As a licensed bird ringer, I operate a net in my garden fairly regularly
to catch and ring birds that happen to be visiting the feeding stations. For
the most part these are familiar species, like Blue Tit, Blackbird and
Greenfinch, and the information that I collect not only helps to determine
where these birds go but it also helps researchers at the British Trust for
Ornithology to follow changes in annual survival rates over time. Every now and
then my routine ringing receives a welcome boost, either from a report that one
of the birds ringed in my garden has turned up somewhere else (I have had a
Greenfinch go to Guernsey and a Collared Dove go to the Wirral) or because
something unusual has ended up in my net. Over the years I have been fortunate
in my town-centre garden to have caught Blackcap, Redwing and even a juvenile
Reed Warbler. Since it has been a fairly quiet winter bird-wise in the garden,
the sight of a Marsh Tit in the net was something of a red-letter day, adding
to the list of unexpected visitors.
The Marsh Tit is one of a pair of species that look very similar, so
much so that the other partner in the pair, the Willow Tit, was the last
British breeding bird to be identified and named. These two small tits share a
buff, grey-brown plumage, off-white cheeks and a black cap and bib. There are
some subtle differences in these features, notably in the glossiness and size
of the cap, the shape of the bib and the colour of the feather edging on the
main wing feathers. However, recent work has shown that such features may be
unreliable in some cases, leaving the only clear means of separating the two
species as their vocalisations and, usefully, the colour of the biting edge of
the bill. In Marsh Tit the biting edge of the bill is pale along its length;
something that is not seen in Willow Tit. Contrary to its name, the Marsh Tit
is often associated with drier woodland habitats, where it nests in cavities
excavated by other species (including those excavated by Willow Tit, which it
can usurp).
Marsh Tit is the more commonly encountered of the two species within
Norfolk (and indeed elsewhere these days) and it seems to be increasing its use
of garden feeding stations. However, both species have undergone declines in
their breeding populations, a pattern that has caused some concern among
conservationists. Changes within woodland habitats are thought to be the
underlying cause of the decline and efforts are being undertaken to help these
birds recover something of their former status.
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