Ralph and Miller 



Chapter 33 



Offshore Population Estimates in California \ 



were repeated over several years, under usually optimal 

 conditions. Thus, we are confident that our population estimates 

 are more accurate than those derived from past, preliminary 

 survey work. 



Comparison of Coastal and Inland Habitat Distribution 



Murrelets are found at sea in California offshore of old- 

 growth redwood forests. The only minor exception is the 

 population in the vicinity of Trinidad. This population is 

 about 30 km to the south and west of the major concentration 

 of old-growth in Redwood National Park. The waters in this 

 area are felt to be unusually productive by knowledgeable 

 fisheries biologists (Roelofs, pers. comm.), perhaps explaining 

 the abundance of murrelets in the area. A 20- to 30-km flight 

 from nesting to foraging areas is well within the capabilities 

 of murrelets. In British Columbia murrelets with radio 

 transmitters were regularly tracked 40 to 60 km on daily 

 flights from feeding areas to presumed inland nesting sites 

 (Varoujean, pers. comm.). 



The coincidence of the fragmentation of the offshore 

 population and the fragmentation of the remaining large 

 stands of old-growth forests adds weight to the argument that 

 the species is dependent for nesting habitat on these stands. 



Risk Factors 



Our documentation of two population centers in the 

 state with a decline of numbers from north to south, make it 

 important to ensure that offshore populations are protected 

 from mortality from oil spills and gill nets. Both these risks 

 are present today, and the concentration of birds in local 

 areas, especially the southern population, make them 

 especially vulnerable to extirpation. 



Recommendations 



The data on the offshore populations of the murrelet we 

 have gathered over the past five years can provide a basis for 

 determining future population changes. We suggest that these 

 surveys continue annually to monitor this threatened species, 

 as well as the other species frequenting the nearshore waters. 

 Any monitoring program should also include collection 

 data on the production of young by determining the presence 

 of newly-fledged birds while they are distinguishable fron 

 winter-plumaged adults. With such a plan and a regula 

 monitoring program in place, we can determine the healt 

 and trend of the population of this unique species. 



Acknowledgments 



We thank California Department of Fish and Game 

 California Department of Forestry, California Department 

 of Transportation, U.S. Minerals Management Service 

 Redwood National Park, the USDA Forest Service, and tli 

 timber industry's Marbled Murrelet Trust that includes The 

 Pacific Lumber Company, Arcata Redwood Company, Miller- 

 Rellim Company, Barnum Timber, and Eel River Sawmill 

 for financial support. We are grateful to our many brave 

 hearty, and capable observers for their many hours on the 

 ocean, especially: Brian O'Donnell, Linda Long, Kir 

 Hollinger, Brian Cannon, Dave Forty, Jennifer Weeks, David 

 Craig and Greg Heidinger. We thank Ann Buell, Esther 

 Burkett, George Hunt, Deborah Kristan, Linda Long, Nadav 

 Nur, John Piatt, Larry Spears, Steven Speich, Bill Sydeman, 

 and Jennifer Weeks for their comprehensive and helpful 

 manuscript reviews, and James Baldwin and Kevin McKelvey 

 for their statistical advice. We appreciate the efforts of the 

 many field personnel who gathered data for the study. 



360 



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



