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.

Friday 16 November 2018

A Swift arrival

The migration highlight in the last two weeks was an unexpected arrival of Swifts from 3 November onwards, with three species noted around the country. While there were a handful of Common Swifts reported, the majority of sightings involved the much rarer Pallid Swift, with over 30 and perhaps as many as 50 individuals observed.

BirdTrack reporting rate for Pallid Swift

Pallid Swift is seen annually in Britain in small numbers, influxes involving more than 10 birds had previously occurred only in 1999 (11 records), 2001 (12) and 2004 (15). The majority of the sightings came from the east coast, with only a handful from south coast counties and inland sites. Besides Britain, one was seen briefly in Ireland and up to 20 Pallid Swifts were also noted in the Netherlands, where there had only been 12 records previously.

Pallid Swift by Martin Cade
A potential reason for the influx may be that unusually for European swifts, Pallid Swift is double brooded, with the last brood fledging in October. Additionally, the sustained southerly winds throughout early November may have pushed birds northwards. The presence of a Little Swift at Hartlepool, Durham joining a Pallid Swift already present is intriguing as the nearest breeding grounds are along the southern Mediterranean coast. Did the Pallid Swifts in this influx come from North Africa rather than Iberia or the eastern Mediterranean?

Little Swift by Damian Money
The week ahead looks potentially quite interesting, with high pressure building over western Russia and Scandinavia over the weekend. This could potentially bring a spell of colder weather from the middle of next week onwards, with the easterly winds likely to bring more winter thrushes and wildfowl amongst others to our shores. It is getting a bit late in the season for most rarities by this stage, but given the origin of the winds, a Desert Wheatear, or perhaps even a Desert Warbler, seem like potential arrivals.

Stephen McAvoy

Friday 2 November 2018

Skuas on the move

While not making for the most pleasant observation conditions, strong north to northeasterly winds in late autumn can produce good movements of seabirds and other migrants along the east coast of Britain. The weather last weekend fitted this exact pattern and those who braved the cold, biting wind were not disappointed.

Pomarine Skua by Joe Pender

The most eye catching spectacle was the passage of Pomarine Skuas with several sites logging day totals of more than 100 birds. Amongst the highest counts were 150+ off Flamborough, East Yorksire, 180+ off Gibraltar Point, Lincolnshire and 200+ moving south past Spurn, East Yorkshire. The latter represents a new day count record for the species at the site. However, these counts were eclipsed by the over 500 logged passing Hornsea, East Yorkshire. The BirdTrack reporting rate graph clearly shows last weekend’s movement

The strong winds brought with them a wide variety of other seabirds, including the first large movement of Little Auks. Several sites registered double figure counts, with a high count of over 150 passing Flamborough. Divers and shearwaters were also noted, including a handful of White-billed Divers. The rarest seabird logged was probably the King Eider moving along the North Norfolk coast over the weekend and early last week.

For passerine migrants, there were good counts logged for Redwing and Fieldfare arriving in off the North Sea, while large flocks of Starlings were also noted. As in the previous week, a few flocks of Waxwings were noted moving west with the thrushes and Starlings - it is well worth keeping an eye on any berry rich hawthorns in the coming weeks!

A common theme in the last weeks has been a rapid switch of wind directions, and this weekend is no exception. After the spell of northerlies in recent days, the prevailing wind moves back to a south – southeasterly direction as the remnants of Hurricane Oscar pass northeast off the coast of Ireland and Scotland. Having stayed well out in the Atlantic in the last week, it is unlikely that this weather system will bring any new arrivals of North American origin, though potentially the first white-winged gulls could arrive, and rarer gulls are always a possibility, including Laughing or Franklin’s Gull.

Stephen McAvoy

Friday 26 October 2018

Eastern Promise

As expected, the northerly winds meant that migration was relatively quiet this week. However, a trickle of birds continued to arrive, most notably Common Crossbills. From Tuesday onwards, daily totals of up 200 birds were noted at Sandwich Bay Bird Observatory, Kent. Smaller numbers were recorded elsewhere along the south coast. The BirdTrack reporting rate graph shows as above average for the last few weeks so it is worth checking any local sites for birds on the move.

