In article , John Towill
writes
I know this is a gardening group, and I am not off topic, honest!.

I have a wren and a wagtail attacking the moss between flags. If only they
removed it all I would be very happy, however I suspect they are really
going after the insects not the moss.

I'm sure they are. Both are invertebrate feeders.

My question is, shortly I will want to clean the moss off, I normally use
sodium chlorate, will this harm the birds? If so what product can I safely
use.

I don't think it will harm them if they were to pick up a small amount
though there is evidence that long-term exposure can lead to infertility
and eggshell-thinning. And as killing the moss will remove the home of
the insects they are seeking, they should soon lose interest. If you are
concerned, though, is there some way you can either cover the area you
treat or erect some bird scares (e.g. CDs strung from poles) just while
the sodium chlorate takes effect and remains on the surface?

--
Malcolm