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 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.

Species Focus

Sand Martin

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

By Paul Stancliffe and Scott Mayson

No comments:

Post a Comment

Note: only a member of this blog may post a comment.