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.

Thursday 16 January 2020

Migration blog mid-January to mid-February

Looking back over the last review period little in the way of rarities arrived with the pick of the bunch being an unseasonal Brown Shrikein Cork. Elsewhere, a male Black-throated Thrush in Bedfordshire proved very popular, as did the Lesser white-fronted Goose and Grey-bellied Brent Goose combo in Norfolk, although both could prove elusive at times. The predicted American passerine from the last blog post failed to be found but there is still time! 
With no cold weather to speak of the numbers of species such as Smew, Fieldfare and Redwing all remained well below there historical average and seem unlikely to build over the coming weeks. Both Redwing and Fieldfare, however, may start to appear at coastal locations as they move out of central parts and start to head back towards Scandinavia and Iceland for the breeding season. Over the New Year period, there were some local increases of White-fronted and Tundra Bean Geese which may possibly relate to New Year's fireworks etc scaring birds, indeed radar images in Europe for New Year’s Eve show a sudden spike in birds flying around from midnight onwards. A spell of northerly winds before the Christmas period saw a small increase in white-winged Gulls with both Iceland and Glaucous Gulls reported across the UK. The milder weather has meant a few summer migrants look like they are attempting to overwinter with around 8-10 Swallows reported, including 4 in Galway, a single House Martin in East Sussex and a Swift was seen in Pembrokeshire on the 1st January!

BirdTrack reporting rate for Fieldfare showing a below average reporting rate for the time of year.

The late winter period from mid-January to mid-February is probably the quietest time of the year, whilst some species such as Rook, Grey Heron and Common Crossbill are beginning to start breeding, for most species it is still a few more weeks before they start to think about migrating and breeding. At this time of year, cold weather is the main driver of bird movements but with mild conditions looking to dominate the foreseeable future, this seems very unlikely and thus will be a case of as you were for many species.

Common Crossbills are an early breeder. Photo Philip Croft

Species focus Pochard.

During the winter months, there can be as many as 23,000 individual Pochard in the UK but as a species it has seen its fortunes change. During the last 25 years the wintering population has fallen by 70% - short-stopping (birds spending the winter months nearer to their Eastern breeding sites as winters have become milder) and changes in food availability are thought to be factors in this but there is still unclear what the drivers are. Pochards from the northern and eastern population are highly migratory wintering as far south as West Africa, the Arabian Peninsula and the Equator in East Africa. Wintering Pochard in Britain and Ireland come mainly from the Baltic countries and the former USSR. The longest distance recovery at 5,137km, is of an individual that was shot near Swansea, Wales, that was ringed in Novosibirskiye Islands, Russian Federation, and the oldest on record lived to a grand old age of 22 years and 10 days. This individual was a female, ringed as an adult at Abberton Reservoir, Essex and shot in Odesa Oblast, Ukraine.

Male and female Pochard - Photo by Edmund Fellowes

Weather for the month ahead.

With the short-range forecast pointing towards continued mild wet weather, it looks like the late winter period will pass without any significant cold spells, indeed even the long-range predictions don’t show any signs of any sustained spells of cold weather developing. What this means for migrant species is we could see early arrivals of species such as Garganey, Wheatear and Little Ringed Plovers which are traditionally the first to arrive. This is, of course, dependent on favourable wind directions coupled with good weather further south. Although not arriving here for several more weeks species like Cuckoo, Swift and Nightingales will already have started to move back towards there breeding grounds across Europe. Some of our winter visitors may leave earlier if we have a mild spring and species to look out for include Red-breasted Mergansers, Slavonian Grebes, and Goosanders. Auks, such as Guillemot and Razorbills will start to gather at their breeding cliffs as will Fulmars that leave their breeding cliffs for a short time over winter before returning early in the spring. Common Gulls are for many just a winter visitor and over the next few weeks numbers will drop as they also head off to breed further north, look out for mixed flocks of Black-headed and Common Gulls on sports fields and winter wheat fields. Another Gull to look out for at this time of year is Caspian Gull, a close relative of Herring Gull, this species is sometimes known as a birders bird as it can be very difficult to separate from the aforementioned species. Caspian Gulls breed in Eastern Europe and small numbers, mainly 1st winter birds, turn up here each winter with flocks of large gulls around refuge tips being a good place to find one.

BirdTrack reporting rate for Common Gull showing a decline in reporting rate
 through the month as birds depart northwards.

Common Gull - Alan Drewitt

By Paul Stancliffe and Scott Mayson

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