racing pigeon ……. That was my thought too on balance of probability. Although the beak as described hardly matches a pigeon. To which I would add it is common for the keratin of the beak to break off the bony base of a bird’s skeleton and decompose once a bird has died and the body exposed to the elements. This can make the beak look big. Hard to imagine though how the leg / feet skeleton of any dead bird could be confused between a pigeon and a Black-tailed Native Hen. But then maybe not so easy if you are not familiar with anatomy or seeing dead birds…….
Philip