Thrushes and finches continued to arrive, albeit in smaller numbers with counts from bird observatories along the east coast in the low hundreds for both Fieldfare and Redwing. Most sites also held a Short-eared Owl or two and late October/early November is the peak time for this species based on BirdTrack reports.

Short-eared Owl by Mark Taylor/BTO

More unusual migrants included small numbers of Stock Doves arriving in off the North Sea along the south and south east coast. While birds breeding in Britain and Ireland are considered to be sedentary, the populations of Stock Dove in Scandinavia and eastern Europe are migratory. A handful of Waxwings were reported along the east coast, with most seen as fly-overs only.

Over the course of the weekend, the winds gradually shift from northwest to east, with strong northerly winds forecast for Saturday morning. Over 70 Pomarine Skuas were logged passing Titchwell, Norfolk this morning and tomorrow looks like a good day for this species, and other skuas, to be found along the east coast. The first Little Auks of the autumn may well be reported moving past offshore as well.

Little Auk by Morris Rendall/BTO

Based on current forecasts, the winds will remain easterly until Tuesday at least, which may well bring an arrival of Siberian migrants, including commoner species such as Brent Goose and Bewick’s Swan. Given the origin of the winds, a late arrival of Yellow-browed and Pallas’s Warblers seems possible, and any Wheatear is worth checking for something rarer, such as Desert or Pied Wheatear. There is always the potential for something unexpected turning up – a Siberian Rubythroat would brighten any day!

Stephen McAvoy

Friday 19 October 2018

Rare arrivals from east and west

Arriving quickly from the east coast of the United States and Canada, the remnants of Hurricane Michael did not directly impact Britain and Ireland last Monday, diverting southwest towards NW Iberia at the last moment instead. Despite this, the outliers brought several very rare North American birds with them. The first species to be found was also one of the rarest, with Britain’s second Grey Catbird found at Land’s End, Cornwall late on Monday. It remained on site all through the week, allowing many birders to catch up with this species. The offshore islands closest to the track of ex-Hurricane Michael were also good places to be with Cape Clear, Co. Cork holding a triple crown of Swainson’s Thrush, Scarlet Tanager and the first Veery for Ireland. Birders on the Isles of Scilly discovered Bobolink, Grey-cheeked Thrush and Red-eyed Vireo, though the former was only seen briefly. Away from the southwest, there were sightings of Red-eyed Vireo on Inishmore, Co. Galway and a Baltimore Oriole on Barra, Outer Hebrides. The fast moving nature of this Hurricane, taking just over 48 hours to cross the Atlantic, likely helped these birds survive the crossing. Who knows what other species may have been discovered if it had made landfall in Ireland or Britain?

Following on from the strongly southerly winds the previous weekend, Pallid Swifts were found in Kent, East Yorkshire and Northumberland. However, these were outshone by Britain’s first White-rumped Swift at Hornsea Mere, East Yorkshire last Sunday. With an increasing population in Iberia, this species should now be on the radar in similar conditions in future years.

Along the North Sea coast of Britain, strong northeasterly winds last Monday brought fresh arrivals of thrushes and finches arriving ‘in off’. Redwing, Fieldfare, Goldcrest and Brambling arrived, while scarcer migrants included Bluethroat, Red-flanked Bluetail, several Great Grey Shrikes and a probable Two-barred Warbler in Norfolk. The first Waxwings of the autumn were also reported from Shetland, Yorkshire and Norfolk – will this winter see another invasion?

