Recovery Plan for the Northern Spotted Owl - DRAFT
Share Embed Flag
Download ePaper

Recovery Plan for the Northern Spotted Owl - DRAFT

Recovery Plan for the Northern Spotted Owl - DRAFT Recovery Plan for the Northern Spotted Owl - DRAFT

soda.sou.edu
from soda.sou.edu More from this publisher
10.07.2015 Views

320

1. IntroductionThe 1990 Status Review Northern Spotted Owl (USDI 1990) provided estimatesof the rate of population change for populations of northern spotted owls innorthern California (Willow Creek and surrounding regional study area) andsouthern Oregon (the Roseburg study area). The population of resident femaleowls in these areas was shown to be declining at a significant rate. By the fallof 1991, there were 2 additional years of capture-recapture data on these twopopulations, and three new areas (Medford in southern Oregon, H.J. Andrewsnear Corvallis, Oregon, and the Olympic Peninsula in northwestern Washington)had sufficient years of capture-recapture data to warrant an intensiveanalysis (Table C. 1). More than 2,000 owls had been marked and theresighting probability for adult females was approximately 0.8 to 0.9 percent.This appendix provides estimates of the rate of population change of resident,territorial females in these five large study areas. Analysis methods (e.g.,model building, model selection, tests of model fit, parameter estimation, andinference procedures concerning the rate of population change) are those usedin USDI (1990) with some extensions. The key references on methodology areBurnham and Anderson (In Press) and Lebreton et al. In Press). The analysesof data were done during September-October 1991, during two intensiveworkshops held in Fort Collins, Colorado. The analyses were completed by sixbiologists working on the northern spotted owl-two French scientists, twoprofessors from Colorado State University with special expertise in the analysisof capture-recapture data, and two U.S. Fish and Wildlife Service employeesfrom the Colorado Cooperative Fish and Wildlife Research Unit.2. Results and DiscussionTwo parameters are of critical interest; A = finite (i.e., annual) rate of change inthe size of the population of females, and $ = annual probability of survival ofadult females. Maximum likelihood estimates of these parameters are shownas A and $, respectively, along with estimates of their precision (i.e., se (A) ande ($)). If the number of resident females is 'stationary," then X = 1, while if thepopulation is declining, then X < 1. Thus, there is interest in testing the nullhypothesis Ho: X < 1 against the alternative hypothesis Ha: X < 1. Proper estimationof X answers the critical question, "Have the resident, territorial femalesreplaced themselves?"/Table C.1. Summary information on the five demographic study areas.TotalApproximate Size Years of IndividualsName of Study Area Marking MarkedNorthwest California 4,000 1985-91 400H.J. Andrews (western Oregon) 116 1987-91 358Medford (southwestern Oregon) 4,050 1985-91 703Roseburg (southwestern Oregon) 1,700 1985-91 589Olympic Peninsula (northwestern Washington) 965 1987-91 302321

320

logo

products

Resources

Company

Terms of service
Privacy policy
Cookie policy
Cookie settings
Imprint
Change language
Made with love in Switzerland
© 2024 Yumpu.com all rights reserved

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!