NPWRC :: Ecology and Management

			Number of
Species/subspecies	Habitat	Location ^b	Study years	Nests	Mortality rates^c	Mortality causes^d	Source
Trumpeter Swan	Forest/delta Intermountain marsh/lake	Alaska (1) Mont.	4 3	134 101	0.24 (0.14 - 0.40) 0.24	O,^e P, a, w A	Hansen et al.(1971)^f,g Page (1974) in Bellrose (1980)
White-fronted Goose	Tundra	Alaska (2)	7	179	0.25 (0.13-0.52)	p-P, w-W, a, o	Combined results of Mickelson (1975) and Ely and Raveling (1984)^h
Snow Goose
Lesser	Tundra Tundra Tundra	N.W.T.(3) N.W.T.(4) N.W.T.(5)	8 2 2	3,949 252 427	0.21(<0.01-1.00)ⁱ 0.57 (0.29-0.84) 0.17 (0.14-0.19)	Varied^j (P,W,A) P O,^e p	Barry (1967) Kerbes (1969) Combined results of Ryder (1971) and McLandress (1983)g,k
Greater	Tundra	N.W.T.(4)	1	52	0.33	A, p	Lemieux (1959)
Ross' Goose	Tundra	N.W.T.(5)	6	1,441	0.16 (0.03-0.22)	P, o-O, a	Combined results of Ryder (1967, 1972) and McLandress (1983 )k
Emperor Goose	Tundra	Alaska (2)	7	449	0.11 (0.00-0.32)	P, o-O,^e a	Combined results of Mickelson (1975) and Eisenhauer and Kirkpatrick (1977)^l
Canada Goose
Western/Giant	Mixture	9 western provinces and states	158	18,231	0.29^m(0.12-0.76)	P-P, A-A, w-w,o	From review by Krohn and Bizeau (1980)
	Parkland Parkland Forest bog lakes Reservoir	Alb. Man. Mich. Mo.	3 3 3 4	334 542 643 256	0.48 (0.31-0.73) 0.25 (0.18-0.35) 0.35 (0.30-0.41) 0.35ⁿ	A-A, p-P, o-O A-A, p-P, w-W, o-o P, a-a P, W, o	Ewaschuk and Boag (1972) Cooper (1978) Sherwood (1968) Brakhage (1965)
Todd	Forest/ Tundra edge	Ont., Man.	5	397	0.17 (0.04-0.22)	P, o-o, a	Combined results of Pakulak (1969) and Raveling and Lumsden (1977)
Dusky	Forest delta Forest delta	Alaska (1) Alaska (1)	1 10	222 ?	0.20 0.52 (0.21-0.81)	O, W, a, p See source	Trainer (1959)f Comely et al. (1985b)
Lesser/Hutchins	Tundra	N.W.T.(6)	7	418	0.12 (0.06-0.17)	P	MacInnes et al. (1974)^o
Cackling	Tundra	Alaska (2)	7	919	0.26 (0.11-0.36)	P, o-O,e a	Combined results of Mickelson (1975) and Eisenhauer and Kirkpatrick (1977)^l
Brant	Tundra Tundra	N.W.T.(3) Alaska (2)	8 11	3,308 1,900	0.23 (0.03-0.71)ⁱ 0.39 (0.03-0.86)	Varied^j (P,W,A) Varied^j (P,A,W,0e)	Barry (1967) Combined results of Mickelson (1975), Eisenhauer and Kirkpatrick (1977), and Eisenhauer (1977)^l
^aAll studies report apparent rates and may therefore underestimate actual mortality rates, although many studies include nests found after they were destroyed (see text and Ely and Raveling 1984 for discussion of use of apparent mortality rates for geese).
^bNumber in parentheses refers to location shown on Figure 12-1.
^cUnweighted average from all years unless noted otherwise; range for different years is in parentheses.
^dMortality-cause codes are: P = predation, A = abandonment, W = weather, and 0 = other/undetermined. Letter styles reflect calculated or implied proportions of mortality ascribed to each cause as follows: capital letter = major factor (> 50%), italicized capital letter = moderate factor (> 25-50%), lowercase letter = limited factor (> 10-25%), lowercase italicized letter = minor factor (≤ 10%).
^eOther/undetermined categories likely caused mainly by predation.
^fMortality-cause data based on percentage of eggs destroyed and not percentage of nests destroyed, and thus the other/undetermined category includes infertile eggs, dead embryos, eggs buried in nest, or eggs that were found outside nest or were missing.
^gMortality-cause data are from 1 year only.
^h Mortality-agent data based on eggs in Mickelson (1975) and nests in Ely and Raveling (1984).
ⁱAdds total loss of Snow Goose nests and 50% of Brant nests caused by snowstorm that were not reflected in Barry's (1967) tabular data on nest success; additional losses to grizzly bears occurred in 1 year but could not be related to tabular data.
^jRelative importance of mortality causes varied among years; maximum effects of individual causes in a study year are in parentheses.
^kMortality-cause data from Ryder (1971 [Snow Geese]) and Ryder (1967, 1972 [Ross' Geese]) except note of abandonment by McLandress (1983).
^lMortality-cause data based on eggs in Mickelson (1975) and nests in other studies and exclude losses to subsistence hunters and desertion caused by people including subsistence hunters.
^mUnweighted average of 33 studies, but the separate studies were presented as weighted averages in Krohn and Bizeau (1980, Table 27).
ⁿWeighted average.
^oFrom nests with complete clutches being incubated; some additional losses caused by desertion, flooding, and predation that occurred before nests were monitored were not included.


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Mortality During the Breeding Season

Table 12-2. Some Mortality rates of Swan and Goose Nests in North America and Principal Causes of Mortality^a

Mortality During the Breeding Season

Table 12-2. Some Mortality rates of Swan and Goose Nests in North America and Principal Causes of Mortalitya

Table 12-2. Some Mortality rates of Swan and Goose Nests in North America and Principal Causes of Mortality^a