Garden young uns

"It's rare to see them venture out from under the shrubbery but the little un sunbathes in the middle of the lawn."

Less worldly wise. Predators rely on this.

(I used to have a collection of racing pigeon rings collected from beneath a peregrine nest. I'd suggest that there was a very strong correlation in the age indicated from the rings. Obviously fewer older birds are involved in the racing, but they did appear to be much more worldly wise.)