Waxwing by Jeff Baker/BTO

Looking ahead, the weekend looks set to be dominated by high pressure, and the calm mornings are ideal for visible migration watches with larks, thrushes and finches on the move. The reporting rate graph on BirdTrack shows that late October is the peak for Skylark, Siskin and Brambling amongst others. One to listen out for is Richard’s Pipit, with fly-overs likely to be found anywhere. The BirdTrack reporting rate graph shows a clear peak in late-October, and it is well worth being familiar with the flight call (for example

Reporting rate graph of Richard's Pipit

On Sunday afternoon, the wind looks set to switch to northwesterly over most of Britain and Ireland, which will likely help birds staging from Iceland to our shores, for example Brent Goose and Whooper Swan.

Stephen McAvoy

Friday 12 October 2018

Looking east and west

The spell of northeasterly winds last weekend appears to have opened the floodgates for birds wanting to cross the North Sea from western Scandinavia. There was a notable passage of thrushes, consisting mainly of Redwing and Song Thrush, with a few Ring Ouzel noted. The movement also included some flocks of Fieldfare – appearing a little early based on the BirdTrack reporting rate.

Fieldfare by Luke Harding/BTO

Other winter visitors on the move included Whooper Swan and Brent Goose, while good numbers of duck were reported moving past coastal watchpoints along the east coast, especially on Sunday when the northeasterly winds were at their strongest.

Scarcer species noted included several Barred Warblers, the first Great Grey Shrikes of the autumn and the first significant arrival of Yellow-browed Warblers along the east coast.  Up until this weekend, it had been a very quiet autumn for this species by recent standards. However, 39 logged at Spurn, Yorkshire on the 7th October was both a record day count for the site and a very good count for this autumn. Over 20 were also logged at nearby Flamborough Head, Yorkshire, and single figure counts came from many coastal sites.

Great Grey Shrike by Graham Catley/BTO

Although the winds switched back to west–southwesterly from Monday onwards, these were sufficiently light that birds managed to cross the North Sea, with further arrivals of Song Thrush and Redwing. New arrivals included the first Brambling and several Olive-backed Pipits. Above average numbers of the latter have been reported from Poland and Germany so far this autumn, so more may yet be found.

On Thursday and Friday, the winds switched to a southerly direction in the wake of Storm Callum moving north off the west coast of Ireland. These winds originate from the Mediterranean basin and mid to late October is peak time for Pallid Swift in Britain so it will interesting to see if the southerly winds will push any our way.

Pallid Swift reporting rate on BirdTrack

Looking ahead, there are two weather systems to watch. On the east coast of Britain, there is potential for more northeasterly winds on Monday and Tuesday, which will likely bring more Scandinavian migrants, and perhaps something rarer. In the southwest, the remnants of Hurricane Michael could arrive on the same day. Having caused significant damage in northwestern Florida, this storm moved rapidly along the east coast of the United States and Canada. As of this morning, the storm could reach southwestern Ireland and Cornwall on Monday lunchtime, though there is still some uncertainty on the precise track the storm will take across the Atlantic. If it does reach our shores, it may well bring some very rare North American birds, with likely candidates including Chimney Swift, Red-eyed Vireo and Grey-cheeked Thrush. There is always the chance of something unexpected – a repeat of either Canada or Golden-winged Warbler would be very welcome!

Stephen McAvoy

Thursday 20 September 2018

Mixed bag of migrants

With a turbulent run of weather forecast for the coming week it makes predicting what will be migrating rather interesting shall we say. As deepening depressions rattle their way across the Atlantic they bring strong westerlies to our shores and periods of heavy rain. These weather systems cannot only dump large quantities of rain but can also provide us with a smattering of transatlantic vagrants, such as American peeps (or sandpipers as we know them) and maybe a rare 'Yank' warbler. Pectoral Sandpiper and Semipalmated Sandpiper have already made landfall in the UK this year but are likely to be joined by more individuals as well as the possibility of other species such as Least Sandpiper or Killdeer.
Strong westerlies can make for good seawatching conditions along the west coast with species such as Sabine’s Gull and Long-tailed Skua mixed in with the more expected Arctic and Pomarine Skuas and Kittiwakes. Sometimes these species are forced further inland by the strong winds so any reservoirs or large lakes are worth checking.

