United States
Department of
Agriculture
Forest Service
Paciflc Southwest
Research Station
General Technical
Repott PSW-GTR-133
The California Spotted Owl:
A Technical Assessment
of Its Current Status
Verner, Jared; McKelvey, KevinS.; Noon, Barry R.; Gutikrrez, R. J.; Gould. Gordon I.. Jr.; Beck. Thomas W.,Technical
Coordinators. 1992. T h e California spotted owl: a technical assessment of its current slatus. Gen. Tech. Rep.
PSW-GTR-133. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; 285 p.
This renort is based an the Final Renart submitted on Mav, 8.. 1992 bv the Technical Assessment Team to the
interagency Steering Committee for the California Spotted Owl Assessment. The 13 chapters cover the assessment of
thecurrent status of theCaliforniaspotted owl, its biology and habitat use, and forests wherethe subsoecies occurs in the
~
~~
Rerrievol Terns: Strix occidenlalis occidomlis, habitat attributes, old-growth, resource management, Sierra Nevada,
southern California
Technical Coordinators:
J a r e d Verner, a research wildlife biologist, is Project Leader-Wildlife Monitoring and Range Research, Pacific
Southwest Research Station, USDA Forest Service, Fresno. California. and the Technical Assessmenl Team Leader
I<e\in S. \lcKrlvr.y 1s %: ~ M # rb cw I o ~ # s~t N I thc
I St,x.on. 11111 s t . ~ l ~ ~in: dAKIL C d l i Harq K. U w n . 3 ir.e,r:l~
~~~.
Arcdld. R. J. ( i a t i C r r r ~i,
u,tld.lfi. hmlogtrt wtl~the Stat~ou1 % Prole;! l.c.dcr-hnoer Wildlife I n r c . ~ i c t Rc,carcll.
professor ofwildlife, Humboldt State University, Arcata. Gordon I. Gould, Jr., is a nongame wildlife biologist with the
California Depanment of Fish and Game, Sacmmenta. Thomas W. Beck is a forcst biologist with the Stanislaus
National Forest, USDA Forest S"&ce, Sonora, Calif.
Cover-:Photographs by John S. Senser, Stanislaus National Forest, Mi-Wuk Village, Calif.
Publisher:
Pacific Southwest Research Station
Albany, California
(Mailing address: P.O. Box 245, Berkeley, California 94701-0245
Telephone: 510-559-6300)
July 1992
A Technical Assessment of Its Current Status
Technical Coordinators:
Jared Verner
Kevin S. McKelvey
Barry R. Noon
R. J. Gutierrez
Gordon I. Gould, Jr.
Thomas W. Beck
Contents
Part I: Where We Are Now, and Where We Should Go Next
Chapter 1.
Assessment of lhe current status of the California spotted owl, with recommendations
for management ......................................................................................................................
Jared Verner, Kevin S. McKelvey, Barry R. Noon, R. J . Cutidrl-ez,Gordon I. Gould, Jr..
3
and Thomas W. Beck
Chapter 2.
Future directions for the California spotted owl effort .................................................................. 27
Jared Ver-ner and Roberl J. Taylor
Part IT: About the Owl
Chapter 3.
Background and the current management situation for the California spotted owl
Thomas W. Beck and Gordon I.Gould, Jr.
........................
37
Chapter 4.
The California spotted owl: general biology and ecological relations ........................
.
.
.............55
Jared Verrzer,R. J. Girtidrrez, and Gordon I.Could, Jr.
Chapter 5.
Habitat relations of the California spotted owl ...............................................................................
79
R. J. Gutidrr-ez,Jared Verner, Kevin S. McKelvey, Barry R. Noon,George N . Steger, Douglas R.
Call, William S. LaHaye, Bruce B . Bingham, and John S. Senser
Color Photograph Section ........................
.
................................................................................ 99
USDA Forest Serv~ceGen Tech Rep PSW-GTR-I33 1992
Contents
Chapter 6.
Home-range size and habitat-use patterns of California spotled owls in the Sierra Nevada .........149
Cynthia J. Zabel, George N. Steger, Kevin S. McKelvey, Gary P. Eberlein,
Barry R. Noon, andJared Verner
Chapter 7.
Patterns of habitat use by California spotted owls in logged forests of the northern
.
..........................................................................165
Sierra Nevada .............................
Cynthia J . Zabel, Kevin S. McKelvey, and James D. Johnston
Chapter 8.
Estimates of demographic parameters and rates of population change ........................................
175
Barry R. Noon, Kevin S. McKelvey, Daryl W. Lutz, William S. LaHaye,
R. J. Gutiirrez, and Christine A. Moen
Chapter 9.
Stability properties of the spotted owl metapopulation in southern California .............................I87
Barry R. Noon and Kevin S. McKelvey
Chapter 10.
General biology of major prey species of the California spotted owl
Daniel F. Williams,Jared Verner, Howard F. Sakal, and Jeffrey R Waters
207
Part HI: About Forests and Forest Management
Chapter 11.
Historical perspectives on forests of the Sierra Nevada and the Transverse Ranges of southern
. ................225
California: forest conditions at the turn of the century
Kevin S. McKelvey and James D. Johnston
Chapter 12.
Fire and fuels management in relation to owl habitat in forests of the Sierra Nevada and
. .
southern Cal~forn~a
....................
.
.
..................................................................................
247
C. Phillip Weatherspoon,Susan J. Husari, and Jan W . van Wagtendonk
Chapter 13.
. .................................................261
Projected trends in owl habitat
Kevin S. McKelvey and C. Phillip Weather-spoon
Appendices
Marlene B. Verner, Compile!Appendix A-Technical
Assessment Team and Chronology of Activities ..................................277
Appendix B--Glossary
...............................................................................................................
279
Appendix C S p e c i e s List
283
Appendix D-Authors
285
and Their Chapters
USDA Forest Service Gen. Tech. Rep. PSW-GTR-133. 1992.