Friday, 13 January 2006

A late winter spectacle

As I have noted before, the long winter nights can cause problems for small birds and a number of species are known to roost communally to reduce heat loss. Such roosts can provide a spectacle for the winter birdwatcher, as tens, hundreds or even thousands of individuals congregate at favoured sites. Many readers will know of the huge starling roosts that may form at this time of the year but how many are aware of the roosts of pied wagtails or reed buntings that form each night throughout the winter months? Pied wagtails may gather to roost on large buildings, especially on some of the county’s larger supermarkets, and their loud ‘chis-ick’ calls fill the late afternoon air as individuals arrive from scattered feeding sites just before dusk. These congregations provide an ideal opportunity for teams of licensed bird ringers to catch and ring large numbers of birds, helping researchers to understand more about bird movements and survival.

Last Sunday afternoon, I was part of a team catching and ringing pied wagtails and reed buntings at a small roost in southwest Norfolk. The roost was in a reedbed, an ideal place to spend the night perched above open water and safe from predators, and the site has been used over a number of winters, although not always by the same species. A couple of winters ago, there were large numbers of starlings using the site. This winter there are very few starlings but fairly good numbers of wagtails and buntings. We arrived to set up our nets at two-o’clock and, once erected, all we had to do was wait for the arrival of the birds. Periodic checks of the nets during the intervening time revealed a number of wrens, all of which were local birds that had been caught at the site during previous summer sessions. Wrens often move into reedbeds during winter because this is one of the best places to find the invertebrates on which to feed.

As dusk approached, wagtails and buntings began to arrive. Parties of wagtails gathered together and wheeled about the sky calling, a spectacle that lasted for half an hour or so. The numbers of birds increased and then groups of individuals dropped down into the reeds, with some ending up in our nets. Quickly and efficiently our team removed birds from the nets and processed them, noting down details of wing length, weight and age (not an easy thing to discern in a pied wagtail) before letting them go so they could return to the roost. Other members of the team had, by this stage, packed away the nets and we were left listening to the occasional shuffles of birds moving to favoured positions in the reeds.

No comments:

Post a Comment