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Harlequin Ducks in the Eastern United StatesAuthor(s): Glen H. MittelhauserSource: Waterbirds, 31(sp2):58-66. 2008.Published By: The Waterbird SocietyDOI: http://dx.doi.org/10.1675/1524-4695-31.sp2.58URL: http://www.bioone.org/doi/full/10.1675/1524-4695-31.sp2.58

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58

Harlequin Ducks in the Eastern United States

G

LEN

H. M

ITTELHAUSER

Maine Natural History Observatory, 317 Guzzle Road, Gouldsboro, ME 04607 USAInternet: purplesandpiper@gmail.com

Abstract.—

Harlequin Ducks (

Histrionicus histrionicus

) arrive along the eastern coast of the United States at tra-ditional wintering grounds from late September to December through early January. Counts in January and Febru-ary best represent wintering bird numbers. Spring migrants depart from April to May, although from moresoutherly wintering areas, birds appear to depart in March. Breeding has never been confirmed in the eastern Unit-ed States. Molting females have been documented in Maine during the fall, but the extent of molting has not beenassessed. It is estimated 1,575 to 1,800 Harlequin Ducks wintered in the eastern United States from Maine to NorthCarolina between the winters of 1997-98 and 2001-02. Over 75% of the birds wintering in the eastern United Stateswere in Maine, primarily in the vicinity of Isle au Haut. Smaller concentrations representing about 18% of the win-tering birds in the eastern United States were at locations in Massachusetts and Rhode Island, primarily the CapeAnne region and Martha’s Vineyard, Massachusetts and the Sachuest Point region, Rhode Island. South of RhodeIsland, Barnegat, New Jersey is the only area that regularly reports counts of over 25 birds. In the Isle au Haut regionof Maine, numbers along survey routes have not shown a linear change from 1989-2002, but show a pattern of de-cline from 1989 to 1993 followed by increases since then. In eastern Maine, population increases are greatest andbirds are expanding their winter range into new areas. All other areas in the eastern United States south of Isle auHaut that regularly report over 50 birds show significant population increases since the 1980s, north-eastern US.

Key words.—

Harlequin Duck,

Histrionicus histrionicus

, population status, migration.

Waterbirds 31(Special Publication 2): 58-66, 2008

Harlequin Ducks (

Histrionicus histrionicus

)along the eastern coast of the United Statesare part of the eastern North American win-tering population that includes birds in east-ern Canada from Newfoundland to NewBrunswick (Robertson and Goudie 1999).The wave-exposed rocky shorelines in theUnited States from Maine to New York havebeen known to hold wintering populationssince at least the early 1800s (Langille 1884;Eaton 1910; Palmer 1976). These ducks wereonce reported as common in this region(Coues 1883; Langille 1884; Norton 1896;Forbush 1912, 1925; Forbush and May 1955;Goudie 1989), but by the early 1900s the spe-cies was nearly extirpated (Norton 1896;Knight 1908; Forbush 1912). Concerns overthe eastern North America population in-creased in the 1980s when fewer than 1,000individuals were estimated in the populationand declines were again noted (Vickery 1988;Goudie 1991; Montevecchi

et al

. 1995).In this paper the current knowledge of

Harlequin Duck numbers and distributionin the eastern United States is summarized,trends in wintering numbers across the re-gion are assessed, and threats to populationrecovery and health are described.

M

ETHODS

Information from the following sources were com-piled: survey results in Maine (see Mittelhauser

et al

.2002) and Sachuset Point National Wildlife Refuge inRhode Island (N. Kline, Sachuest Point NWR, unpub-lished data), numbers reported during Christmas BirdCounts (CBC) at coastal locations from Maine to Flori-da (1950-2002), and additional counts published inNorth American Birds (formerly Audubon Field Notes,Field Notes, National Audubon Society Field Notes, Au-dubon Field Notes, and American Birds) or other sourc-es (Bailey 1955; Vickery 1988; Zeranski and Baptist1990; Goudie 1991; Veit and Petersen 1993; Montevec-chi

