
12 
ple, respective densities were 0.35 and 0.16 nest/ha for these 
two communities. The combined estimate was 0.27 nest/ha 
(Table 5). 
Cooper (1978:34) summarized nest densities of Canada 
geese at different locations. Of 14 mean nest densities, 9 
were lower than Buldir (range 0.02 to 0.25 nests/ha) and 
5 were higher (range 0.52 to 12.36). 
Brood-rearing and Molting Areas 
Soon after hatching, families with Class I goslings (Yocom 
and Harris 1965) moved inland from nest sites to higher 
elevations. Most of these areas were at the upper edge of 
the Lowland Tall-plant association where beach rye-umbel 
and beach rye-umbel-fern communities provided cover and 
sedge-fescue meadows and moss-willow tundra provided 
food. As broods became older, and therefore large enough 
to be safe from predation by gulls and jaegers, families 
gradually moved farther from cover. Some flocks of one 
or two flight-capable adults and one (usually) to four (occa- 
sionally) broods were seen in the upland. It seems that 
flightless adults remained near cover. 
Pre-migrational Use Areas 
During late August and September, Aleutian Canada 
geese used the Upland Short-plant association almost exclu- 
sively. Based on observations of feeding geese and examina- 
tion of droppings and cropped stems in feeding areas, 
favored fall food items appeared to be the fruits of sedge 
(Carex spp.) and crowberry (Empetrum nigrum) and the 
stems of newly emerged, succulent plants of various species. 
The high plateaus (Dry Lake, Extra Plateau, and Foggy 
Plateau) and the area around Kittiwake Pond were major 
feeding areas. 
Kittiwake Pond was frequently used for bathing by flocks 
containing up to 500 birds, including families (occasionally 
with pre-flight goslings) and non-breeders (marked year- 
lings and 2-year-olds not associated with families). Geese 
were seen in salt water only 10 times during the study — 
just before, during, or immediately after the molt when 
the birds were probably losing or gaining flight capability. 
Population Size and Structure 
Production 
Clutch size. — Clutches ranged from two to eight eggs, 
but 82% of them contained five to seven eggs. The overall 
average was 5.6 eggs with only slight variation among years _ 
(Table 6). These clutch sizes may not be exact because our 
first visit to nests occurred after incubation had begun, and 
eggs may have already been lost. Moreover, we did not 
identify or eliminate continuation nests (nests, usually con- 
taining smaller clutches, that were started after first clutches 
are lost; Cooper 1978). These factors probably did not have 
a major effect on our estimate inasmuch as the average at 
Buldir was similar to the highest clutch sizes recorded for 
Canada geese elsewhere (Hanson 1965:165). 
Nesting and hatching success. — Data from 1974 were not 
used to calculate the average nesting and hatching success 
because, due to inadequate marking, we were unable to 
relocate 30% of the nests to determine fates. The proba- 
bility of finding a deserted nest that still contained eggs was 
much greater than finding a successful nest. 
Nesting success in 1975 and 1976 at Buldir was 89 and 
93% , respectively. The overall average (91%) is the high- 
est recorded for wild Canada geese (Table 7). 
In 1975 and 1976 an average of 74.8 % of all eggs hatched 
(Table 8), Hatching in successful nests (80.7%) averaged 
only a little higher than that in all nests. The percentage 
of eggs of unknown fate was higher in 1976 than in 1975, 
accounting for most of the difference in hatching success. 
Fledging success. — Family group counts, conducted from 
19 August to 24 September, were used to calculate the 
fledging success, About four goslings per successful pair of 
geese reached flight stage at Buldir in 1976 (Table 9). This 
Table 6. Frequency distribution and mean of Aleutian Canada goose clutches at Buldir Island, Alaska, 1974-77. 




Number of eggs 1974 1975 1976 1977 Total 
2 1a (02)b 2 (03) 3 (02) 
3 3 (10) 5 (06) 8 (04) 
4 2 (07) 4 (09) 7 (09) 7 (19) 20 (11) 
5 (17) 10 (22) 22 (28) 1 (31) 48 (26) 
6 14 (48) 19 (42) 32 (41) 11 (31) 76 (40) 
7 & (17) 9 (20) 10 (13) 6 (17) 30 (16) 
8 2 (05) 1 (03) 3 (02) 
Total eggs 161 261 419 207 1,048 
Total nests 29 45 78 36 188 
Mean clutch 5.6 + 0.2¢ 5.8 + 0.2 5.4 + 0.1 5.5 + 0.2 5.6 + 0.1 

aNumber of clutches. 
bPercent in parentheses. 
eMean + standard error. 
