Rocky Mountain Research Station Publications
RMRS Online Publication
RM-GTR-253: Flammulated, boreal, and great gray owls in the United
States: A technical conservation assessment
Hayward, G. D. and J. Verner, tech. editors. 1994. Flammulated, boreal, and great gray owls in the United States: A technical conservation assessment. Gen. Tech. Rep. RM-253. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 214 p. 3 Maps.
Flammulated (Otus flammeolus), boreal (Aegolius funereus), and great gray (Strix nebulosa) owls occur over a broad portion of North America and each is designated as a "sensitive species" in four or more USDA Forest Service regions. The insectivorous flammulated owl is a neotropical migrant requiring suitable wintering habitat in the extreme southwestern United States, Mexico, and Central America as well as breeding habitat in the mountains of the western United States. Flammulated owls breed predominantly in yellow-pine (Pinus ponderosa and Pinus jeffreyi) forests and are cavity nesters. The mature and older ponderosa pine forests used as breeding habitat by flammulated owls have changed during the past century due to fire management and timber harvest. In contrast, the boreal owl is a nomadic, small mammal specialist that occurs as an "island" species occupying subalpine and boreal forests. Movements among populations are probably important to boreal owl persistence, and coordinated management of disjunct populations in different Forest Service regions may be important. While the boreal owl's high altitude spruce-fir forests have remained relatively undisturbed in the past, they are coming under increasing harvest pressure as the stock of lower elevation older stands are depleted or reserved. Great gray owls in the western United States occur in mid to high elevation conifer forests. These owls usually nest in mature and older forest stands using existing raptor nests or tops of broken trees and snags for a nest platform. The species' requirement of a secure nesting platform leads to one potential ecological limitation on population size. Prey availability is the other factor thought to limit populations. Flammulated and boreal owls may face significant conservation problems in the absence of conservation planning. Both owls are associated with older forest habitats. Limited research on these species indicates that their demography and life history coupled with their fairly narrow habitat associations make them vulnerable to habitat change. Current forest management practices in many areas (i.e., stand replacement systems) remove quality habitat for these species. Therefore, on at least a local basis, persistence of these species could be in jeopardy, even in the short term. Long-term concerns are greater because the habitats that seem most important to these species require one to two centuries to regenerate. Furthermore, the population biology of both species necessitates across-region planning to facilitate effective conservation planning. Based on limited information, the persistence of great gray owl populations in the United States over both the short and long-term is more certain. Great gray owl foraging habitat use is more compatible with current forest management practices. Our understanding of the ecology and biology of these three species is not sufficient to produce a conclusive assessment of their conservation status. The enclosed assessments, however, give a sufficiently clear picture of each owl's status and the dynamics of important forest habitats to influence management and research decisions. It is clear that development of conservation strategies would aid management but current knowledge of these species is insufficient to produce such a specific document.
Keywords: flammulated owl, boreal owl, great gray owl, Otus flammeolus, Aegolius funereus, Strix nebulosa, habitat relationships, old growth, forest dynamics, ponderosa pine forest, spruce-fir forest, conservation
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http://www.fs.fed.us/rm/pubs_rm/rm_gtr253.pdf
PDF File Size: 30.1 MBDownload RM-GTR-253 by chapters
Contents
PDF File Size: 560 KPart I: Introduction
Chapter 1. Approach: The flammulated, boreal, and great gray owl assessments
Gregory D. Hayward
PDF File Size: 290 KChapter 2. Methods and terminology used with studies of habitat associations
D. Archibald McCallum
PDF File Size: 415 KPart II: Flammulated Owls
Chapter 3. Current management situation: Flammulated owls
Jon Verner
PDF File Size: 280 KChapter 4. Review of technical knowledge: Flammulated owls
D. Archibald McCallum
PDF File Size: 3.4 MBChapter 5. Dynamics of ponderosa and Jeffrey pine forests
Penelope Morgan
PDF File Size: 2.7 MBChapter 6. Conservation status of flammulated owls in the United States
D. Archibald McCallum
PDF File Size: 590 KChapter 7. Information needs: Flammulated owls
D. Archibald McCallum
PDF File Size: 680 KPart III: Boreal Owls
Chapter 8. Current management situation: Boreal owls
Jon Verner
PDF File Size: 295 KChapter 9. Review of technical knowledge: Boreal owls
Gregory D. Hayward
PDF File Size: 3.5 MBChapter 10. Dynamics of subalpine forests
Dennis H. Knight
PDF File Size: 1.1 MBChapter 11. Conservation status of boreal owls in the United States
Gregory D . Hayward
PDF File Size: 960 KChapter 12. Information needs: Boreal owls
Gregory D. Hayward
PDF File Size: 640 KPart IV: Great Gray Owls
Chapter 13. Current management situation: Great gray owls
Jon Verner
PDF File Size: 250 KChapter 14. Review of technical knowledge: Great gray owls
James R. Duncan and Patricia H . Hayward
PDF File Size: 1.7 MBChapter 15. Dynamics of forest communities used by great gray owls
James R. Habeck
PDF File Size: 3.1 MBChapter 16. Conservation status of great gray owls in the United States
Gregory D. Hayward
PDF File Size: 535 KChapter 17. Information needs: Great gray owls
Gregory D. Hayward
PDF File Size: 490 KAppendix A: About the authors
PDF File Size: 210 KMaps
PDF File Size: 8.5 MBMap 1. Flammulated Owl Locations and Distribution of Associated Vegetative Ecosystems in the United States
Map 2. Boreal Owl Locations and Distribution of Associated Vegetative Ecosystems in the United States
Map 2a. Addendum to Map 2
Map 3. Great Gray Owl Locations in the United States
Title: RM-GTR-253:
Flammulated, boreal, and great gray owls in the United States:
A technical conservation assessment
Electronic Publish Date: October 9, 2007
Last Update: October
9, 2007