Sabine's Gull - Moss Taylor

As these weather systems make their way across the UK they will start to draw in a northerly and easterly airflow, opening the door for another suite of birds to arrive. For many birdwatchers this time of year is synonymous with Yellow-browed warbler, once the preserve of twitchers this is now an expected migrant with several hundred birds turning up in a good year. No longer is it just a coastal bird either, with individuals being found with greater regularity at inland sites. At this time of year any wind direction with a hint of east opens the possibility of something ‘off the radar’ turning up from the far east and have include Thick-billed Warbler, Brown Flycatcher and Yellow-browed Bunting.
For those species that arrive here for the winter northerly winds will aid their migration and numbers of Pink-footed Goose should increase and other wildfowl such as Shoveler, Wigeon and Teal should also arrive in ever growing numbers.
Reporting rate for Shoveler from BirdTrack

Waders will also be on the move as this years young, which typically migrate after their parents, start their first migration to wintering grounds, Bar-tailed Godwit, Knot, Turnstone and Sanderling can often form large groups and can turn up anywhere.

Sanderling - Jill Pakenham

Friday 14 September 2018

Migration reaching the peak period

Mid-September to mid-October is peak autumn migration time; this is the period when most birds are on the move, both in and out of the country. It has been estimated that at this time as many as 50 million birds could be on the move.

Meadow Pipit BirdTrack reporting rate

Right now Meadow Pipits and White Wagtails should be moving in force. However, the weather forecast for the next week doesn’t look very conducive to a large movement of any of these birds. We have largely been in westerly airflow for over a week now and it has turned up a few North American birds, White-throated Sparrow on Foula, Shetland, being amongst the highlights. It is difficult to see if this will continue over the next week, Hurricanes Florence, Joyce and Helene are really stirring up the weather in the Atlantic. It does look like the northern half of the country will remain in westerly airflow for longer than the southern half, with air being drawn out of the Labrador Sea bringing the possibility of a few more North American waders, Wilson’s Phalarope and Short-billed Dowitcher could be on the cards.

Whinchat by Mike Weston

In amongst this dynamic weather there will be high-pressure to the south for a little while resulting in fairly calm conditions over the channel, this will allow departing birds to get a move on and we could see hirundines make their last big movement of the year over the weekend, along with a few Yellow Wagtails and Whinchats.

Yellow-browed Warbler by Andy Mason

Even though we have already recorded our first Yellow-browed Warblers (they seem to be getting earlier and earlier) birds wanting to cross the North Sea from the north will have to wait a little longer, and it might be another week or more before we start to see arrivals of Redwings and Chaffinches and movements of Linnets and Redpolls.

Leach's Petrel BirdTrack reporting rate

It looks like the western half of the country will be the place to be. Sabine’s Gulls, Grey Phalaropes and Leach’s Petrels might all put in a performance, along with a few skuas and divers.

Friday 31 August 2018

The first weekend of the autumn is looking good.

The weather forecast for this weekend should provide plenty of opportunity for migrant birds wanting to get moving and for those birdwatchers in search of them.

It isn’t going to be a classic forecast for continental migrants to get drifted here but it does have some promise. High pressure will be over Scandinavia for at least the next day or two, which will bring a hint of easterly airflow towards Britain and, any birds tempted by the good conditions to the north east of us might find themselves over the North Sea and heading towards our shores.

Red-backed Shrike by Neil Calbrade

At this time of the autumn we could be looking at the arrival of Wheatears, Whinchats and Redstarts, and perhaps the first Pink-footed Geese and Fieldfare. Amongst the scarce migrants, Barred Warbler, Icterine Warbler, Red-backed Shrike and Wryneck are all classic early autumn arrivals.
 Whinchat BirdTrack reporting rate

Redstart BirdTrack reporting rate

At sea, terns will also be on the move, Arctic and Common movements can be spectacular right now, and can include the occasional Black and Roseate Terns. These tern movements are inevitably followed by skuas and now is a good time to look out for the odd Long-tailed Skua amongst the Arctics.