et al

. 1995; Mittelhauser 2000, 2001; Thomas andRobert 2001; Mittelhauser

et al

. 2002; Caron and Paton2007; McKinney

et al

. 2007).Counts at Isle au Haut and outer Jericho Bay, Maine,

conducted annually since 1989, were designed to assessHarlequin Duck numbers. Although some years are rep-resented by few counts (Mittelhauser 2001), surveymethodology at these sites has been similar throughoutall surveys (Mittelhauser 1989, 2000; Mittelhauser

et al

.2002). Additional locations in Maine have also been pe-riodically surveyed (see Mittelhauser

et al

. 2002). FromMassachusetts to Rhode Island, surveys have recentlybeen conducted. During the winters between 2001 and2003, McKinney

et al

. (2007) surveyed twelve locationsin Massachusetts and Rhode Island known to regularlysupport wintering birds. The southern coast of RhodeIsland within Narragansett Bay was also surveyed during2005 and 2006 (Caron and Paton 2007). Counts at Sa-chuest Point NWR, conducted monthly by volunteerssince 1985, were designed to monitor various waterbirdsadjacent to the refuge, and Harlequin Ducks have beenregularly observed and recorded during these surveys(N. Kline, Sachuest Point NWR, pers. comm.). For the

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remainder of the eastern United States, CBC data andother published records were used to determine distri-bution and abundance of birds. Because there has beenno region-wide survey of Harlequin Ducks in the east-ern United States, maximum mid-winter counts wereused to estimate regional abundance between the win-ters of 1997-98 and 2001-02. Because winter observa-tions of this species are often hampered by adverseweather and sea conditions and surveys rarely cover allpotential habitat, maximum regional counts, ratherthan mean or median counts, were thought to better re-flect the minimum number of birds present. To assesspopulation trends at key wintering locations LOESSsmoothing was used (a locally weighted nonparametricregression method, Neter

et al

. 1996) to explore regres-sion relationships. Spearman rank order correlation co-efficients (r

s

) were used to correlate count with year andtest the significance of a trend (see Fowler and Cohen1996). The Kruskal-Wallis test (H

(N1, N2, N3)

was used totest for monthly differences in counts (Conover 1980).A critical P of 0.05 was used throughout.

D

ISTRIBUTION

AND

ABUNDANCE

Breeding

Boardman (1862) reported HarlequinDucks (apparently disabled) occasionallybred on coastal islands in eastern Maine, al-though there has been an unresolved dis-pute about the validity of this and other ear-lier coastal breeding records in the region(Brewer 1852; Coues 1883; Norton 1896;Phillips 1925; Pettingill 1939; Palmer 1949;Squires 1952). Since 1950, at least 20 lonesummering birds have been recorded atcoastal wintering sites from Maine to Chesa-peake Bay, and during the summer of 2003 apair of birds was observed occasionallythroughout the summer around an islandnear Isle au Haut; none of these summerrecords have included evidence that suggestbreeding.

Migration

Fall migrants arrive earlier in Maine thanat wintering sites further south. In Maine theearliest fall record is during the last week ofSeptember 1999 when eight birds were ob-served at Isle au Haut. By mid-October, num-bers have increased slightly and males usual-ly outnumber females (e.g., 87 birds at Isleau Haut on 18 October 1998; 69% male). Bylate October, numbers have increased toabout half of typical winter counts (e.g., 471

birds at Isle au Haut, outer Jericho Bay, andthe Vinalhaven area on 27 October 1999).Counts at Isle au Haut do not differ fromJanuary to March (H

13, 16, 12

= 3.78, P = 0.15).The maximum winter counts, for eachmonth at Isle au Haut are 248 (7 January1989), 237 (21 February 1999), and 253 (28March 1999). Based on observations ofmarked birds, individuals present at Isle auHaut in November and December tend toremain and are observed numerous timesthroughout the winter until spring migra-tion. In the spring, numbers diminish quick-ly during the first two weeks in April and areat about half of typical winter counts by lateApril (e.g., 111 at Isle au Haut on 26 April1998). By early- to mid-May birds are stillpresent and immature birds tend to be in themajority (e.g., 28 birds at Isle au Haut on 16May 1990, 50% male, 71% of males were im-mature). An unverified report of a flock of300 birds one evening in a cove at Isle auHaut on 5 May 1995 may represent stagingprior to migration or resting north-boundmigrants. Observations of birds during June(e.g., three birds at Isle au Haut on 19 June1999) may represent summering birds orlate north-bound migrants.

