Like so many other groups in the Philippines, owls come in an amazing variety of sizes and habits, often with five or six species living in the same area. The smallest are only seven inches long, about the size of a large thrush such as the American robin. These little birds feed on a seemingly unlikely but abundant prey: beetles and crickets. At the other end of the scale is the Philippine eagle-owl (Bubo philippensis), one of the largest owls in the world, with a wingspan of about about 48 inches (120 centimeters). What the eagle-owl eats is a mystery; the species is so poorly known that not even this basic information is available. We do know, however, that most observations of the species have been made in lowland forest near or beside rivers. Since a related species in Malaysia feeds on fish, Philippine eagle-owl mightalso.
The small species of owls have been conspicuous and pleasant companions to us on many nights in the Philippine forest, their clear whistling and hooting calls softly sounding in the quiet night air. Most of the small owls occur in a range of old-growth forest habitats, and some are able to survive in fairly small forest patches. Still, four Philippine species are now vulnerable to extinction due to massive habitat destruction. The Philippine eagle-owl and the lesser eagle-owl (Mimizuku guerneyi) are in even worse shape because they live only in lowland forest, and their large size requires that they have large tracts of forest to maintain populations. If rivers are indeed a crucial part of their habitat, that is bad news for the owls, because old-growth forest along rivers is now especiallyrare. Of course, protecting habitat for the owls would also benefit the people who live downstream, since protecting forest along rivers would help control floods.
Original URL: http://archive.fieldmuseum.org/vanishing_treasures/V_EagleOwl.htm