Dear Housemartins ....

.... Ahem !

Well, it is almost mid May, and you haven't turned up.

Usually you put in a fleeting visit in mid April and disappear for a few weeks. Then you arrive for real and get on with the business of saying hello again to your summer home and raising a family (and more).

But this year - we haven't seen you.

Now I know that you - like our other migrants - are African birds who move north for the summer, facing a perilous journey as you make your way to your summer residences.

I also know that you are one of our most mysterious migrants. How extraordinary that no-one yet knows where you spend the winter. Unlike your cousins the barn swallows, who spend their time swooping over the grasslands of southern africa.

I always look forward to your return. You are a chatty, sociable hirundine, a bit chubbier than the swallow, a bit more taken for granted than the sand martin, but sleek and with a white rump that is your big giveaway.

So are we going to have to see summer through without you. Looks increasingly probable. The only glimmer of hope is the sight of martins a couple of days ago nearby (was that you ?) and most tantalisingly a couple of recent droppings below the nest (was that you ?)

It would be sad not to have you back.