Skip to page content
USDA Forest Service

Research & Development Treesearch

Treesearch Home
About Treesearch
Contact Us
Research & Development
Forest Products Lab
International Institute of Tropical Forestry
Pacific Northwest
Pacific Southwest
Rocky Mountain
Southern Research Station
Help - We Participate  Government Made Easy

Global Forest Information Service

US Forest Service
P.O. Box 96090
Washington, D.C.

(202) 205-8333

You are here: Home / Search / Publication Information
Bookmark and Share

Publication Information

View PDF (138 KB)

Title: Estimating population size with correlated sampling unit estimates

Author: Bowden, David C.; White, Gary C.; Franklin, Alan B.; Ganey, Joseph L.;

Date: 2003

Source: Journal of Wildlife Management. 67(1): 1-10.

Publication Series: Scientific Journal (JRNL)

Description: Finite population sampling theory is useful in estimating total population size (abundance) from abundance estimates of each sampled unit (quadrat). We develop estimators that allow correlated quadrat abundance estimates, even for quadrats in different sampling strata. Correlated quadrat abundance estimates based on mark–recapture or distance sampling methods occur when data are pooled across quadrats to estimate, for example, capture probability parameters or sighting functions. When only minimal information is available from each quadrat, pooling of data across quadrats may be necessary to efficiently estimate capture probabilities or sighting functions. We further include information from a quadrat-based auxiliary variable to more precisely estimate total population size via a ratio estimator. We also provide variance estimators for the difference between or the ratio of 2 abundance estimates, taken at different times. We present an example based on estimating the number of Mexican spotted owls (Strix occidentalis lucida) in the Upper Gila Mountains Recovery Unit, Arizona and New Mexico, USA. Owl abundance for each quadrat was estimated with a Huggins 4-pass mark–resight population estimator, but with initial capture and resighting probabilities modeled in common across all sample quadrats. Pooling mark–resight data across quadrats was necessary because few owls were marked on individual quadrats to estimate quadrat-specific capture probabilities. Model-based estimates of owl abundance for each quadrat necessitated variance estimation procedures that take into account correlated quadrat estimates. An auxiliary variable relating to topographic roughness of sampled quadrats provided a useful covariate for a ratio estimator.

Keywords: Arizona, closed population estimation, finite population sample theory, Huggins estimator, mark–recapture, mark–resight, Mexican spotted owl, New Mexico, program MARK, ratio estimator, Strix occidentalis lucida

Publication Notes:

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.



Bowden, David C.; White, Gary C.; Franklin, Alan B.; Ganey, Joseph L. 2003. Estimating population size with correlated sampling unit estimates. Journal of Wildlife Management. 67(1): 1-10.


 [ Get Acrobat ]  Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.