Ralph and others 



Chapter 1 



Overview of Ecology and Conservation 



the breeding season (April-August), but move elsewhere 

 when not breeding, presumably in response to food 

 availability, which becomes more problematic during winter. 

 Murrelets do, however, have the ability to fly long distances 

 to reach suitable foraging habitat or areas with high 

 productivity, even during the breeding season. 



In northern Washington, British Columbia, and Alaska, 

 the small-scale relationship between the at-sea distribution 

 of murrelets and the presence of old-growth immediately 

 adjacent to the coast is less clear. In this part of the murrelet's 

 range, the coastline is much more complex. The numerous 

 islands, bays, fjords, and sheltered inside waters, the greater 

 abundance of contiguous stands of mature, old-growth 

 forests, and the lack of survey effort, all have hindered 

 assessment of fine-scale spatial associations between nesting 

 and foraging habitat. 



Inland, murrelets are detected almost exclusively in forest 

 stands with old-growth characteristics (Burger, this volume 

 a; Grenier and Nelson, this volume; Hamer, this volume; 

 Kuletz and others, this volume; Paton and Ralph 1990; Rodway 

 and others 1993b). All murrelet nests, south of Alaska, have 

 been found in old-growth trees (>81 cm d.b.h.), therefore all 

 nests have been in stands with old-growth trees. To our 

 knowledge, essentially all stands with birds flying below the 

 canopy (termed "occupied behaviors") have also been in 

 stands with old-growth trees. Grenier and Nelson (this volume) 

 found all occupied sites had at least one old-growth tree per 

 acre. There are reports of possibly occupied inland sites in 

 Oregon without old-growth trees, but Nelson (pers. comm.) 

 had not verified occupancy in most of these areas. By contrast, 

 there is a high probability that a few murrelets are nesting in 

 coastal stands without old-growth trees in the Sitka spruce/ 

 western hemlock (Picea sitchensis/Tsuga heterophylld) forest 

 type in Oregon (Nelson, pers. comm.). This forest type may 

 provide nesting habitat at younger ages because trees grow 

 fast in this area and smaller trees may also be used because 

 mistletoe deformations are abundant in the hemlock trees. 

 Young Douglas-fir (Pseudotsuga menziesii) forests do not 

 provide the same opportunities. 



Ground nesting by Marbled Murrelets has been 

 documented in Alaska. Available information suggests that 

 less than 5 percent of the total murrelet population in 

 Alaska breeds on the ground in non-forested habitat in the 

 western Gulf of Alaska and in the Aleutian Islands 

 (Mendenhall 1992). There is also a small unknown 

 percentage of the population that nests on the ground in 

 old-growth forests; about five nests have been found to 

 date (Kuletz, pers. comm.). It is important to recognize that 

 despite these markedly different breeding habits, intermediate 

 situations are generally not acceptable to murrelets. To our 

 knowledge they do not breed in alpine forests, bog forests, 

 scrub vegetation, scree slopes, and very rarely breed in 

 second growth (e.g., trees <81 cm d.b.h.) (Rodway and 

 others 1993b). In the farthest northern portion of the range 

 in Alaska (Kuletz and others, in press; Naslund and others, 

 in press), and in the habitat of the Asian taxon of the 



murrelet (Konyukhov and Kitaysky, this volume), the nest 

 trees become relatively short in stature, as compared to 

 trees in forests farther south in North America. In these 

 areas, murrelets appear to nest in the largest trees of the 

 oldest forests. On the basis of all the information available, 

 we conclude that throughout their range in North America, 

 the great majority of murrelets are strongly associated with 

 old-growth forests for breeding. 



Distribution in Relation to Distance from the Coast 



The maximum distance that murrelets can occur inland 

 from coastal foraging areas may result from several factors, 

 including suitability of climate, availability of nesting habitat, 

 the maximum foraging range, and rates of predation. Average 

 and maximum summer temperatures increase as a function 

 of distance from the coast and the decreased influence of 

 cool maritime breezes. For a well-insulated, oceanic species 

 spending more than 95 percent of its time on the cold waters 

 of the Pacific, inland temperatures in the south of its range 

 could be too hot for nesting. Greater distances to the coast 

 would also require longer foraging flights. For other species 

 of alcids, typical one-way foraging ranges are 10-40 km, 

 with maximum extremes of 100-150 km (Ainley and others 

 1990; Bradstreet and Brown 1985). For murrelets, studies of 

 foraging range using radio-tagged birds have indicated that 

 this species will fly up to 75 km from its nesting areas to 

 forage, with most trips being considerably shorter (Burns 

 and others 1994, Rodway and others, in press). The maximum 

 distance inland at which murrelets have been found is about 

 100 km although most appear to nest less than 60 km inland 

 (Hamer, this volume; Miller and Ralph, this volume). Records 

 for maximum inland distance based on the discovery of 

 grounded fledglings may be misleading because of the 

 possibility of misdirected birds flying inland from their nest. 

 Average distances of inland nesting cannot be firmly 

 ascertained until the distribution of inland detections of 

 murrelets is documented with a consistent survey effort. We 

 do not know how the potential for nest site predation may 

 vary with distance from the coast, but certainly longer flights 

 between the nest sites and at-sea foraging areas increase the 

 chance of being taken by aerial predators. 



Although in some regions murrelets nest immediately 

 adjacent to the coast, in most portions of their range studied 

 the majority of nests are inland from the immediate coast. In 

 Alaska, murrelets nest within 1 km of salt water (Kuletz and 

 others, this volume; Naslund and others, in press), and in 

 California the highest proportions of nesting stands are found 

 within 10 km of the coast (Miller and Ralph, this volume). 

 At least in the southern part of the range, we suspect that the 

 readily-harvested trees on the coast were the first to be 

 removed, leaving the more distant ones for future cutting 

 and thereby influencing current patterns of murrelet nesting. 



Comparison of Habitat Correlates 



Several studies and surveys have documented behaviors 

 at inland stands that are probably indicative of nesting (Nelson 



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



