In writing about sand-martins, the smallest of the ‘hirundines’ (s.p.b.s.), the Rev. White focussed on their manner of nest building. Unlike swallows and house martins, sand-martins built their nest in a hollowed-out hole in an earthen bank, these holes, he claims, being up to two feet in depth. White develops a moral point from this excavation ‘Perseverance will accomplish anything: though at first one would be disinclined to believe that this weak bird, with her soft and tender bill and claws, should ever be able to bore the stubborn sand-bank without entirely disabling herself; yet with these feeble instruments have I seen a pair of them make great dispatch’. I have seen a few examples of these nesting sites in two quite separate but geologically similar locations – at a few points in the cliff-face along the Holderness coast nest colonies of sand-martins can be seen as shown in the photo above. In all cases the nest holes are confined to a particular band of sandy clay, rather than above or below. Clearly the birds can work-out which band is best for their purpose, a speculation that White wondered about. The other location I know of is at South Ferriby cliff, a section of the south bank of the Humber Estuary. Here an area of glacial deposition, as with the Holderness coast, forms a modest cliff readily undermined by spring-tide marine erosion, and here the band of soil chosen by the sand-martins is very narrow so the holes are more or less in a line.
White writes that sand-martins ‘disclaim all domestic attachments’, unlike other ‘hirundines’ keeping well away from houses and built-up areas. He also notes that they, like the others, feed on insects on the wing. Apparently some of his contemporaries had dug-out these holes in winter believing that the birds might hibernate there, but found none.
The letters of the Rev. Gilbert White are a refreshing example of a life lived in close observation of Nature in a given locality, not the best, not the worst, but given.