I think it is fair to say that several of us had earlier agreed, although with reservations about details and degrees of artistic licence, that these etched birds are not accurate representations of a particular species. (
But I still think they are generally based on a heron of some type.)
For Ming's example shown above, Peejy mentioned "tendril thingies" and Ross commented on "trailing feathers" with a link to a type of bee-eater. As far as I know, trailing feathers, or tendril thingies, of most birds that have them are extensions of tail feathers. They do not sprout from below the body with the tail showing above them - which is how these mystery birds are shown. In Ming's example, there are certainly what appear to be legs below the body, but I believe those are actually parts of the background flora and the bird's legs are exactly as in the other examples. It's just an effect of having the bird set directly over background stuff, unlike the other examples where the bird is clear of the other elements.
Probably best to focus on the overall style of decoration rather than trying to pin things down to some country-specific creature.
