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, 13 February 2020

Mid-February to Mid-March

For me, the period from mid-February to mid-March has always felt a bit of a damp squib the renewed vigour of New Year has started to wane but spring is yet to get going properly. That doesn’t mean that it is simply a case of as you were, this time of year can be productive with the first hints of spring starting to appear. As the days lengthen and the first Daffodils burst into flower the birds respond and the dawn chorus becomes ever louder and more varied as the cast of songsters increases. Robins are joined by Blackbirds, Song Thrushes, Dunnocks and Wrens and this will only get better as they are joined by summer migrants later in the season!

The past 4 weeks have seen a continuation of the warm and wet weather that has dominated much of the winter period. Highlights have included 4 Eastern Yellow Wagtails, in Northumberland, Norfolk, Suffolk and Galway, 2 Black-throated Thrushes, 1 in Lincolnshire, which was a first for the county, and the long-staying male in Bedfordshire and, a Lesser White-fronted Goose in Norfolk. On the Shetland Isles, particularly Unst there was a small influx of Glaucous Gulls at the end of January. This arctic cousin of the Herring Gull is an annual winter visitor and numbers vary from year to year, this year has been fairly quiet but on the 18th January, 15 flew north past Lamba ness, Unst. This was then followed first by 67 coming in off the sea during the morning on the 25th January at Burrafirth, Unst, then 56 the next day and 12 on the morning of the 27th January at the same location. Quite where these birds went is open to speculation but there hasn’t been an associated increase anywhere else across the country. The most likely origin of these birds is from Iceland and Greenland as the winds prior to the 25th were almost directly from the southern tip of Greenland and across Iceland before sweeping across the top of Scotland.

1st winter Glaucous Gull - Photo by Scott Mayson

Species focus

February is a month when many of our breeding birds begin to think about the coming season in earnest, and as the days begin to lengthen more and more join the dawn chorus, proclaiming territory and advertising for a mate. Many will also be involved in displaying to achieve the same. One of these is the Goshawk, with February being the month when the males begin their undulating display flight in earnest. This can also be accompanied by a slow, butterfly-like flapping flight.
The Goshawk’s fortunes have seen a turn-around in recent times, the latest population estimate from APEP4, 2020, stands at 620 pairs, up from 280-420 pairs in APEP3, 2013. However, it remains a difficult bird to catch up with due to its elusive nature – it isn’t known as the ghost of the woods for nothing.
February and March is a good time to catch up with Goshawks that are on the move, birds that crossed the North Sea to spend the winter here and non-breeders that are moving around in search of their own territory. That northern populations migrate south during the winter is without doubt but there is very little documented evidence of birds arriving in Britain – there is one recovery of a Goshawk ringed outside of Britain being found here, a bird that was ringed in Southern Norway, being trapped and released in Lincolnshire. However, Goshawks are regularly seen during migration periods at coastal watchpoints and on offshore islands, suggesting migrant Goshawks might be a little more common than current knowledge infers.

Goshawk - Photo by Chris Knight

Weather for the month ahead

The weather over the next 4 weeks looks set to continue to be unseasonably mild with wetter conditions in the northern half of the UK and any drier colder weather being short-lived. At this time of the year, any days of prolonged sunshine should encourage species like Goshawk, Woodlark and Lesser-spotted Woodpeckers to start displaying and nest building. Mediterranean Gulls were once a scarce bird in the UK but now they are expanding their range and breeding at a number of sites, often in large numbers. In early spring they start to acquire their stunning breeding plumage of a jet black hood, white wingtips and scarlet red bill. Look out for them along the coast and in flocks or roosts of Black-headed Gulls.

Mediterranean Gull - Photo by Chris Mills/Norfolk

Most of our winter visitors will be leaving over the next few weeks as they begin to head back to their breeding grounds. Species like Pink-footed and White-fronted Goose and particularly Bewick's Swan will all but have gone by mid-March. Both Redwings and Fieldfares will also be heading back towards Scandinavia over the next few weeks and as a result, many coastal sites will have flocks possibly hanging around for a couple of days as they await favourable weather to make the North Sea crossing.

Birdtrack reporting rate for Bewick's Swan, by the end of February
most birds have left the UK

Any sustained warm weather in early to mid-March could see the arrival of the first summer migrants, these are typically Garganey, Little Ringed Plover, Black Redstart, Wheatear and Sand Martin, although the odd individual of other species such as Swallow and House Martin can also arrive. The arrival of these is not only determined by the weather in the UK but also along their entire migration route from Africa and through Europe. Unfavourable conditions along any part of their route can curtail their progress and set back their arrival in the UK. Both Guillemots and Razorbills will be arriving back at their nesting cliffs during early March in readiness for the breeding season ahead, these will be joined by Puffin, Black GuillemotFulmar and Shag later on in the spring.

Black Redstart - Photo by Liz Cutting

Scarce and rare species that could arrive over the next month include Red-rumped Swallow, Penduline Tit, Hoopoe and Alpine Swift, but as with other times of the year, anything is possible!

Scott Mayson and Paul Stancliffe

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