I would like to submit a portion of the Birds of North America species account on White-winged Scoters for those who are interested. This would be the definitive summary on this species. For those interested, it will make a good read. But warning, it is long. It highlights a little bit more about their demography and threats to the species.

Enjoy and hope those who are interested find it useful.

Jeff Kozma
Yakima

Demography:

Little information on density. On nesting area at Redberry Lake,
Saskatchewan, densities ranged from 0.06 to 0.60 scoter pair/ha (Brown
1981, Brown and Fredrickson 1989). Density of breeding pairs on Jessie
Lake, Alberta, was 0.10 pair/ha in 1976 (Brown 1977, Brown and Brown
1981). In 2 European studies, densities ranged from 0.49 pairs/ha of
land area (Hild?n 1964) to 18 pairs/ha. These sites were chosen for
study because of their high densities, so they are not representative of
densities throughout most of the European range, which may be much
lower.

On wintering areas in coastal British Columbia, densities averaged 3.1
and 1.1 birds/km of shoreline in Nov and Mar, respectively (Vermeer and
Bourne 1984). Along New Hampshire and Massachusetts coasts, densities
ranged from 50.8 birds/km on sandy habitat to 0.62 bird/km on rocky
headlands (Stott and Olson 1972a, 1972b).

Surveys of breeding waterfowl conducted by USFWS sample large portion of
breeding grounds of the 3 species of scoters in North America. Because
these species are difficult to identify from the air, counts of all 3
scoters are pooled. Thus, deriving accurate estimates for individual
species is impossible. Furthermore, large areas of boreal forest habitat
are sampled where visibility indices are poorly developed.

Continental estimate for White-winged, Surf, and Black scoters is
1,990,000 for period 1970-1979 (USFWS and CWS 1986). On basis of similar
data for period 1955-1973, Bellrose (1980) calculated average yearly
total scoter summer population of 1.48 million for Alaska, the open and
closed boreal forest region, and the parklands and grasslands of w.
Canada. White-winged Scoter component of this number probably is between
555,000 and 675,000 (Bellrose 1980).


Trends

Mean scoter population for all 3 species was estimated at 2.02 million
for 1957-1961, 1.32 million for 1962-1966, and 1.35 million for
1967-1971, with pronounced decline in s. Manitoba (Bellrose 1980).
Midwinter inventories of all 3 species of scoter showed declining
populations from 1954 to 1994; because numbers are combined for the 3
species, no trend is clear for White-winged Scoter (Kehoe et al. 1994).
Although White-winged Scoters commonly nested in s. Manitoba in 1940s
(Rawls 1949), they have been absent there since the 1960s.

EFFECTS OF HUMAN ACTIVITY
Shooting and trapping

Sea duck hunting has rich history in coastal areas of New England, and
increasing numbers of hunters are becoming involved with the sport
because of long seasons and liberal bag limits compared with those in
place for Black Duck (Anas rubripes) and other waterfowl species hunted
for sport. Evaluation of effect of hunting on White-winged and other
scoters is difficult because information gathered on these populations
(wing collections, hunter mail questionnaires, band recovery data, and
annual invetories) is inadequate.

Total continental annual harvest of all 3 species of scoters averaged
126,700 for 1971-1975, 116,500 for 1976-1980, and 98,900 for 1981-1985
(USFWS 1988). Generally, about half the harvest occurs in U.S. and half
in Canada. In North America, all 3 species of scoters accounted for
0.3-0.5% of all waterfowl killed (USFWS 1988).

For the three 5-yr periods from 1971 to 1985, annual average hunting
kill for all 3 species of scoters in Canada was 58,133 (mean 51% of
total kill, range 44.5-57.6) and in U.S., 55,900 (mean 49%, range
42.4-54.45; USFWS 1988). In states of the Atlantic Flyway, annual
average harvest of White-winged Scoters was 17,320 (range 6,600-32,100)
for 1961-1986 (USFWS 1988). White-winged Scoters accounted for 29.9% of
sea duck harvest 1961-1986 (USFWS 1988). During this time, White-winged
Scoters were the most common sea duck killed in 14 yr and second most
common in 6 yr. Number harvested and rank in harvest of sea ducks
declined after 1976 (USFWS 1988).