Long-tailed Skua by Joe Pender

At least in the southern half of Britain the winds look to be light and at times from the north. This may well be the trigger for a large movement of Swallows and House Martins out of the country and we might all notice fewer of them around during next week.

The northern isles will be blasted by westerlies that have tracked across the Atlantic in the last day or so. These winds might bring something from North America with them, and if they do it might be something very special this early in the season. Of the ten accepted British records of Yellow Warbler half have occurred at the end of August, with the most recent being a two-day bird at Portland, Dorset in 2017.  From the east the only 2 records of Little Whimbrel have been at the end of August, fingers crossed for a third!

Scott Mayson and Paul Stancliffe

Friday 27 July 2018

Autumn here we come

It seems a shame to mention the autumn whilst we are enjoying an amazing summer but autumn migration is gathering pace already. All of the BTO satellite tagged Cuckoos had left the UK by the end of June but since leaving some of them have had a rapid migration south; five have already successfully crossed the Sahara, you can follow all fourteen tagged birds here.

Swift numbers are beginning to build at coastal migration watchpoints as they too begin the long journey south, along with a few Swallows, House Martins and Sand Martins. The first warblers are also on the move with Willow and Sedge leading the way, and a few Lesser Whitethroats too. Many of these warblers will be this year’s young and will have nice fresh plumage and will stand out from the more worn looking adults.

Swift occurrence falling in BirdTrack

The most obvious migration happening right now is that of the waders and numbers will continue to build over the next few weeks. Early July saw Knot, Redshank, Spotted Redshanks and Bar and Black-tailed Godwits on the move but these have now been joined by Curlew and Green and Common Sandpipers, along with a few Whimbrel. It won’t be long now before the stints and Wood Sandpipers move too. A westerly airflow at this time of year can also produce the occasional American wader such as White-rumped, Pectoral or Baird’s Sandpiper and maybe something rarer like a Wilson’s phalarope!

Wilson's Phalarope by Andy Mason

Balearic Shearwaters, which breed in the Mediterranean, migrate to spend the autumn in the Bay of Biscay and the English Channel. Seawatching along the south coast at this time of year can produce good numbers especially during strong onshore winds. Occasionally birds make it further north and in to the North Sea.  A handful of Great Shearwaters and Wilson’s Petrels have also been seen off southern Ireland and in the southwest approaches, these will be making their way south to breed on remote South Atlantic islands.

Balearic Shearwater by Joe Pender

From the weather forecast it seems that the fairly settled weather will be with us for a little longer yet, however, during the next few days there are a few weak fronts that will cross the Atlantic. This should provide the right conditions for those seabirds that are crossing the Atlantic too and we ought to get a few more records of the large shearwaters and a few more Wilson’s Petrels too. The first Sabine’s Gulls might also put in an appearance as winds straight out of the Labrador Sea head this way too.

Paul Stancliffe and Scott Mayson

Thursday 12 July 2018

Return migration is under way

July is a fantastic month for birding. Some species will have already finished breeding and will be making their way south with this years offspring to their wintering grounds. This can bring lots of rare and exciting birds to the UK- particularly around the coasts, but also to some inland locations.

Spotted Redshank by John Harding/BTO

The majority of the return migration happening at this time of year involves waders. First come the failed breeders, then the adults that have successfully bred, and then finally the young who have to navigate their way to the wintering grounds with no previous experience. Species whose numbers will increase over the next couple of months include Green Sandpiper, with the BirdTrack reporting rate almost doubling in the last two weeks, Greenshank, and Common and Wood Sandpipers. Numbers of Ruffs reported this week were also higher than average, possibly an indication of a poor breeding season, and are set to increase further until late August. Spotted Redshanks are one of the first waders to return with some birds heading back in late June and throughout July and in to August. Interestingly, the male Spotted Redshanks stay to raise the young in Scandinavia whilst the females set off earlier- a reversal of the typical gender roles in birds. Most of the males and young leave Scandinavia in the second half of July.

