Kuletz and others 



Chapter 15 



Inland Habitat Suitability in Southcentral Alaska 



exposed coasts near fjord mouths bordering the Gulf of 

 Alaska (Bailey 1976). Glaciers cover more than 50 percent 

 of Kenai Fjords National Park (Selkregg 1974). Because of 

 receding glaciers, forested portions of the coast are primarily 

 in the outer, more exposed headlands and islands. Tree line 

 is typically 300 m, and few areas beyond 500 m from shore 

 are forested. Tree species are similar to those in Prince 

 William Sound, and alder is the dominant vegetation in 

 unforested areas. 



There were two study sites on Afognak Island. The 

 northern parcel faces north into the Gulf of Alaska and is 

 heavily forested. The southwest parcel faces west into Shelikof 

 Strait and is primarily unforested, except along river valleys 

 and around the heads of bays. There are no glaciers. Tree 

 line ranges from 1 00 to 300 m and the only conifer is Sitka 

 spruce (Picea sitchensis), which tends to be larger than on 

 the mainland. 



Data Collection 



Dawn Watch Surveys 



In Alaska, surveys are limited by logistic considerations 

 due to inaccessibility of coastal habitats, and by the relatively 

 short time available for breeding surveys (mid-May through 

 early August). Therefore, intensive surveys (hereafter referred 

 to as "dawn watches"; Paton and others 1990, Ralph and 

 others 1993) were conducted from land-based ("upland") 

 sites and from boats anchored near shore. The basic unit of 

 measure was the 'detection' which is defined as "the sighting 

 or hearing of a single biid or a flock of birds acting in a 

 similar manner" (Paton and others 1990). We assume that 

 dawn activity (i.e., numbers of detections) is positively related 

 to nesting activity. We recognize, however, that no quantitative 

 relationship between dawn activity and numbers of nesting 

 murrelets has been defined, and conclusions about relative 

 use of different habitats are tentative. 



Dawn watches were modified for southcentral Alaska 

 (for more details see Kuletz 1991b, Kuletz and others 1994c). 

 Modifications included: (1) earlier start and finish times 

 relative to sunrise (i.e., usually beginning 105 min before 

 official sunrise and lasting until 15 min after sunrise, or 15 

 min after the last murrelet detection) to compensate for 

 greater light levels in Alaska; (2) addition of behavior 

 categories not observed further south; and (3) some watches 

 were conducted from boats and shore to allow sampling of 

 shoreline habitat. Using landmarks, we designated each 

 detection as <200 m or >200 m from the observer. When the 

 dawn watch was conducted near the water, a bird passing 

 over land at any time during the observation was designated 

 a land detection. 



Behaviors indicative of murrelet nesting are referred to 

 as "occupied behaviors." These included flying below canopy, 

 emerging from or flying into trees, landing on or departing 

 from a branch, or calling from a stationary point in the forest 

 (Paton and others 1990). In unforested areas we considered 

 flights into hillsides or brush or <3 m above ground cover to 

 be occupied behaviors. Occupied sites were those with at 



least one recorded occupied behavior. We considered other 

 sites to be of "unknown status" since a single visit was not 

 sufficient to determine whether a site was unoccupied (Ralph 

 and others 1993). 



Habitat Variables 



A 50-m vegetation plot was sampled at each dawn watch 

 site. When the dawn watch was conducted from shoreline or 

 from a boat, the vegetation plot center was placed within the 

 habitat most visually representative of the area adjacent to 

 the dawn watch site. Within the plot we measured the diameter 

 at breast height (d.b.h.) of the 10 nearest upper canopy trees, 

 the percentage of epiphyte cover on the branches of each 

 tree, and the number of platforms per tree (horizontal surfaces 

 >15 cm diameter and >10 m above the ground). Data on 

 epiphyte cover and platforms were not collected for the 

 Naked Island group. We also made visual estimates of overall 

 canopy height, percentage canopy closure, and percentage 

 of forested area. Slope grade, aspect, and elevation were 

 measured on site or from topographic maps. Distance from 

 the ocean was measured from aerial photographs. Each site 

 was classified as either exposed coastline, semi-protected in 

 a bay, or at the head of a bay. 



Study Design Sampling and Analyses 



The Naked Island group was surveyed between 10 June 

 and 11 August 1991 (n = 69 sites). Sites in western Prince 

 William Sound were surveyed between 15-18 July 1991 (n = 

 9) and 12 June-3 August 1992 (n = 68). Afognak Island was 

 surveyed from 4 June-5 August 1992 (n = 76). Kenai Fjords 

 National Park was surveyed from 8-29 July 1993 (n = 40). 

 We surveyed Marbled Murrelet activity and recorded weather, 

 survey period, and topographic and vegetation variables at 

 each survey site in the four study areas. Murrelet activity is 

 highly seasonal and generally exhibits a pattern of peak 

 activity during the breeding season (Hamer and Cummins 

 1991, Nelson 1989, Rodway and others 1993b). Therefore, 

 survey period was categorized as early and late (before or 

 after 10 July, respectively), based on activity patterns 

 previously documented in Prince William Sound (Kuletz 

 and others 1994c). Study designs and survey methods varied 

 among areas (for details see Kuletz and others 1994b, c). At 

 Naked Island, sites were randomly selected equally among 

 four forest types (Kuletz and others, in press), with 69 of the 

 sites having sufficient habitat data to include in this study. In 

 western Prince William Sound, 77 sites were randomly 

 selected from available habitat, although sample sizes among 

 habitat types were not equal. Forty-six surveys were done 

 from an anchored vessel, 23 from shore locations, and eight 

 upland. An additional nine upland sites were surveyed 

 opportunistically in 1991 . These sites were located in forested 

 and nonforested habitat, and occurred in areas of western 

 Prince William Sound not previously surveyed. Sampling at 

 Kenai Fjords National Park was randomly stratified by forested 

 versus unforested and bay head versus not bay head. The 38 

 survey sites were equally distributed among the strata; 21 



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



143 