At Sachuest Point, Rhode Island, wherecounts have been conducted monthly since1985, the first fall migrants typically arriveduring the last two weeks of October (e.g.,no birds detected on 14 October 2001, elev-en birds on 30 October 1988), althoughthere is an early report of one bird duringlate September 1999. By early- to mid-No-vember, birds have increased to about halfof typical winter counts (e.g., 41 birds on 11November 1999). Counts of birds at Sa-chuest Point do not differ from January toMarch (H

20, 24, 22

= 0.52, P = 0.77). The max-imum winter counts, by month, at SachuestPoint NWR are 110 (January 1995), 105 (7February 1999), and 85 (March 1998). Inthe spring, average departure is during thesecond two weeks of April, and there havebeen no May records since 1985. Observa-tions of birds in June (e.g., one bird east ofSachuest Point on 5 June 1979) may repre-sent summering birds or late north-boundmigrants.

60 W

ATERBIRDS

South of Rhode Island, the first fall mi-grants typically arrive by late October or No-vember (e.g., six at the Chesapeake BayBridge Tunnel on 21 October 1994, one atOregon Inlet, North Carolina on 29 Novem-ber 1993), although earlier records are occa-sionally reported (e.g., three at Sandy Hook,New Jersey on 4 October 1999). Counts ineach winter month are not often reported inthis region, but counts between late Decem-ber and February likely represent winteringbirds. During spring, birds typically departbetween March and mid-April (e.g., threewintering birds at Chesapeake Bay BridgeTunnel stayed until 24 April 1993; of 15 win-tering birds at Barnegat, New Jersey duringthe winter of 2000-01, “several” stayed untillate March), although stragglers may departmuch later (e.g., of the 15 wintering birds atOcean City, Maryland during the winter of1998-99, the last departed on 2 May 1999).Observations of birds during June have beenreported from Connecticut to Virginia (e.g.,one bird at Norwalk, Connecticut on 6 June1983 (Zebranski and Baptist 1990) and onebird at Chesapeake Bay Bridge Tunnel on 8June 1997) and may represent summeringbirds or late north-bound migrants.

Wintering

The number and distribution of winter-ing Harlequin Ducks in Maine is summa-rized by Mittelhauser

et al

. (2002). In sum-mary, five regions in Maine have large andconsistent concentrations of wintering birds:Sally Islands (from Jordan’s Delight to Cran-berry Point, Corea), outer Jericho Bay (fromHeron Island to Black Horse), the southernshoreline of Isle au Haut, the Vinalhaven ar-ea (from Otter to Brimstone Islands), andYork County (East Point to Ogunquit;Fig. 1). Annual counts have been conductedin each of these areas (Table 1) except at theSally Islands area where only occasional win-ter surveys have been conducted. Occasionalcounts of over 50 birds have been recordedat Seal Island, Maine in outer Penobscot Bay,although numbers here have been inconsis-tent and ranged from zero to 61 birds duringthe few winter surveys in the past ten years

