Boreal owls range over a much larger area than do other owls of similar size  Scientists have hypothesized that <b> it is scarcity of prey that leads the owls to range so widely  </b>This hypothesis would be hard to confirm directly, since it is not possible to produce a sufficiently accurate count of the populations of small mammals inhabiting the forests where boreal owls live  Careful study of owl behavior has, however, shown that <b> boreal owls do range over larger areas when they live in regions where food of the sort eaten by small mammals is comparatively sparse
</b> This indicates that the scientists' hypothesis is not sheer speculation
The first describes a position that the argument opposes; the second states the main conclusion of the argument.