Burger 



Chapter 16 



Inland Habitat Associations in British Columbia 



Stand Attributes and Relative 

 Murrelet Densities 



Elevation 



Eisenhawer and Reimchen (1990) found no evidence of 

 Marbled Murrelets in high elevation (to 700 m) subalpine 

 scrub forest of lodgepole pine above Coates Lake, Queen 

 Charlotte Islands. At Lagins Creek, Queen Charlotte Islands, 

 Rodway and others (1991, 1993a) found a significant 

 difference in mean detection rates in May through July 

 between low elevation forests (90-150 m), high forests (230- 

 460 m), and alpine areas (720-1000 m): 32.4 4.1 (s.e.), 

 17.5 3.0, and 3.0 0.7 detections per survey, respectively. 

 About 98 percent of the old-growth forest occurred below 

 500 m in this area. A few birds passed over alpine ridges in 

 this area, but 84 percent of the detections in high altitude 

 stations were of birds 500-1500 m distant, flying in the 

 valleys below. Ground searches in alpine areas yielded no 

 sign of nesting. 



Marbled Murrelets do nest in some high altitude forests 

 above fjords on the mainland coast. Murrelets have been 

 reported flying over the steep slopes, mostly covered in 

 scrubby sub-alpine forest with patches of taller trees, which 

 surround fjords (Burns, pers. corrun.; Kaiser, pers. comm.; 

 Prestash, pers. comm.). One radio-tagged bird was tracked 

 to a sub-alpine stand of large conifers above Mussel Inlet 

 (Prestash and others 1992b; see details below). Similar habitat 

 appears to support Marbled Murrelets in the Kitlope drainage 

 on the north-central mainland (Kelson, pers. comm.). 



Fairly high rates of activity (details below) were reported 

 from sub-alpine forest at 750-1200 m, dominated by 

 mountain hemlock and yellow cedar in the Caren Range, 

 Sechelt Peninsula (Jones 1992; P. Jones, pers. comm.). An 

 active nest was found here in 1993 at 1088 m (Jones 1993). 

 A fledgling Marbled Murrelet was found alive on the ground 

 by a tree faller at Downing Creek, near Furry Creek on the 

 east side of Howe Sound in 1985. The suspected nest was at 

 the top of a "red cedar" (sic) at an altitude of 1064 m 

 (Morgan 1993). 



Marbled Murrelets nest as high as 1000 m, and these 

 somewhat meager data suggest that vegetation development, 

 specifically the absence of large trees at high altitudes, affects 

 Marbled Murrelets more than altitude per se. 



Aspect, Slope and Stand Position on Slope 



The effects of slope and aspect have not been adequately 

 investigated in British Columbia. High elevation stations on 

 side slopes in two watersheds in the Queen Charlotte Islands 

 (see above for altitudes) had lower detection rates than those 

 in the valley bottoms, but this might be a consequence of 

 elevation, rather than slope or aspect (Rodway and others 

 1991, 1993a). These authors pointed out that if birds circled 

 over narrow valleys, they would probably pass over observers 

 on the valley floor more often than observers on the side 

 slopes, causing differences in detection frequencies. 



Vegetation Classification and Tree Size 



Intensive surveys in Lagins Creek, Queen Charlotte Island, 

 by Rodway and others (1993a) yielded the highest densities 

 of detections in stands of large Sitka spruce and western 

 hemlock. These preferred stands included the following site 

 associations: (1) valley bottom, western red cedar/Sitka spruce 



- foamflower (mean diameter at breast height [d.b.h.] = 162 

 cm); (2) valley bottom, western red cedar/Sitka spruce - 

 Conocephalum (d.b.h. = 104 cm); and (3) slope forest, western 

 hemlock/Sitka spruce - lanky moss (d.b.h. = 93 cm). Within 

 these associations, vegetation groups with the largest trees 

 (mean d.b.h. 141 cm vs. 60 cm for all other plots) had 

 significantly higher rates of murrelet detections. These 

 differences disappeared when only low-altitude sites were 

 considered. Lower detections rates were found in these site 

 associations: (1) valley bottom, western red cedar/Sitka spruce 



- skunk cabbage (d.b.h. = 40.4 cm); (2) higher altitude, 

 western red cedar/western hemlock - blueberry (d.b.h. not 

 measured); and (3) lodgepole pine/yellow cedar - sphagnum 

 (d.b.h. not measured) found in low-elevation bog-forest. 



Reimchen (1991) made informal observations of flight 

 activity of Marbled Murrelets (not following the Pacific 

 Seabird Group protocol) at 49 lakes on Graham and Moresby 

 Islands (Queen Charlotte Islands) between 25 May through 

 25 July over a 12 year period. The birds were absent or rare 

 (<2 calls per 15 minute survey) at 40 lakes, most of which 

 were surrounded by unforested scrubby vegetation or "poorly 

 forested" terrain. The nine lakes at which there was extensive 

 murrelet activity were distributed primarily in old-growth 

 forest with mossy boughs. Sitka spruce appeared to be an 

 important component of the vegetation at active sites. Intensive 

 observations by Eisenhawer and Reimchen (1990) at Coates 

 Lake, Graham Island from 1 June to 3 August 1986 yielded a 

 mean of 12.9 (range 1-50, n = 42) detections per dawn 

 survey, as well as records of birds carrying fish, landing on 

 trees, and possibly copulating on a branch. The old-growth 

 forests here were mixtures of western hemlock, Sitka spruce, 

 western red cedar, and yellow cedar, with canopies 40-70 m 

 tall. No detailed habitat plots were made. 



Murrelet activity was reported over the steep forested 

 slopes overlooking Mussel Inlet, a northern mainland fjord 

 (Prestash and others 1992b; Prestash, pers. comm.; Burns, 

 pers. comm.). The forests were primarily within the Very 

 Moist Coastal Western Hemlock (CWHvml and CWHvm2) 

 and Moist Maritime mountain hemlock (MHmml) biogeo- 

 climatic subzones. Two radio-tagged murrelets were 

 repeatedly tracked to forest stands here (the third radio- 

 tagged bird reported by Prestash and others [1992b] appeared 

 to have lost its transmitter or died in the forest). Vegetation 

 characteristics of these stands were derived from forest 

 inventory maps. One stand was in sub-alpine hemlock/amabilis 

 fir forest (400 m asl) with large mountain hemlock trees (37- 

 46 m tall, estimated age >250 years), and the second in a low 

 altitude (80 m) moss-covered bog-forest dominated by western 

 red cedar (28-37 m, estimated 141-250 years old). 



156 



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



