'Mike' wrote:
Well the birds have flown and they haven't been back to the box, so I
guess they have finished with it for the year.

However, 'should' I clean it out? There's a nice thick layer of soft
stuff in the bottom, why not leave it there for the bird which roosts
there in the winter? Should 'humans' interfere? If it was a hollowed
out tree trunk in the woods, nobody would bring a pair of steps and
clean it out!
Advice please from you experts ;-)

That nice thick layer will house all sorts of parasites and their eggs etc
which will leap on a roosting bird, or worse on next year's chicks. Possibly
in a natural tree hole there would be parasitoids etc which would prey on
them in turn.

So best wait until Autumn, as the law apparently insists, and then empty the
box and sterilise it with a good splash of boiling water. Then put it back
up to be competed over for next season.

BTW if you consult one of the several web sites that detail what goes on in
nest boxes you will see that the roosting male (who is also asserting
squatters rights) will defecate in the box. It is up to his mate to clean up
after him. This is easier in an empty box with a bare floor!

Mike.
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