VARIATION IN THE MALE TERRITORIAL HOOT OF THE TAWNY OWL STRIX-ALUCO IN 3 ENGLISH POPULATIONS

Little is known about owl song. We made sonagrams of the territorial c alls of 50 male Tawny Owls Strix aluco from three different areas. Six temporal and four frequency measures of the calls were recorded from the sonagrams, The measures of the calls were then subjected to analys is to try to separate between individual owls and between owls from di fferent areas. We also looked for similarities between calls of neighb ouring owls and for any effect of habitat on owl hoots. Individual owl s were separated on the basis of their hoots with a high degree of suc cess (98.6% overall), and there were significant differences between a reas. Differences were found between calls in woodland and farmland ha bitats, but these differences were not in the direction expected to in crease sound transmission, Calls of neighbouring owls did not resemble each other more than calls from owls that were not in vocal contact, implying that if calls are learned by Tawny Owls, they are learned bef ore dispersal.