Boreal owls range over larger areas in regions where food of the sort eaten by small mammals is sparse than they do in regions where such food is abundant. After their young hatch, boreal owls must hunt more often than before in order to feed both themselves and their newly hatched young. Sometimes individual boreal owls hunt near a single location for many weeks at a time and do not range farther than a few hundred yards. The boreal owl requires less food, relative to its weight, than is required by members of other owl species.
Boreal owls range over a much larger area than do other owls of similar size. The reason for this behavior is probably that the small mammals on which owls feed are especially scarce in the forests where boreal owls live, and the relative scarcity of prey requires the owls to range more extensively to find sufficient food.
Which of the following, if true, most helps to confirm the explanation above?