FOOD HABITS AND TROPHIC ATTRIBUTES OF THE MAGELLANIC HORNED OWL (BUBO MAGELLANICUS) IN PATAGONIAN STEPPE, SOUTHERNMOST CHILE

Abstract

For most of southern South America, the food habits of Magellanic Horned owls (Bubo magellanicus) are well known. In Chile, several researchers have reported the owl’s diet in northern xerophytic environments, as well as subpolar forests; however, other than a short note on the owls’ summer diet in Punta Dungeness, no major studies have documented the food habits of Magellanic Horned owls in the Chilean Patagonian steppe. Based on 278 fresh pellets, we reported the food habits of owls inhabiting two sites located at > 52°S in the southernmost Patagonian steppe in continental Chile, and compared our findings with those reported for owls inhabiting eight localities from 39 to 52°S in the Argentinean Patagonian steppe. Our results indicate that in Patagonian steppe environments of both Argentina and Chile, the Magellanic Horned Owl is a generalist predator, which consumes whatever prey available, ranging in size from inver- tebrates to introduced juvenile lagomorphs. Because all five major vertebrate prey here reported (Abrothrix olivacea, Loxodontomys micropus, Microcavia australis, Reithrodon auritus, Lepus europaeus) are broadly distributed in the Argentinean Patagonian steppe and occur abundantly from 36°S southwards to the Strait of Magellan and Isla Grande de Tierra del Fuego, their generalized occurrence as prey does not allow for expression of latitudinal trends in species composition in the owl’s diet.