Willow Tit

Breeding distribution of Willow Tit during the breeding-seasons of 2008 to 2011

Breeding distribution of Willow Tit during the
breeding-seasons of 2008 to 2011
(Click to enlarge)

As we look at the Atlas maps, and consider the conservation implications of the changes that they document, it’s interesting to think about the parts played by habitat change and dispersal in the way that new areas have been colonised, by species such as Nuthatch, for instance, and to wonder about the processes that lead to local and regional extinctions.  For the Willow Tit, which is one of our most sedentary of species, what hope is there once it has been lost from a parish or county?

The map alongside shows the breeding distribution for Willow Tit over the four summers of the Atlas period, with shocking gaps to the south and north of London and across large swathes of the West Country.  There were records in East Anglia but pairs are being lost here too.  When I heard one singing near the BTO headquarters this spring I was asked to fill in a field description, simply because the species is now so scarce.

Breeding distribution of Willow Tit during the breeding-seasons of 2008 to 2011 (right).

Winter distribution of Willow Tit during the seasons of 2007/8 to 2010/11

Winter distribution of Willow Tit during the seasons
of 2007/8 to 2010/11
(Click to enlarge)

Willow Tits are constrained by their breeding habitat, especially by the need to find decaying standing timber in which they can hollow out nest holes with their tiny bills.  Wet woodland may well be a less widespread habitat than it used to be but there are probably other processes at play.  Winter records for Willow Tits are slightly more widespread than those for the breeding season.  Although the species has a reputation for poor dispersal, perhaps they do move around more locally than we think that they do?  Birds breeding in isolated damp woodlands may well be joining with other tits and visiting gardens and other places where birdwatchers are active.  Given the concerns that there are about the decline of the species, a lot of work has gone into validating the records of Willow Tits in areas where they are scarce or from which they are thought to have disappeared.

Watch a BTO training video on separating Marsh and Willow Tits.

Winter distribution of Willow Tit during the seasons of 2007/8 to 2010/11 (left).

Breeding distribution of Marsh Tit during the breeding-seasons of 2008 to 2011

Breeding distribution of Marsh Tit during the
breeding-seasons of 2008 to 2011
(Click to enlarge)

Looking back at the figures for Marsh Tit and Willow Tit from the first Breeding Atlas of 1968-72, there was very little difference in the broad spread of the two species, with Willow Tit in 1220 10-km squares and Marsh Tit in 1376.  In the period between 1968-72 and 1988-91, the number of Marsh Tit squares dropped to 1133 and the number of Willow Tits to 1200.  It is hard to believe that twenty years ago, Willow Tit was more widespread than Marsh Tit, albeit marginally so. 

In the period since 1988-91, the number of 10-km squares with breeding Marsh Tit has decreased slightly but Willow Tit is now found in only  558 squares.  Breeding Bird Survey data for the period 1995-2010 indicate a population drop of 22% for Marsh Tit and 79% for Willow Tit.

Breeding distribution of Marsh Tit during the breeding-seasons of 2008 to 2011 (right). 

The change in breeding distribution of Willow Tit

The change in breeding distribution of Willow Tit
(Click to enlarge)

The change maps will probably be the most eagerly scanned features of the new book, when it is published in November.  Although there is an almost continuous band of pink running from northeast England to the western tip of Wales, indicating areas in which the species has been found during each of the three breeding atlas projects, the solid phalanx of black triangles across the southeast corner represents the biggest block of local extinctions for any species.  The 50% reduction of the breeding range of Willow Tit between 1988-91 and 2008-11 makes this the sixth largest contraction across all species, beaten only by five scarce breeders – Fieldfare, Goldeneye, Hawfinch, Ruff and Common Scoter.  The next resident species in the list is Corn Bunting, 36% down and in 15th position.  Whinchat, Wood Warbler, Turtle Dove and Lesser Spotted Woodpecker are all between 37% and 34%.  Perhaps these figures put the plight of the unassuming (or even dull, brown) Willow Tit into context?

The change in breeding distribution of Willow Tit (left): red upward-pointing triangles are new gains since 1988–91, open upward-pointing triangles are gains between the first two breeding atlases and solid salmon areas have been occupied since at least 1968–72.  Downward-pointing triangles indicate losses; black are recent losses and open triangles are losses between 1968–72 and 1988–91.

by Graham Appleton