March 1994 Abstracts 47 Spotted owls (Strix occidentalts) in western Washington PHANT. Department of Veterinary Anatomy, University of and Oregon are known to select older, unmanaged forests Saskatoon, Saskatoon, Saskatchewan S7N OWO Canada at spatial scales ranging from the foraging and roosting Population viability analyses are usually conducted on sites of individuals to the landscapes inhabited by local declining wildlife populations. One of the central goals of populations. But the current distribution of old forests is conservation biology is the restoration ofsuch populations inadequate to maintain a network of interacting local pop- It is therefore important to understand the dynamics of ulations. Thus, the success of any conservation strategy increasing populations. However, such populations are for spotted owls is contingent, in part, upon owls finding We relatively rare and little studied. present a population habitat in managed forests. Spotted owls are known to use viability analysis of an increasing urban merlin (Falco managed forest stands throughout the region for dispersal, columbarius) population that has been under study for over roosting, foraging, and breeding. Owls use managed forests 20 yr. Our hope is to provide a framework with which to in home ranges containing a mix of cover-types, from old- measure the success of future increases in threatened rap- growth to young plantations, and in ranges with little or tor populations. no old forest cover. Several homogeneous, managed-forest landscapes in the region contain numbers of reproductive owl pairs. However, the degree to which these varying The Breeding Ecology of Tawny Owl, Strix aluco, uses of managed forests suggests that spotted owls are IN Urban and Rural Environments; adapting to human-altered environments is unknown. In- A Comparative Study formation needed to address that question includes rela- Johnson, P.N. White Rose Cottage, Docking Road, Stan- tionships among: stand structure and owl use; character- hoe, Norfolk PE31 8QF UK. istics ofmanaged-forest landscapes and occupancy by owls; performance of owl populations in managed-forest land- Nesting boxes were erected in urban (N =17), suburban scapes; and the relationships among owl populations in (N = 8) and rural (N =11) environments during 1986 m old-forest and managed-forest landscapes. Ongoing inves- and around Bedford town, England. Breeding attempts by tigations of those aspects of owl ecology will strengthen tawny owl {Strix aluco) were monitored. Time of breeding our understanding ofthe nature ofspotted owls’ adaptation season, numbers of eggs and numbers of young fledged to managed forests and will support more effective con- were recorded, as was prey recorded in nesting sites. Pellets servation strategies. were analyzed from adults and fledged young. Dispersal of young was monitored by ringing and radiotelemetry. Vultures in a Man-made World During the study, avian prey species recorded were com- parable between environments, though micro-mammals Houston, D.C. Department of Zoology, Glasgow Uni- were absent in the diet of the urban population. Repro- versity, Glasgow G12 SQ.Q, Scotland ductive levels fluctuated in the rural and suburban envi- Scavenging birds differ from other raptors in their reaction ronments, but were constant at the urban sites. Therefore, to human disturbance to the environment. Some vulture the cycling of reproductive levels appears to be driven by species appear to benefit from human activities, and occur small mammal populations. Urban pairs did not breed in at higher densities in areas of high human population than seasons of low productivity in the rural environment. This in natural wildlife communities. But other species have effect affects the lifetime reproductive success of individ- shown serious population declines. In all species so far uals in the urban population which raise only half the studied the size of the food supply is not an important number of young in comparison with the other environ- factor in the decline of vulture species. Increased mortality ments. Time of breeding season was 4-5 wk advanced in rates are the major cause, and are particularly important the urban environment in comparison with rural birds because of the slow reproductive output of vulture pop- Young raised in the urban environment dispersed into the ulations. Human-induced causes of mortality for vultures rural environment. Competition for nesting boxes by other differ from those affecting most raptors, with poisoning species did not restrict the use of boxes by tawny owls in and bad power line design being the major factors. For- this study. tunately vulture populations respond well to management methods, and techniques for the recovery of vulture pop- Goshawk Adaptation to Deforestation in Europe ulations and reintroduction programs will be discussed. Kenward, R.E. Institute of Terrestrial Ecology, Furze- brook, Wareham BH20 5AS U.K. Population Viability Analysis of Urban Merlins Palearctic goshawks {Accipitergentilis) are often perceived James P.C. Royal Saskatchewan Museum, 2340 Albert as birds of the northern forests. In European taiga their Street, Regina, Saskatchewan S4P3V7Canada. I.G. War- densities are rarely as high as five breeding pairs per 100 KENTIN. Department ofZoological Research, Smithsonian km^, with nests in mature forest, and breeding diet pri- Institution, Washington, DC 20008 U.S.A. L.W. Oli- marily young grouse. Winter home ranges often exceed