LOWLAND-TALL PLANT 
ASSOCIATION 
NORTHWEST POINT 


UPLAND 
SHORT PLANT; 





SOUTHWEST = 
POINT 
Tkm SOUTHEAST 
POINT 
Corex- fescue | ]Other plant communities 
Wh Moss~ Willow i= Rock Slide 
Fig. 5. Buldir Island, Alaska, showing the distribution of associa- 
tions and plant communities. 
+ Beach rye - umbel 
[| Beach rye-umbel- fern 

and 25 May to 2 July 1977. Breeding biology data were col- 
lected from 1974 to 1976 by two to five researchers who 
systematically searched vegetated areas that could be 
reached without technical climbing equipment. In 1977 
four researchers censused sample plots to estimate the breed- 
ing population. 
Canada geese may more readily abandon their nests if 
disturbed during the early part of incubation than if dis- 
turbance occurs later (Hanson and Eberhardt 1971; Cooper 
1978); therefore, after 1974, when we learned the general 
nesting chronology, we conducted searches after geese 
began incubation. Because researchers in other areas 
(MacInnis 1962; Mickelson 1975) have reported that young 
goslings scattered by investigators may be killed by 
glaucous-winged gulls (Larus glaucescens) and parasitic 
jaegers (Stercorarius parasiticus), nest searching was termi- 
nated when it was suspected that clutches were near 
hatching. 
Most nests were discovered either by observing incubating 
geese or by flushing unseen females from nests. Inaccessi- 
ble slopes were scanned from an Avon sport boat moving 
along the base of cliffs, or from land through 20 power spot- 
ting scopes. At nests, the clutch size was recorded, nest ma- 
terial was noted, and at least two eggs in a sample of nests 
were floated to determine the stage of incubation (+3 days) 
by using Westerkoy’s (1950) method as modified for use with 
Canada geese (C. J. Lensink, personal communication). 
Onset of incubation was determined by back-dating. The 
date of clutch initiation was then determined by subtract- 
ing 1 day for each egg in the clutch, plus 1 additional day. 
This laying rate was used because other populations of small 
Canada geese that nest at northern latitudes lay one egg 
per day, but often skip 1 day after egg number four or five 
in large clutches (MacInnes 1962; Mickelson 1975). 

¥ 
Fig. 6. One of the investigators standing in a typical stand of beach 
rye-umbel. Note height of overstory. 
The locations of nests were plotted on 1:25,000 scale 
maps, and 2-m-long stakes were erected 5 m uphill from 
nests to facilitate relocation. Nests were rechecked 2-5 
weeks after projected hatching dates to determine their 
fates. Intact egg membranes that had separated from the 
shells were counted to determine hatching success (cf. 
Mickelson 1975; Bromley 1976). We considered a nest suc- 
cessful if at least one egg hatched, as did Cooper (1978) and 
others, 
Habitat Use 
General Vegetation Analysis 
From subjective observations of plant communities in 
1974, broad plant associations were mapped by walking 
over the island’s surface and locating boundaries with the 
aid of a pocket altimeter and compass. U.S. Geological Sur- 
vey bench marks provided references. Community bound- 
aries were refined in 1975, and the surface area of each 
plant community was calculated by measuring the map 
area with a planimeter and then applying a correction 
factor for slope (determined by estimating the average 
slope in each community with a simple randcm sample). 
In 1975 and 1976 the relative importance (expressed in per- 
