Ralph and others 



Chapter 1 



Overview of Ecology and Conservation 



km of the coast. In forests, most nest sites are on large 

 diameter, often moss-covered, limbs. The small, relict 

 populations at the limits of the range are particularly vulnerable 

 to extirpation, and will require careful stewardship if they 

 are to be preserved. At sea, foraging murrelets are usually 

 found as widely spaced pairs. In some instances, murrelets 

 join into flocks that are often associated with river plumes 

 and currents. These flocks may contain sizable portions of 

 local populations. Protection of foraging habitat and foraging 

 murrelets will be necessary if adult mortality is to be minimized. 



Marbled Murrelets are secretive on land, but spend most 

 of their lives at sea, where they are relatively easily observed. 

 Data obtained at sea are at present the best source of 

 information about the distribution and abundance of the 

 species. Patterns of distribution provide information on the 

 murrelet's geographic range, terrestrial nesting habitats, and 

 the oceanographic features of foraging areas. 



Nest sites of the species were found only relatively 

 recently. We can find no historical account that gives any 

 credibility to the notion that the murrelet could nest in trees, 

 although Dawson (1923) mentions (and then debunks) an 

 apocryphal Indian account of them nesting inland in "hollow 

 trees." Today, this seems easily interpretable as large, old 

 trees containing hollows. In 1923, Joseph Grinnell (quoted 

 in Carter and Erickson 1988) noted indirect evidence that the 

 bird was associated with older forests. Since then, observers 

 have noted links of the species with what has come to be 

 called "old-growth" forests, that we define here for 

 convenience as forests that have been largely unmodified by 

 timber harvesting, and whose larger trees average over 200 

 years old. This definition of old-growth is in general agreement 

 with the ideas of Franklin and others (1986). In some places 

 in this chapter we refer to old-growth trees as those with a 

 diameter of more than 8 1 cm. 



In the following chapters, various authors discuss how a 

 shift from efforts to find nest sites to broader surveys 

 monitoring the presence of murrelets in forested tracts, 

 especially those slated for timber harvest, have increased the 

 knowledge of the use of inland sites by murrelets. These 

 efforts have resulted in a more complete picture on current 

 distribution and abundance which may lead the way for 

 management for this species. 



Marine surveys remain the only method for estimating 

 the size of Marbled Murrelet populations. These surveys have 

 been carried out in a variety of intensities, and the most recent 

 data are presented in the chapters to follow. Unfortunately, 

 relatively little historical survey information is available. Early 

 surveys were focused on species found in deeper waters, 

 while the nearshore murrelet was generally ignored. Further, 

 recent work has shown that to obtain useful data on murrelet 

 distribution and abundance, surveys must be designed to 

 focus on the nearshore waters where murrelets are found. 



Taxonomy and Range 



The species has been divided into two races, the North 

 American (Brachyramphus marmoratus marmoratus) and 



the Asian (B. m. perdix). Recent evidence, not yet fully 

 published in the literature (Friesen and others 1994a), strongly 

 indicates that the North American race may be more distinct 

 from the Asian race (referred to as the Long-billed Murrelet, 

 B. perdix) than it is from the other North American 

 Brachyramphus, the Kittlitz's Murrelet (B. brevirostris). 

 Konyukhov and Kitaysky (this volume) contrast the Asian 

 and North American races. 



From California to Alaska, the Marbled Murrelet nests 

 primarily in old-growth coniferous forests and may fly up to 

 70 km or more inland to nest. This is a radical departure 

 from the breeding behavior of other alcids, but adaptation to 

 old-growth conifers probably occurred early in its evolutionary 

 history, perhaps in the mid-Miocene when enormous dawn 

 redwoods (Metasequoia) blanketed the coast from California 

 to the north slope of Alaska and Aleutian Islands. The other 

 21 extant species of the family Alcidae, known as auks or 

 alcids, breed on the ground, mostly on predator-free islands. 

 In Alaska, a very small proportion of the Marbled Murrelets 

 breed on the ground, usually on barren, inland slopes and to 

 the west of the major rain forests along the Alaskan gulf 

 coast. Initial divergence of perdix and marmoratus occurred 

 in the mid-Pliocene, perhaps as cooling temperatures 

 eliminated coastal old-growth forests in the exposed Aleutian 

 Islands, leading to a gap in east- west distribution of murrelets 

 and isolated breeding stocks (Udvardy 1963). The divergence 

 of Marbled and Kittlitz's murrelets occurred at the onset of 

 the Pleistocene (Friesen and others 1994), and the present 

 strong association of Kittlitz's Murrelet with glacial ice 

 clearly indicates the importance of the glacial landscape in 

 determining the northeasterly distribution of Kittlitz's Murrelet 

 and ecological segregation of brevirostris and marmoratus 

 into subarctic and boreal species. 



Geographic Range 



At the broad scale, the distribution of the Marbled 

 Murrelet is fairly continuous from the Aleutian Islands to 

 California. The present geographic center of the North 

 American populations is found in the northern part of southeast 

 Alaska (fig. 1). Large populations are also found to the west 

 around Prince William Sound and the Kodiak Island 

 archipelago, and to the south along the British Columbia 

 coast. In either direction, populations become more disjunct, 

 with small, discrete sub-populations at the extreme ends of 

 the range in the Santa Cruz Mountains of central California, 

 and on Attu Island in the western Aleutians. In California, 

 Oregon, and Washington, gaps in distribution between 

 breeding populations may result largely from timber harvest 

 practices. The disjunct distribution is a reflection of the 

 remaining nesting habitat, primarily late-successional and 

 old-growth forests on public land (Carter and Erickson 1992, 

 Leschner and Cummins 1992a, Nelson and others 1992). 



The small, relict populations of murrelets at the limits of 

 the species' range are particularly vulnerable to extirpation. 

 Particular care will need to be exercised if they are to be 

 conserved. Murrelets range along 4,000 km of coastline and it 

 is possible that some populations have distinct genetic 



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



