Nelson and Hamer 



Chapters 



Nest Success and Effects of Predation 



combination of low annual nesting success, low fecundity 

 rates (Beissinger, this volume), and low or declining 

 population sizes (Carter and Erickson 1992; Kelson and 

 others, in press; Kuletz, 1994), could impact the survival and 

 recovery of this threatened seabird. 



Conclusions 



Results from this study suggest that predation on murrelet 

 nests may be relatively high compared with many alcids and 

 forest nesting birds. Because Marbled Murrelets have no 

 protection at nest sites other than the ability to remain hidden 

 (Nelson and Hamer, this volume a), the availability of safe 

 nest sites will be imperative to their survival. If logging and 

 development (e.g., clearing land, creating patches of habitat, 

 thinning stands) within the murrelet' s range has resulted in 

 increased numbers of predators or predation rates, and has 

 made murrelet nests easier to locate because of increased 

 amounts of edge and limited numbers of platforms with 

 adequate hiding cover, then predation on murrelet nests 

 could be significantly higher in such situations. In addition, 

 areas heavily used by humans fci recreational activities (i.e., 

 picnic and camping grounds) ca-i attract corvids (Marzluff 

 and Balda 1992, Singer and others 1991) and may increase 

 the chance of nest predation within these areas. Therefore, 

 we hypothesize that because this seabird has low reproductive 

 rates (one egg clutch), small increases in predation will have 

 deleterious effects on murrelet population viability. 



Rigorous studies should be developed to investigate the 

 effects of predator numbers, predator species, predator 

 foraging success, landscape patterns, habitat types, and forest 

 structural characteristics on Marbled Murrelet nesting success. 

 In implementation of these studies, hypotheses on the effects 

 of various habitat features on fitness components (recruitment 

 and demography) should be tested (Martin 1992, Paton 1994). 

 At the same time, the effects of these hypotheses on coexisting 

 species and the interacting effects these species have on one 

 another should be evaluated (Martin 1992). 



Acknowledgments 



We are grateful to the biologists who kindly shared their 

 data with us; special thanks go to Jim Atkinson, Alan Burger, 

 Stephanie Hughes, John Hunter, Paul Jones, Kevin Jordan, 

 John Kelson, Steve Kerns, Kathy Kuletz, Irene Manley, Ray 

 Miller, Nancy Naslund, Bill Ritchie, Steve and Stephanie 

 Singer, and David Suddjian for their time and generosity. 

 We also thank Alan Burger, George Hunt, John Marzluff, 

 Robert Peck, Steve Speich, and several anonymous reviewers 

 for providing valuable comments on earlier drafts of this 

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

 the Interior. This is Oregon State University Agricultural 

 Experiment Station Technical Paper 10,540. 



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



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