The Winnie-the-Pooh stories are an interesting mix of realism and fantasy. Donkeys do eat thistles (according to this website, they are the only animals that do), pigs do eat acorns (according to this website, they fatten up fastest from eating acorns), and of course we know bears like honey. But a kangaroo pouch doesn’t look much like the patch-type pocket Kanga has, and I very much doubt a young pig could manage to get in. For the most part, the animals are anthopomorphized, and tell us a great deal more about human behavior than animal behavior.
Perhaps young bears, though, are prone to sticking their heads into food containers and then getting stuck in them. At least this one did. I’ve never seen a bird feeder quite like that one, so I don’t know what sort of food it was trying to get at. Being an omnivore, I suppose it would be interested in any sort of food, perhaps even being drawn to the scent of the birds that had fed there.
At least it had Mom around, and didn’t have to blunder around afraid of falling into a Heffalump pit.