Ralph and others 



Chapter 1 



Overview of Ecology and Conservation 



not been documented at sea. Given the small number of nest 

 sites that have been monitored, observations of the taking of 

 adult murrelets by predators raises the possibility that this is 

 not a rare event. In recently documented cases, a Sharp-shinned 

 Hawk (Accipiter striatus) in Alaska attacked and killed a 

 murrelet as it came to its nest (Marks and Naslund 1994), 

 and a Peregrine Falcon was observed taking adults at Waddell 

 Creek, California (Suddjian, pers. comm.). In Alaska, Marbled 

 Murrelet wings were the most common prey remains found 

 at coastal Peregrine Falcon nests (Jeff Hughes, pers. comm. 

 to Kuletz), bones have been found at other Peregrine aeries 

 (Campbell and others 1977), and the remains of unidentified 

 alcids have also been found in goshawk nests (Iverson, pers. 

 comm.). These anecdotal reports are primarily within the 

 Gulf of Alaska region, where Ancient Murrelets were also 

 found to form an important part of the Peregrine's diet 

 (Gaston 1992). Therefore, it seems likely that Marbled 

 Murrelets may also form a substantial part of the diet of 

 avian predators. 



Marbled Murrelets are vulnerable to discharge of pollution 

 from point sources on land, to fouling by spilled oil, and to 

 bycatch in gill nets (Carter and Kuletz, this volume; Carter 

 and others, this volume; Fry, this volume; Kuletz 1994; Piatt 

 and Naslund, this volume). Pollution discharged from point 

 sources on land, particularly when it enters partially enclosed 

 shallow bays, is a potential problem (Fry, this volume). For 

 example, Miller and Ralph (unpubl. data) observed an increase 

 in murrelet use of the coast immediately north of Humboldt 

 Bay in 1993 after pulp mill effluent ceased to be discharged 

 into the ocean. This was likely a response to increased prey 

 (Ainley, pers. comm.). Oil spills are also of considerable 

 concern, and have caused numerous losses of murrelets. In 

 Alaska, the Exxon Valdez oil spill is estimated to have killed 

 about 8,400 murrelets, approximately 3.4 percent of the 

 Alaska population (Piatt and Naslund, this volume). 



Nearshore gill-net fisheries are an important source of 

 annual mortality in some regions. Murrelets are particularly 

 vulnerable to entanglement in gill nets during the hours of 

 darkness (Carter and others, this volume). Based on the 

 compilation of DeGange and others (1993), an estimated 

 2,000 to 3,000 Marbled Murrelets are killed annually in 

 Alaskan gill-net fisheries. In Barkley Sound, British Columbia, 

 Carter and Sealy (1984) estimated that a gill-net fishery for 

 salmon (Salmo sp.) in 1980 killed 7.8 percent of the projected 

 fall population of murrelets. The location of that fishery was 

 in an area where high densities of murrelets overlapped with 

 an area that was intensively fished. That fishery has not 

 opened in every year since 1980 (Carter, pers. comm. in 

 DeGange and others 1993), and the 1980 value might not be 

 typical of a long-term average mortality. In Puget Sound, 

 Washington, Wilson (pers. comm.), estimated that as many 

 as several hundred murrelets are killed in gill nets annually. 

 These numbers, if correct, are a large proportion of the 

 estimated murrelet population in the Sound. Few, if any, 

 murrelets are killed in gill nets in Oregon or California, 

 although, prior to the ban of shallow water gill netting in 



California, murrelets were killed (DeGange and others 1993). 

 The annual mortality rates of Marbled Murrelets projected 

 for salmon gill-net fisheries of Washington, British Columbia, 

 and Alaska are of a magnitude to cause concern because of 

 overriding influence of adult survivorship on murrelet 

 demographics (Beissinger, this volume). 



The Future Course of Habitat and 

 Populations 



Habitat Trends 



We believe that the ultimate fate of the Marbled Murrelet 

 is largely tied to the fate of its reproductive habitat, primarily 

 old-growth forest or forest with an older tree component. It 

 is clear that the amount of Marbled Murrelet nesting habitat 

 has declined over the past 50 years, due primarily to timber 

 cutting (Perry, this volume). Bolsinger and Waddell (1993) 

 estimated that total acres of old-growth forest in California, 

 Oregon, and Washington declined from nearly 33 million 

 acres in the 1930s to about 10 million acres in 1992 (of a 

 total forested area of 66 million acres), although their analysis 

 was based on a broader region than the range of the Marbled 

 Murrelet. Of the remaining 10 million acres of old-growth in 

 this region, 85 percent is under federal ownership. Federal 

 lands within the range of the northern race of the Spotted 

 Owl (Strix occidentalis) in these three States contain an 

 estimated 2.55 million acres of potential murrelet nesting 

 habitat (U.S. Dep. Agric./U.S. Dep. Interior 1994). Some 

 biologists, however, estimate that much of this land is too far 

 inland and at too high an elevation to be used by murrelets 

 (Hamer, pers. comm.). Assuming these federal lands represent 

 about 85 percent of all murrelet nesting habitat on all lands, 

 the future of current habitat heavily depends on management 

 decisions on the federal lands. 



The U.S. Government's Forest Plan is projected to 

 conserve 89 percent of current murrelet nesting habitat within 

 various categories of reserves on Federal lands in California, 

 Oregon, and Washington. This amount of land represents 

 approximately 75 percent of present murrelet nesting habitat 

 in the three States. In addition, the plan calls for protection 

 of nesting habitat within half-mile circles around all occupied 

 sites. Therefore, in the short term, we expect little further 

 loss of current habitat on Federal lands if the plan is 

 implemented (although some occupied sites have been 

 released to logging). Over the long term, we expect the 

 amount of habitat on Federal lands to increase, as younger 

 forest within these reserves matures. 



In Alaska, about 90 percent of the coastal old-growth 

 forests remain from Kodiak Island to northern Southeast 

 Alaska. Approximately 93 percent of what is classified as 

 productive (and of that, about 58 percent of the highly 

 productive component) old-growth forests that represent 

 Marbled Murrelet habitat remain on the Tongass National 

 Forest in southeast Alaska (Perry, this volume). At this time 

 there is no direct evidence that highly productive stands are 



16 



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