(Mittelhauser

et al

. 2002). Surveys during thewinter of 2004-05 on the eastern Maine coastsuggest an additional concentration fromLubec to Cutler where 59 birds were ob-served. Because the number of birds ob-served in Maine during offshore surveys byboat was often hampered by adverse weatherand sea conditions (Mittelhauser

et al

. 2002),peak counts in areas supporting birds (1,294birds), rather than mean (1,091 birds) ormedian (1,083 birds) counts, were thoughtto better reflect the number of HarlequinDucks present in Maine, leading to an esti-mate of 1,200 to 1,300 birds wintering in thisregion between 1997-98 and 2001-02 (seeMittelhauser

et al

. 2002). Because winter sur-vey data are sparse for portions of the north-eastern and southwestern coast of Maine, ad-ditional wintering birds may be present fromCutler to Milbridge and the offshore islandsalong the southwest coast from MuscongusBay to the New Hampshire border (Mittel-hauser

et al

. 2002).South of Maine, no region-wide systemat-

ic surveys for Harlequin Ducks have ever

Figure 1. Maximum number and distribution of Harle-quin Ducks in New England in winter (December-March) reported since 1960.

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U.S. 61

been conducted, but based on CBCs andother published counts in the region, over50 birds have been reported at three loca-tions in Massachusetts and Rhode Island(Fig. 1): Cape Anne, Massachusetts (fromAndrews Point, Rockport to Magnolia andGloucester); Martha’s Vineyard, Massachu-setts, and Sachuest Point, Rhode Island(from Beavertail, Jamestown to SakonnetPoint). Monthly counts have been conduct-ed adjacent to Sachuest Point NWR since1985 and counts have been made in this re-gion by McKinney

et al

. (2007) and Caronand Paton (2007). The CBC at Newport,Rhode Island to Westport, Massachusetts al-so covers more of the Sachuest Point region

where birds have been known to range. Amaximum count of 144 Harlequin Ducks oc-curred at this CBC on 19 December 1998whereas the maximum count of birds adja-cent to the Sachuest Point refuge was 110during January 1995. At Cape Anne andMartha’s Vineyard, Massachusetts, CBCs andother published counts were used to esti-mate wintering numbers. At Cape Anne, themaximum count of 116 birds occurred on 6March 2002 and the second highest countwas during the winter of 1999-2000 when 81birds were reported. McKinney

et al

. (2007)report 118 birds here during the winter of2001-02. At Martha’s Vineyard, the maxi-mum count occurred over five years ago

Table 1. Maximum winter counts of Harlequin Ducks (December-March) in the eastern United States 1997-98through 2001-02. Source of counts are from Christmas Bird Counts (CBCs) and other published and unpublishedsurvey data.

Region Count Type

1

Year

97-98 98-99 99-00 00-01 01-02

Outer Jericho Bay, ME Survey 492 676 755 628 633Isle au Haut, ME Survey 237 253 193 204 210Sally Islands, ME

2

Survey (84) (84) (84) (84) 84Sachuest Point, RI Survey

3

112 144 93 119 77Cape Anne, MA CBC 59 66 81 39 118

4

York County, ME CBC 32 45 73 51 86Vinalhaven, ME Survey 39 68 42 37 55Great Wass Is-Cutler, ME

2

Survey (42) 42 (42) (42) (42)Martha’s Vineyard, MA CBC 54 42 33 20 69

4

Nantucket, MA CBC 18 27 26 38 31

4

Barnegat, NJ CBC 15 34 30 22 18Cape Cod, MA CBC 2 8 16 6 8Ocean City, MD CBC 13 15 6 10 1Southern Nassau Co, NY CBC 4 6 9 4 1Montauk, NY CBC 1 4 11 6 2Other CBCs, MA CBC 5 4 4 0 29

4

Marshfield, MA CBC 2 10 2 1 3Other CBCs, ME CBC 2 4 3 6 3Other CBCs, NY CBC 0 5 4 0 5Other CBCs, VA CBC 10 0 0 3 4Other CBCs, DE CBC 4 1 1 0 0Other CBCs, NJ CBC 1 1 2 0 1Other CBCs, MD CBC 0 0 0 1 1Coastal New Hampshire CBC 0 1 0 0 0Other CBCs, NC CBC 0 1 0 0 0Total 1228 1541 1510 1321 1481

1

Surveys were either boat or shore-based; Numbers presented at Christmas Bird Count (CBC) locations repre-sent maximum number based on either CBCs or other published winter counts.

2

Location was not surveyed every year. Number in parentheses are estimated numbers present and were not ver-ified annually by surveys.

