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.

Wednesday 18 December 2019

Mid December to mid January

The early winter period has been a somewhat quiet affair with little in the way of rare or scarce birds arriving, the standout bird being a rather showy Hermit Thrush that was found on St Mary's, Isles of Scilly. For many, the true highlight was the confirmation that the suspected Paddyfield Pipit was indeed one after a faecal sample was analysed for DNA. The announcement was made at the end of Prof Martin Coillinson's talk at the annual BTO conference, what a way to end a talk! This record will constitute a first for Britain, and indeed Europe, once it is formally accepted by the BOURC.
As for the commoner winter visitors, the numbers of wildfowl continued to increase as birds arrived from far and wide, and it is looking like a good year for Scaup with the BirdTrack reporting rate well above the historical average. Flocks of over 600 were reported from Loch Ryan near Stranraer in late November, and other small groups were reported across the country from Unst, Shetland in the North and Tresco, Isles of Scilly in the south.

BirdTrack reporting rate for Scaup showing a spike in reporting rates since early October.

Scaup wasn't the only wildfowl on the move, numbers of other ducks such as Teal, Wigeon, Shoveler and Pintail all increased, indeed Pintail which had a slow arrival period in late autumn picked up to be more or less where they should be at this time of the year.

BirdTrack reporting rate graph for Pintail showing a steady increase in reports during November.

Woodcock reports have been below average since a peak in early November, no doubt due to milder weather on the continent not pushing them further west, a spell of cold weather will no doubt push more birds to our shores. Other species have also increased in number since the last blog, with increasing reports of Fieldfare, which arrive in the UK a few weeks later than Redwings, but we are still to see the peak winter arrival of Blackbirds from the continent that happens in mid-late December. It is not looking like it will be a Waxwing winter with reports below the historical average and nowhere near the level we saw during the last invasion of 2016.

BirdTrack reporting rates for Waxwing indicating it not looking like a Waxwing winter. 

Waxwing - only a few flocks have been reported this winter.

Species Focus - Taiga Bean Goose

Traditionally, Taiga Bean Goose (fabilis) has been one of the last of the regular winter visitors to arrive in the UK, usually in early December, and one of the first to leave in mid-late January. Birds wintering in Britain are thought to largely originate from the Lapland breeding population and are mostly to be found in two flocks, one in the Yare Valley, Norfolk and the other on the Slamannan Plateau in eastern Scotland. Numbers fluctuate between years but have fallen during the last decade or so as birds take advantage of milder winters on the other side of the North Sea. Each winter a small number of Tundra Bean Geese (rossicus) arrive in the UK. Tundra Bean Goose breeds in northern Siberia and winters mainly in the southern Netherlands, western Germany, the Balkans, France and Spain. Numbers can fluctuate wildly at these sites and can increase during the winter as a result of cold weather movement.

Taiga Bean Goose - Photo by Steve Ray

Cold weather movement

During the winter months populations of birds tend to remain fairly static, however, during periods of cold weather, both here and on the continent, birds can become quite mobile. During these conditions birds can cover large distances in search of snow and frost-free ground and ice-free waters. These movements can occur within the UK with birds moving south as the winter bites further north and can include quite large movements of Skylarks, finches and buntings, Lapwings, Golden Plovers and waterfowl. These movements can occur at any time during the winter in response to falling temperatures. If cold weather hits on the continent birds will move south and west, with some crossing the North Sea. During these conditions we can often see an arrival of waterfowl; Goldeneye, Smew and geese and swans.

Smew can arrive during cold weather events across Europe - Photo by Sarah Kelman

Weather for the month ahead

The weather for much of December looks to be dominated by low pressure sweeping in from the Atlantic, resulting in warm but wet conditions across much of the UK. These weather patterns are unlikely to produce much in the way of vagrant birds but there is still the chance of maybe a Killdeer or American Robin arriving from America. This autumn was also a productive one for American passerines and it is conceivable that another will be discovered overwintering somewhere, Black and White Warbler, Baltimore Oriole, Dark-eyed Junco and most famously of all Golden-winged Warbler have all been discovered during the winter months. If we get any sort of cold blast over the next few weeks visitors from more arctic clines could turn up, with species such as Ivory Gull, Brunnich's Guillemot and Gyr Falcon all possible. The new year is often greeted with renewed vigour by birders as they set out to get their lists off to a start. At this time of year species like Bewick's Swan, Willow Tit, Great Northern Diver and Black-necked Grebe all have their peak in reporting rate and are much sought by those birders of a listing disposition.

Great norther Diver - A species many birdwatchers only encounter
during the winter months Photo by Sarah Kelman.