So are the GBH picking off ducklings? Around here it seems that the Wood Ducks start with 12-15 hatchlings but most of the little guys don't seem to make it to adulthood. I've seen hawks pick them off. I figured the Herons were as well, but have not witnessed it.
I think they do and reed warbler nestlings - I've even seen a photo of a grey heron with an adult reed warbler in its beak. In the UK, pike take many ducklings, too, and grebe chicks, so it seems that they are on a lot of menus.








