Chapter 6 



Characteristics of Marbled Murrelet Nest Trees 

 and Nesting Stands 



Thomas E. Hamer 1 



S. Kim Nelson 2 



Abstract: We summarize the characteristics of 61 tree nests and 

 nesting stands of the Marbled Murrelet (Brachyramphus 

 marmoratus) located from 1974 to 1993 in Alaska, British Colum- 

 bia, Washington, Oregon, and California. Evidence of breeding 

 30-60 km inland was common in California, Oregon, and Wash- 

 ington. Nesting greater distances from the coast may have evolved 

 to avoid nest predation by corvids and gulls which are more 

 abundant in coastal areas. In California, Oregon, Washington, and 

 British Columbia, murrelets nested in low elevation old-growth 

 and mature coniferous forests, with multi-layered canopies (>2), a 

 high composition of low elevation conifer trees ( x = 91 percent) 

 and, on the lower two-thirds of forested slopes, with moderate 

 gradients (x =23 percent slope). Stand canopy closure was often 

 low ( x = 50 percent), suggesting use of canopy openings for 

 access to nest platforms. Nests in the Pacific Northwest were 

 typically in the largest diameter old-growth trees available in a 

 stand ( x =211 cm); many nest trees were in declining conditions 

 and had multiple defects. It is likely that western hemlock and Sitka 

 spruce constitute the most important nest trees, with Douglas-fir 

 important south of British Columbia. Many processes contributed 

 to creating the nest platforms observed. Mistletoe blooms, unusual 

 limb deformations, decadence, and tree damage, commonly ob- 

 served in old-growth and mature stands, all appear to create nest 

 platforms. Therefore, the stand structure and the processes within a 

 stand may be more important than tree size alone in producing 

 nesting platforms and suitable habitat. Moss cover was also an 

 important indicator of suitable nesting habitat. 



We summarize the characteristics of 6 1 tree nests and 

 nesting stands of the Marbled Murrelet (Brachyramphus 

 marmoratus) located from 1974 to 1993 in Alaska, British 

 Columbia, Washington, Oregon, and California (table 1). 

 The majority of the nest site information was unpublished 

 and obtained directly from field biologists who were 

 conducting inland studies on the murrelet. The preponderance 

 of unpublished nest information is due to the recent discovery 

 of most nest sites. The only other summary was completed 

 by Day and others (1983), based on two tree nests and five 

 ground nests of the Marbled Murrelet. 



Because of the murrelet' s small body size, dense forested 

 nesting habitat, cryptic plumage, crepuscular activity, fast 

 flight speed, and secretive behavior near nests, its nests 

 have been extremely difficult to locate. The first tree nest 



1 Research Biologist, Hairier Environmental, 2001 Highway 9, Mt. 

 Yemen, WA 98273 



2 Research Wildlife Biologist, Oregon Cooperative Wildlife Research 

 Unit, Oregon State University, Nash 104, Corvallis, OR 97331-3803 



was located only in 1974 (Binford and others 1975), despite 

 decades of searching by ornithologists in North America. 

 Although a significant amount of nesting habitat information 

 has been collected over the past four years, the efficiency 

 of locating active nests is still low. Experiences gained 

 from nest search efforts have led to the development and 

 refinement of methodologies for locating new nests (Naslund 

 and Hamer 1994). 



Fortunately, an increased understanding of murrelet 

 nesting ecology has allowed biologists to locate nests that 

 have not been used for several months or, in some cases, 

 several years. This involves searching for old nest cup 

 depressions, worn spots or "landing pads" created on moss- 

 covered branches by visiting adults, old fecal rings, and 

 habitat features commonly associated with suitable nesting 

 platforms. In addition, biologists learned that eggshells could 

 be located in the duff and litter of nest platforms unused for 

 a year or more. 



Intensive search efforts by biologists across the Pacific 

 Northwest have led to the discovery of 65 tree nests since 

 1974, with 63 (95 percent) located since 1990. Although this 

 is still a relatively small sample size considering the large 

 geographic area these nests represent, the sample does allow 

 a characterization of the tree nests and nesting stands. 



The two species of murrelets in the genus Brachyramphus 

 (Kittlitz's and Marbled) display a complete dichotomy in 

 their choice of nesting habitat. The Kittlitz's (B. brevirostris) 

 murrelet nests up to 30 km inland on the ground on exposed 

 rocky scree slopes, often at higher elevations. The Marbled 

 Murrelet is unique among Alcids in selecting almost 

 exclusively to nest on large limbs of dominant trees, which 

 can be located long distances from the marine environment. 



Long considered a subspecies of the Marbled Murrelet, 

 the Asian race of the Marbled Murrelet (B.m. perdix Pallas) 

 is distributed from the Kamchatka Peninsula south to Japan. 

 New genetic evidence (Friesen and others 1994a) indicates 

 the it is most likely a distinct species from the Marbled 

 Murrelet. From the little evidence collected to date, it may 

 be an obligate tree nesting seabird (Konyukhov and 

 Kitaysky, this volume), with its range coinciding closely 

 with the coastal coniferous forests of Russia and Japan 

 (Kuzyakin 1963). 



At a few sites in Alaska and Russia, at or beyond the 

 margin of Pacific Coastal coniferous forests, the Marbled 

 Murrelet nests on the ground. From an examination of the 

 summer distribution of the species, approximately 3 percent 

 of the Alaskan murrelet population may nest on the ground 

 (Piatt and Ford 1993). These nests have been found at 



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



69 