Relative distribution and abundance of all 3 scoter species on Atlantic
Coast may have been influenced by hunting (Stott and Olson 1972b).
Whether hunting harvest played role in what seems to be reduction in
Atlantic coastal population remains to be determined. Data available are
inadequate to determine population status of White-winged Scoters or
influence of harvest (Stott and Olson 1972a, 1972b).


Toxic contaminants

Feeds heavily on blue mussel, a species known to concentrate toxic
chemicals (Goldberg 1975); thus should be good environmental indicator
of pollution in marine habitats (Vermeer and Peakall 1979). Individuals
collected in Chesapeake Bay had high levels of lead and cadmium (Scanlon
et al. 1980, Di Giulio and Scanlon 1984). One of 4 birds collected in
Chesapeake Bay had levels of mercury (0.61 ppm) that exceeded
recommended 0.50 ppm action level set by U.S. Food and Drug
Administration for mercury in fish and shellfish (Baskett 1975). Eight
White-winged Scoters collected from n.-central New York State had
measurable levels of polychlorinated biphenyls (PCB; <40.2 micrograms/g
of body tissue) in liver, muscle, and brain tissue (Baker et al. 1976).
Trace-metal levels were low enough that no toxicological effects were
expected. Because of similarities in food and migratory habitat, levels
of PCB in scaup and scoters could be combined to establish presence of
PCB contamination in their habitats (Baker et al. 1976).


Degradation of habitat

Throughout northern prairies and aspen parkland areas of North America,
intensification of agriculture has eliminated important nesting
habitats. The characteristic of nesting long distances from water in
dense, often thorny, vegetation puts this species in jeopardy, because
this preferred nesting habitat is among the first eliminated. Further,
use of pesticides and agricultural chemicals has increased, and it has
potential to greatly reduce quality of these wetlands for waterfowl
(Grue et al. 1988). White-winged Scoters have been eliminated from
nesting areas in southern prairies (see Distribution: the Americas,
above); whether this has occurred because of habitat degradation,
disturbance during nesting, excessive harvest on local breeding areas,
or some combination of these factors is unknown.

White-winged Scoters are among the most vulnerable sea birds to oil
spills because the species often occurs in high densities along oil
transportation routes (Vermeer and Anweiler 1975, Vermeer and Vermeer
1975, King and Sanger 1979). Extensive oil spills may eliminate entire
wintering populations. Long-term disruption of food supplies could have
more serious effects on populations than the more spectacular deaths
occurring directly from oiling. Contamination of the most productive
bays and estuaries where scoters winter could reduce scoter populations
and populations of other wintering waterfowl (Ohlendorf and Fleming
1988).


MANAGEMENT

Vulnerable to hunting because it nests late and has long brooding period
(Rawls 1949, Brown and Brown 1981), and because many ducklings do not
reach flight stage until after beginning of hunting season in w. Canada
and Alaska (Brown and Brown 1981). Although not preferred by hunters,
vulnerable to overharvest on breeding areas. Protection of breeding
populations close to human settlement may be needed to ensure future of
local breeding populations. Because females are strongly philopatric to
natal areas, reoccupation of areas where populations have been
eliminated is likely to be slow. Low annual recruitment, delayed
maturity, and lack of renesting attempts also are likely to hinder
recovery of extirpated populations (Hochbaum 1946).

To improve management of this species, better information is needed
about population status and harvest. Because counts of all 3 North
American scoters are routinely pooled, data taken from aerial surveys
are extremely variable; 6.5-75.8% of the population would likely be
counted (Stott and Olson 1972a). Current midwinter aerial survey-1
sample census of scoter populations conducted each winter-is inadequate
to provide reliable information concerning population status. Data that
are needed to establish recruitment and survival rates (e.g., band
recoveries, measures of recruitment on nesting areas) also are limited.
Samples of scoters taken for contaminant analysis have been remarkably
few, and further monitoring is needed in this area.