3

Location is surveyed annually and also included within the CBC at Newport, RI to Westport, MA.

4

Data from McKinney

et al

. (2007).

62 W

ATERBIRDS

when 101 birds were recorded during theCBC on 25 December 1995, and the secondhighest count occurred here on 11 Decem-ber 1994 when 80 birds were recorded.McKinney

et al

. (2007) report 91 birds hereduring the winter of 2002-03, suggesting thatmaximum numbers at this site are remainingconsistent. Regular but low numbers also oc-cur at Nantucket, Marshfield, and other lo-cations in Massachusetts (Table 1). Duringthe winter of 1998-99, 301 birds were report-ed in Massachusetts and Rhode Island andMcKinney

et al

. (2007) estimated a mean of327 ± 114 from 2001-03 and a maximum of341 birds during 2002-03. Based on a compi-lation of peak winter counts from NewHampshire to Rhode Island between 1997-98 and 2001-02 (Table 1), 300-400 birds areestimated to winter in this region. Becausecounting effort has varied considerably overthe years, especially at more offshore and in-accessible locations, this estimate may un-derestimate the wintering population in thisregion. Although there is no evidence to sug-gest additional large concentrations of birdsin Massachusetts and Rhode Island, unsur-veyed appropriate habitat exists that mayharbor additional wintering birds.

South of Rhode Island, Montauk andSouthern Nassau County in New York,Barnegat, New Jersey and Ocean City Inlet,Maryland are the only areas supporting reg-ular numbers of wintering birds (Fig. 2) andnumbers are reported here during CBCs.Barnegat, New Jersey supports the largestconcentration of birds south of Rhode Is-land with a maximum number reported of34 on 6 February 1999. Fewer than ten birdsappear regularly at the Chesapeake BayBridge Tunnel, although numbers herepeaked at 15 birds during March 1978 (Vick-ery 1988). North Carolina has severalrecords of individuals associated with bridgebreakwaters, and birds are infrequently re-ported as far south as Florida (Williams1968). The peak number of birds in this re-gion occurred during the winter of 1998-99when 67 birds were tallied (Table 1). Basedon a compilation of peak winter countssouth of Rhode Island between 1997-98 and2001-02, 75-100 birds are estimated to winter

in this region. Because of lack of consistentwinter survey efforts in this region, especiallyat more offshore and inaccessible locations,region-wide winter surveys are needed to ver-ify these estimates.

Much remains to be learned about num-bers, distribution, and local movement ofHarlequin Ducks in many areas in the east-ern United States. Because of lack of region-wide winter survey data, it is difficult to reli-ably estimate the population of winteringHarlequin Ducks. In addition, local countsfrom CBCs and other surveys tend to behighly variable from year to year, furthercomplicating the estimation of reliable win-tering population numbers. Combining thepeak winter counts across the region, be-tween 1,575 and 1,800 Harlequin Ducks win-tered along coastal sites from Maine toNorth Carolina between the winters of 1997-98 and 2001-02, but region-wide winter sur-vey efforts are needed to verify these esti-mates. Because winter survey data are sparsefor portions of the Maine coast (Mittelhaus-er

et al

. 2002) and some offshore locationssouth of Maine, this estimate likely does notoverestimate the wintering population andmay still underestimate the number of win-tering birds in the eastern United States.During the winter of 1998-99, 1,541 Harle-

Figure 2. Maximum number and distribution of Harle-quin Ducks in the mid-Atlantic states in winter (Decem-ber-March) reported since 1960.

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quin Ducks were counted at wintering loca-tions from Maine to North Carolina (Table1) and is the largest number ever recordedin the eastern United States. Of these winter-ing birds, 1,172 (78%) were at wintering sitesin Maine, one bird in New Hampshire(<1%), 157 birds (10%) in Massachusetts,144 birds (8%) in Rhode Island, and 67 birds(4%) were at scattered locations furthersouth from New York to North Carolina.

