Skip to page content
USDA Forest Service
  
Treesearch

Research & Development Treesearch

 
Treesearch Home
About Treesearch
Contact Us
Research & Development
Forest Products Lab
International Institute of Tropical Forestry
Northern
Pacific Northwest
Pacific Southwest
Rocky Mountain
Southern Research Station
Help
 

Science.gov - We Participate


USA.gov  Government Made Easy


Global Forest Information Service

US Forest Service
P.O. Box 96090
Washington, D.C.
20090-6090

(202) 205-8333

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

Publication Information

View PDF (511 KB bytes)

Title: Influence of Survey Length and Radius Size on Grassland Bird Surveys by Point Counts at Williams Lake, British Columbia

Author: Savard, Jean-Pierre L.; Hooper, Tracey D.;

Date: 1995

Source: In: Ralph, C. John; Sauer, John R.; Droege, Sam, technical editors. 1995. Monitoring bird populations by point counts. Gen. Tech. Rep. PSW-GTR-149. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: p. 57-62

Publication Series: General Technical Report (GTR)

   Note: This article is part of a larger document. View the larger document

Description: We examine the effect of survey length and radius on the results of point count surveys for grassland birds at Williams Lake, British Columbia. Four- and 8-minute counts detected on average 68 percent and 85 percent of the number of birds detected during 12-minute counts. The most efficient sampling duration was 4 minutes, as long as travel time between points was under 15 minutes. Density estimates derived from 4-minute counts were significantly lower than 12-minute counts for most radius sizes. A larger radius yielded a larger number of detections but not always proportionally with the increase in area. This resulted in lower estimated density with an increase in radius size, especially when using maximum values at a given point. However for the Horned Lark (Emeophilia alpestris), the most abundant species, estimates of densities derived from individual counts did not differ significantly with radius size. A 100-m radius yielded nearly as many detections as an unlimited radius for most species, suggesting that it may be the most efficient radius to use in open habitats.

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.

XML: View XML

Citation:


Savard, Jean-Pierre L.; Hooper, Tracey D. 1995. Influence of Survey Length and Radius Size on Grassland Bird Surveys by Point Counts at Williams Lake, British Columbia. In: Ralph, C. John; Sauer, John R.; Droege, Sam, technical editors. 1995. Monitoring bird populations by point counts. Gen. Tech. Rep. PSW-GTR-149. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: p. 57-62

 


 [ 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.