BTO migration blog

Spring and autumn are exciting times for anyone who watches birds. Here on this blog we will make predictions about when to expect migrant arrivals and departures, so that you know when and where to see these well-travelled birds.

Tuesday 22 December 2015

Stopping short

With the very mild weather that has been a feature of this winter also being experienced in central Europe, it appears that quite a few of our winter visitors are here in smaller numbers so far.

After an initial rush of migrants in late October and November, reports of Fieldfare and Redwing have tapered off, with reports on BirdTrack below average so far this month.

Reporting rate of Fieldfare on BirdTrack

Waxwings have arrived in small numbers so far, with several highly mobile flocks reported along the east coast. Wildfowl also appears to be a little thinner on the ground with Bewick's Swan, Bean Goose, Pintail, Pochard and Tufted Duck under-represented this winter. Most appear to be staying further north and east as water bodies remain ice free.

Of course there are other factors than just the weather to consider. Food is the most important component in deciding whether to stay or go. The weather may be mild, but if there is a failure in the food source - Beech for Brambling or winter berries for Waxwings and thrushes for example - then the birds will have to move on. Migration is always a hazardous, especially if it involves a sea crossing, so stopping the migration short where conditions are suitable seems a good option.

Currently there are still a handful of Swallows being reported and these birds are effectively short-stopping. However, these may still move further south if the availability of flying insects is reduced. It does seem unlikely that they will fly as far as southern Africa though - a few spend the winter in southernmost Portugal and Spain. It is anybody's guess where the Swifts reported from Kent, Cambridgeshire and elsewhere in the last ten days have come from and where they might be going to.

Iceland Gull (Nick Moran)

Low pressure systems crossing the Atlantic look set to dominate the weather with even more wet and windy conditions prevalent at least into the new year. Some models show a particularly strong weather system towards the end of the month with strong winds reaching from north-western Greenland and north-eastern Canada all the way to western Britain and Ireland. Similar conditions have brought good numbers of Iceland and Glaucous Gulls to our shores, as well as rarities like Ross's and Ivory Gulls.

Paul Stancliffe & Stephen McAvoy

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