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 March 2020
Migration Blog has moved.
The migration blog has a new home, head over to https://www.bto.org/community/bto-blog to check out what species are on the move and where best to find them.
Friday, 20 March 2020
19th March - 25th March
During these uncertain times it can be good to turn to nature, not only to get away from it all but to reflect on how the natural world continues to follow a rhythm regardless of what is happening in our lives. Over the last week, a steady flow of summer migrants reached the UK, most arriving here to breed. A good number of Wheatears arrived during Saturday and Sunday with Portland in Dorset scoring over 100 in a single day, together with 100+ Chiffchaffs, real signs that spring has sprung. The arrival of Wheatears was not restricted to the south with birds reaching as far north as Scotland. Most of these birds will be claiming their territory for the breeding season ahead very soon. The first wave of Ospreys also arrived back to their favoured nesting sites during the last week and no doubt these will be joined by more birds in the coming days and weeks. A few rarer species were picked out with a Male Lesser Kestrel on the Isles of Scilly being the pick of the bunch. There have been a few records of this species recently with the last being seen in October last year in East Yorkshire. The predicted Short-toed Treecreeper from the last blog also materialised with a bird spending a few hours in a garden in Dungeness, Kent before flying off. A Killdeer, a North American relative of the Ringed Plover, was discovered on Lundy, Devon but was only present for a couple of days, perhaps it will be found over the coming week further north, Shetland Isles maybe?
|BirdTrack reporting rate graph for Chiffchaff showing they |
are arriving about the same as the historical average.
Sand Martins spend the winter months in the Sahel, on the southern edge of the Sahara, and are one of the first of our summer migrants to make the northward crossing of the desert in the spring, and consequently one of the first to arrive back here. The numbers that arrive here to breed each year are a good indicator of the winter conditions in the Sahel. In years where the winter rains are plentiful, the overwinter Sand Martin survival is likely to be good, however, in drought years Sand Martin populations can crash. We have seen this happen several times over the years, with one of the most spectacular crashes in the 80s, after which it took a few years for the breeding population to recover. It will be a few more weeks yet before we get an indication of how they might have fared this winter.
The 25-year figure (1992-2017) is currently showing a 3% increase and the latest population estimate has the UK population at 70,300 – 225,000 pairs. Sand Martins can show great nest site fidelity but can also be fickle, breeding successfully at a site one year and completely abandoning it the next; this makes them very difficult to count.
The oldest Sand Martin the BTO has on record was for an individual that was ringed as a juvenile on the Isle of Grain, Medway, in August 1990 that was caught by a ringer in Applegarthtown, Lockerbie, 7 years, 9 months and 1 day later.
Sand Martins, for all of their small size, are tough birds and breed above the Arctic Circle, making the best of the summer glut of winged insects.
|Sand Martin - Photo by Philip Croft|
Weather for the week ahead
With high pressure in charge over the weekend and into next week, the weather should be relatively settled, a welcome change from the past few weeks. The wind will be mostly from the east over the weekend then swinging to a southerly direction for the start of the week, this will allow a continuous flow of migrants to our shores, but what species can we expect? Both Blackcaps and Willow Warblers should start to arrive in ever-increasing numbers, Ring Ouzels will also start to arrive towards the end of the review period. Red Kites are also on the move at this time of year and will be setting up territories for the coming breeding season, look out for them on bright days with a gentle breeze; calling gulls or crows are a good way of alerting you to their presence as they circle overhead. The run of easterly winds over the weekend could produce a few White-spotted Bluethroats, a species many of us dream of finding on our local patch. Other possible scarcities include Hoopoes, Alpine Swifts and Red-rumped Swallow. This is also the time of year that an overwintering American passerine might be found as its migrational instincts kick in, with White-throated Sparrow, Dark-eyed Junco or Yellow-rumped Warbler possibilities in a garden in the next few days and, with more people working at home there is an increased chance that one will be found.
|White-spotted Bluethroat - Photo Philip Croft|
Thursday, 12 March 2020
12th March - 18th March
Dare we say it? It seems like spring has sprung, with the first of the summer migrants appearing on our shores. Sand Martin, Swallow, Wheatear, Willow Warbler and Little Ringed Plovers have all put in an appearance, with Sand Martins making it as far north as Lancashire. The intensity of summer migrants will be as ever weather dependent but with a warm spring and favourable conditions the volume and variety of birds arriving will increase over the next couple of months. The timings of arrival vary from species to species with some species like Osprey, Garganey and Stone-curlew arriving at the start of spring, whilst others like Spotted Flycatcher, Turtle Dove and Swift tend to arrive much later.
