MONTANA STATE This "cover" page added by the Internet Archive for formatting purposes MONTANASTATELIBRARY v\ \ iLn\s-Tl ,v< i uvj 3 0864 0009 8234 1 m RESULTS OF BOREAL OWL (Aegolius funereus) SURVEYS ON THE JEFFERSON DIVISION OF THE LEWIS & CLARK NATIONAL FOREST by JOHN C. CARLSON Montana Natural Heritage Program 1515 East Sixth Avenue Helena, Montana 59620 for the W U.S.D.A. Forest Service "Lewis and Clark National Forest Great Falls, Montana 59403 Cooperative Challenge Cost Share Program <<j"',?*i x Montana Natural Heritage Program 9 Lewis and Clark National Forest COLLECTION DOCUMENTS STATE UOV 19 «97 UBRARY MONTANA STATE heuS^ntan^^o i; r~- <r : Cover drawing by John Carlson 1991 Montana Natural Heritage Program This document should be cited as follows: Carlson, J.C. 1991. Results of boreal owl (Aeqolius funereus) surveys on the Jefferson Division of the Lewis and Clark National Forest, Montana. Montana Natural Heritage Program. Helena, MT. 33 pp. ACKNOWLEDGEMENTS The financial support for this survey was provided by the Montana Natural Heritage Program and the Lewis and Clark National Forest through the Challenge Cost Share Program. I wish to thank Dave Genter, MTNHP, for allowing me to do this survey. Bob "Chief Two Hoots" Gliko, USFS, was my native guide and the best help I could have hoped for. Don Sasse, USFS district biologist was very helpful with suggestions and guidance during the survey. Kurt Pettersson, Julie Evans, Marie Karlson, Don Godtel, Don Sasse, Dana Fields, Dave Genter, Burt Lindler, Kristi DuBois, and Pat Finnegan all participated"' at one time or another in the survey - thank you. The entire staff at the Belt Creek Information Station was very helpful. The U.S. Forest Service provided me with a quiet place to stay during the survey and all the equipment we used. Thanks to Scott Jackson, John Malloy, and Dave Genter for reviewing this document and Margaret Beer for helping me with the computer. TABLE OF CONTENTS Page LIST OF TABLES AND FIGURES ii ACKNOWLEDGEMENTS iii SUMMARY 1 OBJECTIVES 2 INTRODUCTION 3 SURVEY AREA 5 METHODS 7 RESULTS . _. 10 DISCUSSION. 7 16 CONCLUSION AND RECOMMENDATIONS 13 REFERENCES 2 APPENDICES APPENDIX 1 22 APPENDIX 2 25 48 LIST OF TABLES NUMBER PAGE 1 - Owl survey routes and lengths 11 2 - Owl observations, 1991 12 LIST OF TABLES 1 - Distribution of the boreal owl by counties in Montana.... 2 - Map of survey area, Kings Hill Ranger District, Lewis and Clark National Forest 6 3 - Locations of survey routes within the study area, 1991... 11 ACKNOWLEDGEMENTS The financial support for this survey was provided by the Montana Natural Heritage Program and the Lev;is and Clark National Forest through the Challenge Cost Share Program. I wish to thank Dave Genter, MTNHP, for allowing me to do this survey. Bob "Chief Two Hoots" Gliko, USFS, was my native guide and the best help I could have hoped for. Don Sasse, USFS district biologist was very helpful with suggestions and guidance during the survey. Kurt Pettersson, Julie Evans, Marie Karlson, Don Godtel, Don Sasse, Dana Fields, Dave Genter, Burt Lindler, Kristi DuBois, and Pat Finnegan all participated"-at one time or another In the survey - thank you. The entire staff at the Belt Creek Information Station was very helpful. The U.S. Forest Service provided me with a quiet place to stay during the survey and all the equipment we used. Thanks to Scott Jackson, John Malloy, and Dave Genter for reviewing this document and Margaret Beer for helping me with the computer. 111 SUMMARY A survey for boreal owls was conducted on the Lewis and Clark National Forest in the Little Belt Mountains of central Montana during February and March of 1991. The call playback method was used to survey for owls on 19 nights. A total of 13 survey routes were established, encompassing 87 calling points and 70.2 miles. Some routes were surveyed more than once for a total of 88.5 miles. All owl observations were recorded and mapped. Habitat classifications were- obtained from timber typing maps for all boreal owl locations. Boreal owls were heard at 8 calling points, represented 6 individuals. All but one were located in lodgepole pine (Pinus contorta) timber types. The other was in a whitebark pine Pinus albicaulis timber type. All were located between 6400 ( ) ft. and 8088 ft. in elevation. Other owl species located, in order of abundance, were northern saw-whet Aegolius acadius great ( ) , horned Bubo virginianus barred Strix varia great gray Strix ( ) , ( ) , ( nebulosa and a western screech owl (Otus kennicottii Surveys ) , ) . are recommended for at least 3 more years in the Little Belt Mountains to accurately determine the population characteristics and habitat used by boreal owls. OBJECTIVES The 1991 surveys for boreal owls were initiated to document the occurrence of, and habitat used by boreal owls on the Jefferson Division of the Lewis and Clark National Forest. Similar data were to be gathered for other owl species present. These data will assist in forest planning and will contribute in the assessment of distribution, population dynamics and viability of the boreal owl on the Lewis and Clark National Forest. INTRODUCTION The boreal owl Aegolius funereus is a highly nocturnal owl ( ) which inhabits northern hemisphere coniferous forests around the world. They are generally 21.5 to 30.5 cm long (Farrand 1983) and weigh 100-140 gm (Earhart and Johnson 1970) Boreal owls are small, . brown owls with many white spots on their crown, nape, and back. Yellow eyes and a yellowish bill are framed by distinctive black facial frames which are spotted with many small white spots. Their white underparts are streaked with chocolate brown. Juveniles are dark chocolate brown with white spots across the back and white eyebrows and cheek spots. Boreal owls are secondary cavity nesters, usually occupying cavities constructed by the northern flicker Colaptes auratus) or ( pileated woodpecker Dryocopus pileatus Boreal owls will also use ( ) . artificial nesting boxes (D. Center per. comm.). Boreal owls are territorial and a nesting pair will actively defend the area around the nest site (D. Genter per. comm.). After the courtship in March and April, 4 to 6 pure white eggs are laid. The eggs are incubated for 27-28 days by the female and the young fledge 28-33 days after hatching (Terres 1980) Boreal owls prey mainly on small mammals, . primarily redback voles Clethrionomys gapperi but also pocket ( ) gophers Thamomys talpoides shrews (Sorex spp.), and deer mice ( ) . Peromvscus maniculatus Some insects and birds are also eaten ( ) . (Hayward et al. 1987). The owls are generally secretive throughout the year, residing