Grenier and Nelson 



Chapter 19 



Inland Habitat Associations in Oregon 



However, nests may have been easier to find by observers 

 in situations where tree densities were low. In addition, 

 very low canopy cover may allow higher predation rates 

 (see Nelson and Hamer, this volume b). Conclusions about 

 appropriate canopy cover levels for nesting murrelets cannot 

 be made without further research on nesting success and 

 with larger sample sizes. 



The characteristics of nests in Oregon were similar to 

 those described by others in Alaska, British Columbia, 

 Washington, and California (Hamer and Nelson, this volume 

 b; Jordan and Hughes, in press; Manley and Kelson, in 

 press: Naslund 1993b; Naslund and others, in press; Nelson 

 and Hamer 1992; Singer and others 1991, in press). Excluding 

 Alaska, all nests have been located in trees > 88 cm in 

 diameter and > 1 8 m in height (n = 47) (Hamer and Nelson, 

 this volume b). 



Conclusions 



Our results support previous studies and observations 

 that murrelets use older forests or forests with old-growth 

 characteristics. Key habitat characteristics of occupied sites 

 were tree height, density of dominant (or remnant) trees, 

 diameter and percent cover of midstory and understory trees, 

 and canopy cover. Nests were located in large trees with 

 large platforms and high vertical canopy cover. 



Additional detailed information on the characteristics 

 (platform availability, abundance of mistletoe and moss) 

 of Marbled Murrelet habitat are needed to refine the 

 definition of suitable habitat in Oregon. Studies designed 

 to collect habitat data specific to murrelets from plots in 

 the forest (including the key variables listed above) are 

 needed. In addition, further investigations into plant 

 associations are recommended. 



There are limitations to describing murrelet habitat on 

 the basis of occupancy, presence, or abundance. We can 

 describe the general features of habitat used by this species; 

 however use of these measures as a means for determining 

 habitat quality, suitability, or preference may not be valid, 

 especially in patchy habitats (Fretwell and Lucas 1969, Hanski 

 1982, Van Home 1983). Models developed to measure habitat 

 quality and suitability have included components of density, 

 reproductive rates, genetic contribution of adults to the next 

 generation, and survival of adults and juveniles (Fretwell 

 and Lucas 1969. Van Home 1983). A more adequate means 

 of evaluating habitat suitability will be to explore the 

 relationship between reproductive success, and habitat and 



landscape characteristics. This should be an emphasis of 

 future research projects. 



In addition, caution is advised in using our description 

 of occupied sites from the state and federal databases. These 

 data were not collected to describe murrelet habitat, and our 

 analysis was retrospective. Occupied sites also were not 

 selected randomly. Therefore, occupied site characteristics 

 may be an artifact of how stands were chosen for timber 

 harvesting and thus murrelet surveying, and which habitat 

 variables were measured. Future research should include 

 collecting data specific to biology of murrelets, e.g., 

 availability of platforms, moss, and mistletoe. 



Acknowledgments 



Funding for this project was provided by the Oregon 

 Department of Fish and Wildlife, Nongame Wildlife Research 

 Program; the USDI Bureau of Land Management, Salem 

 and Coos Bay Districts; the U.S. Fish and Wildlife Service, 

 U.S. Department of Interior; and the USDA Forest Service. 

 Special thanks go to G. Gunderson, W. Logan, L. Mangan, 

 M. Nugent, C. Puchy, M. Raphael for their cooperation, 

 support, and advice. 



We also thank S. Andrews, C. Bickford, R. Davis, S. 

 Madsen, C. McCain, C. Wettstein of the Siuslaw National 

 Forest, B. Reagan, B. Reich, K. Graham of the Oregon 

 Department of Forestry, and N. Allen, C. Bruce, G. Sieglitz of 

 the Oregon Department of Fish and Wildlife for access to their 

 databases. Data collection and management were conducted 

 by D. Elliott, J. Hardin, A. Hubbard, B. Peck, M. Pope, M. and 

 J. Raisinghani. J. Reams, J. Rosenthal, T. Ross, M. Shaughnessy, 

 and J. Wells. Additional logistical support was provided by 

 D. Crannell, J. Guetterman, J. Heeney, B. Hill, S. Hopkins, 

 K. Kritz, from the U.S. Bureau of Land Management, and D. 

 Gutherie and S. Livingston of the U.S. Forest Service. 



F. Ramsey and D. Schafer from Oregon State University, 

 Statistics Department provided assistance with data analyses. 

 We thank J. Baldwin, B. Block, A. Burger, P. Connors, T. 

 De Santo, R. Mannan, C.J. Ralph, M. Raphael, R. Steidl and 

 J. Weeks for reviewing earlier drafts of this manuscript and 

 making numerous suggestions that greatly improved its 

 quality. Support for preparation of this manuscript was 

 provided by the Oregon Department of Fish and Wildlife, 

 USDA Forest Service, USDI Bureau of Land Management, 

 and U.S. Fish and Wildlife Service, U.S. Department of 

 Interior. This is Oregon State University Agricultural 

 Experiment Station Technical Paper Number 10,537. 



USDA Forest Service Gen. Tech. Rep. PSW-152. 1995. 



201 



