For example, birds may expend more of their reserves on thermoregulation if they spend the night exposed to the wind on a song post than if they are in a sheltered roost site.

No, we have knowledge of no world but yours, though for us it holds no sunlight, no warmth, no music, no laughter, no song of birds, nor any companionship.

To sort out this seeming discrepancy, Elizabeth Dumont of the University of Massachusetts Amherst studied the skulls and limb bones of song birds, rodents and bats.