sally H wrote:

I have just bought vaious bird boxes and should like to put them up around
the garden.

The question is - how do you secure them to the tree trunks because I
thought that banging a nail into the tree will kill or hurt it.

thanks

Just don't use a copper nail and you will be OK, and remove them when
you finally take the box down. You may well need a couple of years
before they are occupied, but if you get them up now there is always a
chance that they will get occupants this year.