BirdTrack Green Sandpiper reporting rate graph

Our Swifts didn’t arrive on time this year, and whilst many of us were concerned that they wouldn’t return, they gradually appeared about two weeks late and increased to near-normal reporting levels compared to recent years, although still a little below the historical average. Mixed groups of Adults and young can be seen gathering over towns and cities before they depart for the winter. It will be a shorter stay this year, but at least they did come eventually!

Little Gulls by Andy Mason

Another species increasing at many coastal sites right now is the Little Gull: this species should be searched for in any gull flock, where its small size makes it stand out. At some regular sites, such as Hornsea Mere in East Yorkshire, triple figures have been noted. This species also has a tendency to occur at inland reservoirs and lakes where it can be seen hawking over the water, often dipping down to take insects from the surface. In July and August, Yellow-legged Gulls from the Mediterranean reach the UK as they disperse around the continent, providing birders with quite an identification challenge. Numbers of UK reports of this species have more than doubled over the last week and they are still rising, so this really is the time to scan gull flocks for these too.

BirdTrack Yellow-legged Gull reporting rate graph

Scarcer birds being noted currently include Spoonbill and Roseate Tern. The Roseate Tern is a scarce breeding bird within the UK and the birds being reported away from the breeding locations at this time of year will be a mixture of failed breeding birds from the UK and those from colonies further afield, soon they will be leaving our coasts for those of West Africa. Although Spoonbills can be seen here in all months of the year, many family groups visit the UK in July, right after breeding, look out for younger birds with pale bills and black wingtips.

It’s also worth mentioning Cuckoos. The adults have left the UK already as they have no parental responsibilities they are able to leave early. Two of the satellite-tagged Cuckoos (Victor and Bowie) have already crossed the Sahara Desert! The other tagged birds are currently in Spain and France, with one on an island in Croatia. The latest to leave the UK, Carlton II, left on the 2 July - this goes to show just how quickly Cuckoos can leave the country after breeding. You can follow them all as they make their way south.

Joshua Carter
BTO Work Experience

Thursday 31 May 2018

Has the 2018 spring migration come to an end?

There is a general feeling that numbers of some of our long-distance summer migrants are still on
the low side, despite an arrival of birds in the easterly airflow at the weekend. Up until the last few
days birds such as Swift, House Martin and Swallow were indeed running late with numbers
looking poor too, but with suitable conditions during the Bank Holiday weekend they have caught
up somewhat. However, it is looking unlikely that they will reach their historical averages on the
BirdTrack reporting rate graphs.
Reporting rate graph for House Martin

Reporting rate graph for Swift

Reporting rate graph for Swallow

Even though we are at the end of May there is still time for a few migrants to arrive. We could
still see birds such as Spotted Flycatcher on the move, and maybe a last pulse of Swifts, although
if we don’t see the latter in the next week it is difficult to see any more arriving after that and it
might just be a low year for Swifts. Nightjar is one of the last of our migrants to arrive and now is
a good time to come across one at a daytime roost. On migration they don’t always pick the best
site and can be seen almost anywhere.
A day roosting Nightjar. Scott Mayson

Quail is a very hit and miss bird in Britain, with huge variation between years but in some years
we see hardly any at all until the first week of June. On any warm, still evening during the next
couple of weeks it is worth getting out and listening around the edge of cereal fields and listening
out for the distinctive ‘wet my lips’ call of the Quail.
Reporting rate graph for Quail, now is the time of year to listen for them.

The weather looks like it is forecast to be all over the place for at least the next four or five day
but does include a continuation of easterly airflow for the next day or so before a period of light
winds from the north west. For any birds still held up this should provide them with a window of
opportunity, and we might see a small movement of House Martins and Swallows. We could also
see some waders on the move, such as Greenshank and Wood Sandpiper. This is also a great time
for rarer wader, Terek Sandpiper could be on the cards but a Marsh Sandpiper would do nicely.
Paul Stancliffe

Scott Mayson