Many years ago, my grandparents, who lived at Upwey, would occasionally put out strips of liver for the kookaburras. I remember being told (must have been about 1950) that sometimes they would cough up less desirable stuff they had eaten to enjoy the liver. I now believe this was regurgitation of undigested remains, kookaburras being one species that does this routinely. Sometimes a bird will need to regurgitate obstructive remains to take in more food. My best example of this is a Dusky Woodswallow on a powerline, clutching a European Wasp in one foot while it ejected a large pellet of insect remains. (Photo from last June, Canberra)
This brings us of course to the Pied Currawong, the regurgitative habits of which have been discussed on more than one chatline. Messy, crumbly pellets can create a problem at backyard watering sites that the bird visits, presumably to drink, such as dogs’ water bowls, bird baths and ornamental water features. Australia’s champion regurgitator I would say (passerine division). Indeed it might be a contender for the world title, although I believe the American Robin has a similar reputation.
There is a photo. I might just be able to fit it in under the limit if I reduce the woodswallow one. GD