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Demographic Characteristics of Spotted Owls on the Roseburg District of the Bureau of Land Management, Roseburg, Oregon: 1985-1997
Completed
Accurate information is urgently needed on demographic and habitat characteristics of spotted owl (Strix occidentalis) populations. Without this information it is impossible to evaluate current population trends or to make predictions about the effects of various types of management on the owl. A preliminary analysis of banding data from five study areas indicated that all populations were declining. However, an analysis of actual changes in numbers of owls on the same five study areas indicated that density did not change significantly on four of the five areas. This discrepancy means that one or both methods of assessing population trends may be biased. The extent of this bias can only be determined by continued monitoring of owl populations. Some sources of bias may be reduced by collecting longer time series of data or by using different methods of parameter estimation. Our objectives for this study are: 1) elucidate the population ecology of the spotted owl on the Roseburg District of the Bureau of Land Management, to include population age structure and age specific birth, death, and reproductive rates; 2) determine annual survival rates of radio-marked juvenile spotted owls; 3) compare survival and reproductive rates of color-banded and radio-marked owls; 4) examine patterns of movement of dispersing juveniles, including distances moved and timing of dispersal; 5) estimate rates of juvenile emigration from the Roseburg Study Area; 6) document causes of juvenile mortality; and 7) document social integration of juveniles into the territorial population, to include age at pair formation and age at first breeding.
Anthony, R.G., Forsman, E.D., 2006, Status and trends in demography of Northern spotted owls, 1985-2003: Wildlife Society Wildlife Monographs no.163, v. 163, p. 1-163. [FullText] Catalog No: 1748 Reid, J.A., Forsman, E.D., Lint, J., 1996, Demography of Northern spotted owls on the Roseburg District of the Bureau of Land Management, Oregon: Studies in Avian Biology, v. 17, p. 59-66. [FullText] Catalog No: 1747
Haig, Susan M. - Supervisory Research Wildlife Biologist
Phone: 541-750-7482
Email: susan_haig@usgs.gov
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