Thursday's Guardian Country Diary is about a colony of sand martins that nest in this valley on the banks of the river South Tyne at Kirkhaugh in Northumberland.
These birds are the least familiar of all the hirudines - swifts, swallows and martins - that migrate here to breed in summer. That's partly because they often tend to breed in colonies that are well away from human habitation, unlike swifts, swallows and house martins that all share our buildings. Sand martins can only nest in places where there is an eroded riverbank with sandy soil that's soft enough for tunnelling but firm enough resist collapse.
They are also probably overlooked because they are much less colourful than their cousins, but when it comes to their fast and agile flight they are the equal of all of them. They are almost always the first of the quartet to arrive in Spring, and I've often watched them returning to their nesting burrows March.
Click here for pictures of a colony nesting in the riverbank of a tributary of the Tyne near Corbridge. The great 18th. century naturalist Gilbert White believed that when hirudines disappeared in autumn it was because they hibernated underground. That belief arose because naturalists had seen sand martins nesting in tunnels and assumed that swifts, swallows and house martins could burrow into river banks too during the coldest months of the year. Eventually it was realised that they migrate south in winter but it was only with the advent of bird ringing that their wintering destination in Africa was confirmed.
This is Gilbert White's journal entry for 23rd. March 1788.
Mr Churton, who was this week on a visit at Waverley, took the opportunity of examining some of the holes in the sand-banks with which that district abounds. As these are undoubtedly bored by bank-martins, & are the places where they avowedly breed, he was in hopes they might have slept there also, & that he might have surprised them just as they were awakening from their winter slumbers. When he had dug for some time he found the holes were horizontal & serpentine, as I had observed before; & that the nests were deposited at the inner end, & had been occupied by broods in former summers: but no torpid birds were to be found. He opened & examined about a dozen holes. Mr Peter Collinson made the same search many years ago, with as little success. These holes were in depth about two feet.
This exceptionally trusting individual landed on a fence post close to us, to preen.
That beak has an enormous gape, essential for trawling river flies out of the air as it skims the water surface.
Everything about this bird, with its streamlined shape and scimitar wings, says 'speed'