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
Friday 20 March 2020
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
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