Molt

The importance of the eastern UnitedStates to molting Harlequin Ducks has notbeen adequately assessed. Early fall migrantsin Maine may include some molting adult fe-males. At least one flightless female was ob-served in a flock with seven other females atIsle au Haut on 2 October 1999 and twoflightless adult females were captured thereon 20 November 1997. Occasional summer-ing birds in the region also molt on thecoast. A male observed at the ChesapeakeBay Bridge Tunnel on 8 June 1997 likely re-mained in the area and was observed duringprebasic molt at the same location on 18 July1997.

Population Trends

In the eastern United States, counts ofHarlequin Ducks appear to have increasedsteadily since at least the 1980s in all areas ex-cept the Isle au Haut region, Maine. Trendsin Harlequin Duck numbers in Maine are as-sessed by Mittelhauser

et al

. (2002). In sum-mary, counts of birds at Isle au Haut and ad-jacent areas have not changed in a linearmanner from 1989-1999, although numbersin this area show a pattern of decline from1989 to 1993 followed by increases sincethen (Mittelhauser

et al

. 2002). From 1989 to2002, there is no evidence of significant lin-ear trends in the number of birds counted atIsle au Haut (r

s

= 0.14, N = 41, P = 0.43) or ad-jacent islands (r

s

= 0.11, N = 27, P > 0.50), al-though a dip in numbers in the early 1990s,similar to those reported at Canadian winter-ing sites (Mittelhauser 2000), is evident(Figs. 3a and 3b). Surveys during the winter

of 2004-05 in eastern Maine documentedcontinuing increases in wintering popula-tions. In the Sally Islands area, their rangeexpanded into new areas and 192 birds werecounted here between 30 December 2004and 4 January 2005. The coast from Cutler toLubec also suggests an increasing popula-tion expanding their typical range as 42birds were counted here on 12 January 2005.At Sachuest Point NWR, counts of HarlequinDucks adjacent to refuge lands have in-creased since 1985 (Fig. 3c) during January(r

s

= 0.68, N = 19, P = 0.002) and February (r

s

= 0.77, N = 18, P < 0.001). Increases herewere not noted during counts in December(r

s

= 0.45, N = 18, P = 0.06) or March (r

s

=0.28, N = 17, P = 0.29). In Rhode Island theexact timing of December or March surveysis important as counts in early December orlate March may miss late fall migrants or ear-ly spring departing birds. During late De-cember CBCs at Newport, Rhode Island,which includes the Sachuest Point NWR ar-ea, the numbers of birds have increased(Fig. 3c) since 1980 (r

s

= 0.90, N = 23, P <0.001), as has the number of birds observedper hour of effort (r

s

= 0.90, N = 23, P <0.001). Caron and Paton (2007) show a de-clining population wintering at SachuestPoint after the winter of 2000 and suggestthis decline coincided with the appearanceof 20 or more birds at the nearby BeavertailState Park. Population increases are evidentduring CBCs at other wintering locations inthe eastern United States since 1980 basedon actual counts (CNT) and the number ofbirds observed per hour of effort (EFFORT):at York County, Maine (Fig. 3d; CNT, r

s

=0.75, N = 21, P < 0.001; EFFORT, r

s

= 0.61, N= 21, P = 0.005); at Cape Anne, Massachu-setts, (Fig. 3e; CNT, r

s

= 0.89, N = 23, P <0.001; EFFORT, r

s

= 0.87, N = 23, P < 0.001);at Martha’s Vineyard, Massachusetts (Fig. 3f;CNT, r

s

= 0.76, N = 23, P < 0.001; EFFORT, r

s

= 0.62, N = 23, P = 0.002); at Nantucket, Mas-sachusetts (Fig. 3g; CNT, r

s

= 0.86, N = 23, P <0.001; EFFORT, r

s

= 0.86, N = 23, P < 0.001),and at Barnegat, New Jersey (Fig. 3h; CNT, r

s

= 0.90, N = 23, P < 0.001; EFFORT, r

s

= 0.84,N = 23, P < 0.001). Population trends before1980 are more difficult to interpret because

64 W

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Figure 3. Trends in numbers of Harlequin Ducks at (A) Isle au Haut, ME, (B) Spoons and Horses, ME, (C) SachuestPoint, RI, (D) York County CBC, ME, (E) Cape Anne, MA, (F) Martha’s Vineyard CBC, MA, (G) Nantucket CBC,MA, and (H) Barnegat, NJ. Loess smoothing was used to summarize trends. Data from Isle au Haut, ME, Spoonsand Horses, ME, and Sachuest Point, RI are from shore-based or boat surveys; data from the remaining locationsare based on Christmas Bird Counts and other published numbers.

