I was thinking of putting some mulch down around some shrubs to suppress the weeds but unsure of its impact on wildlife - eg birds looking for worms. What is the best type of mulch for wildlife ? Is composted bark any good?
Hi and welcome to the forum.
Composted bark is a very good mulch and over time it will rot down and become part of the soil. Blackbirds have no problems with this kind of mulch and will happily root through it for worms, in fact they will throw it all over the place.
The most natural would be leaf mould, but most of us can't make enough of that, so composted bark is a good alternative. The impact on wildlife would be more from the weed suppression, as many insect larvae, such as those of moths and butterflies, feed on plants we class as weeds. Note that I'm not saying you should let every weed grow!
A trowel in the hand is worth a thousand lost under a bush.
Composted bark from Melcourt Industries is the best. I use it time and time again.