The other day I noticed house martins gathering mud from a puddle to build their mud hut nests under nearby eaves, so I parked alongside to try for some pictures.
One surprise when transferring the pictures to my computer was this one with a parasitic flat fly on its nape.
A bird-ringing friend tells me that he has often found these blood sucking parasites on house martins. Certainly, I know they can be found spending the winter in old martin nests.
As always in nature, every discovery simply raises more questions.
Surely the nest of an insectivorous bird is a very unsafe habitat for any insect? Or have they evolved a foul taste to avoid being eaten?
Also, why do house martins not preen one another? Maybe they do, but find the flat flies distasteful?
Also, have these flies evolved a strategy to climb off the birds in autumn?
If not, they are surely in for the longest piggy-back ride in history as the birds set off for sub-Saharan Africa.
Please, dear reader, do not panic about parasites if you have house martin nests under your eaves!
It is very rare for flat flies to interest themselves in humans.
Remember your house martins have endured an epic transcontinental migration to reach your house.
Humans should feel highly honoured to play host to nesting house martins!
However, not everyone is as welcoming as I would be if I had the good fortune to be chosen.
Might I remind these houseproud folk that it is illegal to interfere with an active house martin nest, not to mention a bit soul-less!
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