Monday, 4 January 2010

Winter gulls

A number of Thetford residents provide handouts to the local ducks and geese, a pattern no doubt repeated in other conurbations across the county. At this time of the year the regular recipients of these handouts, the local Canada geese, mallards (many of dubious parentage) and the solitary muscovy duck, are joined by several dozen black-headed gulls. These delicate gulls are generally more wary, usually keeping a respectful distance from the feeding frenzy but they will take to the air to drop in and grab a piece of unclaimed crust. Just occasionally one of the gulls can be seen sporting a metal ring and, with patience and a supply of bread, it is often possible to read the ring number. Just the other day, one of my colleagues did exactly this, the presence of a German-ringed gull on the river.

It is easy to dismiss black-headed gulls, especially as so many people lump the different gull species together under the name ‘seagull’, but they are worthy of our attention for many different reasons. Black-headed gull is the species most often associated with Man; they can be found on sports-fields, around rubbish tips, following agricultural machinery or scavenging scraps in our towns and cities. Populations of these small, delicate birds occur across most of Europe, their breeding range extending across Asia and even reaching parts of North America. During the winter many of these birds move away, taking them as far south as West Africa, India and Mexico. Most of those breeding in Britain remain here but some move into France and Spain. As the German-ringed bird shows, our wintering population in swelled by the arrival of birds from Scandinavia and the Baltic, making this the commonest gull in the county during the winter months.

The arrival of these winter visitors begins gradually, from July, with the arrival of birds from breeding colonies in The Netherlands. The main arrival occurs during late September and early October, with peak numbers present during January and February. Britain provides an ideal combination of milder weather, an abundance of feeding opportunities and suitable roosting sites; the latter present in the form of large inland waterbodies on which the birds congregate from mid-afternoon. As well as taking scraps, the birds will feed on soil-dwelling invertebrates, especially earthworms, which may either be revealed during farming operations or taken from pastoral land and playing fields. Watch a group of black-headed gulls feeding on an area of short turf and you may see them ‘puddling’, moving their feet up and down to draw earthworms to the surface.

While it is easy to dismiss these birds because of their familiarity, there is more to them than you might first imagine.

No comments:

Post a Comment