Sand martins are like small brown swallows in appearance. They also migrate from Africa in spring to nest in Britain and Ireland. Their nest burrows are normally dug in west facing, exposed faces of sand or loam, preferably with a three meter drop below and with water nearby, over which they hawk, gathering flying insects.
There has been a steady decline in the sand martin population, so that it is now less than 10% of what it was in the 1960s. This is thought to be largely due to climate change in the Sahel where they over-winter. However, there are many hazards for them to overcome in their huge to and fro migrations.
So what is the mushroom link? A vigorous colony was spotted last year nesting in an old ‘cliff face’ of peat, 20 or 30m from an area where peat was being extracted for casing. Peat is an unusual nesting substrate and one that may not previously have been recorded. However, it appeared to be successfully used, except where martins also tried nesting at the top of the sloping sides of deep drainage channels. With no sheer drop below, the nests and chicks were pulled out by some predator, possibly a mink or pine-martin (judging by the claw marks in the soft peat).
The law protects most wild birds, particularly during the breeding season. There are large fines for disturbing nests. Sand martins, being under threat for other reasons, are protected particularly keenly. If any casing producers have noted them endeavouring to nest on their land they would be obeying the law and doing their bit for conservation if they reserved a suitable nesting site to one side, away from their extraction area.
In a similar vein, swallows will soon be searching round farm buildings for nest sites. Doors should not be left open to encourage them and then closed belatedly after they have started to nest.
