very similar to those of the marsh tit but the average clutch is rather larger, at eight or nine eggs. Incubation and fledging times are also similar to those of the marsh tit. Once the chicks have left the nest, it is very difficult to tell parents of either species from the young, although the young may look fluffier.

15. November 2011 by admin
Categories: Ecology/Habitat, General Info, Uncategorized | Tags: , , , , , , , , , , , | Comments Off on MARSH TIT, WILLOW TIT

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