H

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of little information and lack of survey de-tails. Counts at Martha’s Vineyard, the onlyarea with sufficient historical data, suggest adeclining population from the 1930s to the1970s or 1980s (Fig. 3f).

K

NOWN

AND

P

OTENTIAL

T

HREATS

T

O

P

OPULATION

R

ECOVERY

/H

EALTH

Thomas and Robert (2001) summarizepotential limiting factors and threats to Har-lequin Duck recovery and health in the west-ern Atlantic and all are potential conserva-tion concerns in the eastern United States.In summary, they suggest that potentialthreats to birds on wintering grounds in-clude illegal hunting, environmental con-tamination through oil spills and other con-taminants, habitat degradation from nearshore commercial fishing, aquaculture, andseaweed harvest, human disturbance, andcoastal development.

These threats in eastern United Statesare intensified by the strong commitment ofHarlequin Ducks to few traditional winteringsites. The greatest threat to wintering birds islikely from the potential of spills of oil orother contaminants. A major route taken byoil tankers into Penobscot Bay, Maine runsadjacent to the Isle au Haut area and anywinter spill along this route will likely affecta large percentage of the eastern NorthAmerican population. Although small spillshave occurred throughout the eastern Unit-ed States, no oiled Harlequin Ducks have yetbeen reported. Since Harlequin Ducks wereremoved from the list of legally hunted wa-terfowl in the Atlantic Flyway during 1989,few birds have been reported to be killed byhunters in the region and likely does not ex-ceed a few birds a season region wide.

K

NOWLEDGE

G

APS

Few surveys have been conducted in east-ern North America to document the num-ber of wintering Harlequin Ducks with theexception of the Isle au Haut region inMaine and other coastal regions with easy ac-cess for birders. Given the Harlequin Duckspreference for offshore wintering grounds,

coordinated surveys in these isolated areasare needed to fully document and verify win-tering numbers. In addition, numbers ofbirds at the most important wintering sitesshould be monitored at regular intervals toverify that population levels continue to in-crease until the eastern North Americanpopulation reaches viable levels.

A

CKNOWLEDGMENTS

I thank E. Morrison, J. Drury, P. Corr, D. Kausen,M. Lovit, and Petit Manan National Wildlife Refuge fortheir untiring dedication to counting Harlequin Ducksin Maine and C. West, S. Bockian, P. Coleman,J. Smolek, and E. Hinckley for their assistance in com-piling distribution data. N. Kline of Sachuest Point Na-tional Wildlife Refuge, and R. Palmer generously shareddata on wintering Harlequin Ducks. Portions of thisstudy or recent surveys were financially supported bythe U.S. Fish and Wildlife Service, Maine Outdoor Her-itage Fund, National Park Service, Acadia NationalPark, Maine Department of Inland Fisheries and Wild-life, University of Maine, Eastern National Parks andMonuments Association, and Canadian Wildlife Ser-vice. This manuscript was improved by the helpful com-ments of B. Allen, G. Haas, G. Robertson, and L. Tudor.

L

ITERATURE

C

ITED

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Brewer, T. M. 1852. A few ornithological facts, gatheredin a hasty trip through portions of New Brunswickand Nova Scota, in June 1850. Boston Journal of Nat-ural History 6: 299-308.

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Fowler, J. and L. Cohen. 1996. Statistics for Ornitholo-gists. BTO Guide 22. British Trust for Ornithology,Thetford, United Kingdom.

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