The last few weeks have seen little in the way of significant bird movements, warm weather across Europe has meant no significant cold weather movements of wildfowl occurred and, as a result, reports of species such as Smew and Goldeneye have been well below average.
|BirdTrack reporting rate for Smew showing the |
lower than average reporting rate.
The continued run of Atlantic weather systems no doubt contributed to the arrival of an adult Ross’s Gull in Devon and a 1st Winter Laughing Gull in Somerset, both of which normally spend the winter on the other side of the Atlantic. Other rarities have included the long-staying 1st winter drake Steller’s Eider on Orkney and the Tengmalm’s Owl on the Shetland Isles, which has been proven to be a different individual to the one there last year, the term 'like buses' comes to mind!
It is not all about arrivals at this time of year either, it may be best to think of the British Isles as a major airport with both arrival and departures from across Europe and beyond, and the next few weeks will see several species departing for the summer. Often a feature of the autumn, now is also a good time of year to listen for the high pitched 'seep' call of Redwings at night as they head back to Scandinavia. Other winter visitors such as Fieldfare, Bewick’s and Whooper Swans, Waxwings and Brent Geese will also start to depart in the next few days.
|Dark-bellied Brent Goose - Photo bt Philip Croft|
Wintering in the Mediterranean, North Africa and south of the Sahara in West Africa, Chiffchaff is one of the first of the summer migrants to arrive back in the UK, typically in early March. Although Chiffchaff is an overwintering regular, a sudden flush of singing birds in areas where they have been scarce or absent during the winter months is a sure sign that the first wave of migrant Chiffchaffs have arrived. This was definitely the case during the last week, with singing birds being widely reported in the southern half of the country.
In recent times the British breeding population has seen a bit of a surge, increasing by 140% during the last 25 years, at a time when the population of its close relative, the Willow Warbler has been falling, down by 42% over the same period. In 2013 it was estimated that there were 1,200,000 pairs in the UK, by 2020 that number is estimated to be 1,750,000.
The oldest Chiffchaff BTO has on record reached the ripe old age of 7 years, 7 months and 24 days, and was ringed as a juvenile at Winchester College, Hampshire, and found dead at El Kelaa Mgouna, Ouarzazate, Morocco, 2,237km from its birthplace. The longest distance recorded is for a individual that was ringed at Portmore Lough, Antrim and found in Guinea Bissau, 4,816km away.
|Chiffchaffs will be starting to sing at this |
time of year - Photo by Allan Drewitt
Weather for the week ahead
The weather over the coming weekend looks to be set for a run of South/south-westerly winds and with it a rise in temperatures, this should produce another wave of early migrants to the south coasts with more Sand Martins, Swallows, and Wheatears expected, and possibly the first wave of Garganeys and Little Ringed Plovers for the year. Black Redstarts and Firecrests will also be on the move and the first singing Chiffchaffs of the year are likely to involve birds that haven’t come too far and wintered in the UK or near continent. As always coastal sites are likely to get the lion's share of these early migrants but inland waterbodies shouldn’t be overlooked as these are often used by Sand Martins, Swallows, Little Ringed Plovers and Osprey, particularly those that breed in Scotland that often arrive early and make a beeline to their nest sites. Possible rarities that could occur at this time of year include Alpine Swift, Short-toed Treecreeper and Franklin’s Gull; enough to keep anyone happy.
As mentioned earlier, its also worth looking out for departing migrants with species like Brambling, Fieldfare, and Waxwings all moving towards the coast they can turn up anywhere, from gardens to local parks.
The latter part of the week is forecast for a switch to a northerly wind direction which could curtail migration for a few days.
|Little Ringed Plovers are one of our earliest |
summer migrants - photo By Philip Croft
By Paul Stancliffe and Scott Mayson
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|
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 aheadThe 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 Birding.com|
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 Guillemot, Fulmar 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|
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