Pacific Southwest

Title: Effects of observers using different methods upon the total population estimates of two resident island birds

Author: Conant, Sheila; Collins, Mark S.; Ralph, C. John

Date: 1981

Source: Studies in Avian Biology No. 6:377-381

Description: During a 5-week study of the Nihoa Millerbird and Nihoa Finch, we censused birds using these techniques: two line transect methods, a variable-distance circular plot method, and spot-mapping of territories (millerbirds only). Densities derived from these methods varied greatly. Due to differences in behavior, it appeared that the two species reacted differently to the observer. Millerbirds appeared to be attracted to a moving observer, perhaps to forage on insects; finches appeared to be attracted to a stationary observer in order to feed on seabird eggs temporarily abandoned during the count. Although these behaviors may be unusual, they dramatically demonstrate that no single census method will suffice for all species. The method that assures the least observer effect will provide the most accurate population estimate.

Keywords: 

View and Print this Publication (302 KB)

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.

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

Citation

Conant, Sheila; Collins, Mark S.; Ralph, C. John  1981.  Effects of observers using different methods upon the total population estimates of two resident island birds.   Studies in Avian Biology No. 6:377-381.