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 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