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 (2.8 MB bytes)

Title: Diets and foraging behavior of northern spotted owls in Oregon.

Author: Forsman, Eric D.; Anthony, Robert G.; Meslow, E. Charles; Zabel, Cynthia J.;

Date: 2004

Source: J. Raptor Res. 38(3): 214-230

Publication Series: Scientific Journal (JRNL)

Description: We describe local, regional, and annual variation in diets of northern Spotted Owls (Strix occidaatalis caurina) in Oregon based on 24497 prey collected at 1118 owl territories in 1970-2003. The sample included 91.5% mammals, 4.3% birds, 4.1% insects, and 0.1% other prey. The diet included 2131 species, including 49 mammals, 41 birds, 3 reptiles, 1 frog, 1 crayfish, 1 scorpion, 2 snails, and 33 species of insects. On average, 91.9 ± 0.3% (SE) of prey in the diet were nocturnal animals, 3.3 ± 0.2% were diurnal, and 4.8 ± 0.2% were active both day and night. Of the prey captured, 50.5 ± 0.8% were arboreal, 18.7 ± 0.7% were scansorial, 4.8 ± 0.2% were aerial, and 26.0 ± 0.7% were terrestrial. Mean mass of prey was 116.6 ± 6.5 g. Diets varied among owl territories, geographic regions, and years; but were generally dominated by four to six species of nocturnal mammals, including northern flying squirrels (Glaucomys sabrinus), woodrats (Neotoma fuscipes and N. cinerea), red tree voles (Arborimus longicaudus), western red-backed voles (Clethnonomys californicus), deer mice (Peromyscus maniculatus), or gophers (Thomomys spp.). Estimates of dietary evenness were low, indicating diets dominated by a few species of mammals. Forest management practices that produce healthy populations of arboreal and scansorial mammals such as flying squirrels, woodrats, and red tree voles should benefit northern Spotted Owls in Oregon and Washington.

Keywords: northern spotted owl, Strix occidentalis caurina, diet, prey selection, northern flying squirrel, Glaucomys sabrinus, red tree vole, Arborimus longicaudus

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.



Forsman, Eric D.; Anthony, Robert G.; Meslow, E. Charles; Zabel, Cynthia J. 2004. Diets and foraging behavior of northern spotted owls in Oregon. J. Raptor Res. 38(3): 214-230


 [ 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.