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Lesser Scaup Aythya Affinis 679 Ducks_Vol-II-PartIIb.qxd 12/22/2004 5:28 PM Page 679 Lesser Scaup Aythya affinis 679 9.7 eggs (Bengtson 1972b). Incubation, by O alone, of high levels of organochlorine contaminants 26–28 days and starts on completion of clutch. o (Perkins and Barclay 1997) which may have man- usually deserts midway through incubation. Young agement consequences, perhaps even by affecting precocial and nidifugous and, in captivity, weigh thermal properties of plumage as suggested for 38.5 (n ϭ 14). Small crèches sometimes seen. Fledge Lesser Scaup (Stephenson 1997). Use as biomoni- in 40–45 days by which time juveniles independent. tors of metal contamination advocated in US fed- Hatching success in Finland averaged 77% of eggs eral reserves (Cohen et al. 2000). Legal protection laid over 3 years and 6.5% of young reared to fledg- required for most important areas and control of oil ing, but high variation noted between years (Hildén exploration and transport, both terrestrially in Arc- 1964a). Breeds in captivity sometimes in 1st and tic and by sea elsewhere. Hunting legal in 7 coun- usually in 2nd year; not proven in wild. Mean tries of European Union, where 8000 shot annually annual adult mortality of Icelandic birds estimated at in 1980s (Bertelsen and Simonsen 1986)—the 52% (Boyd 1962); longevity record of BTO ringed majority (Ͼ 80%) in Denmark where seaduck bird 8 years 5 months (Toms and Clark 1998). hunting in decline. By early 1990s, numbers shot in Denmark c 1000–3000 (Madsen et al. 1996b) and Conservation and threats currently remain at this level. In Europe, winter populations considered to have unfavourable con- Main threat susceptibility to oil pollution when servation status, although threats localized. Not moulting and in winter. In Caspian Sea, thought to threatened worldwide (Collar et al. 1994). be less numerous than previously because of oil pollution.Also may be susceptible to accumulation John L. Quinn Lesser Scaup Aythya affinis PLATE 24 Fuligula affinis Eyton, 1838, Monogr. Anatidae, wing coverts flecked grey but otherwise as o. Bill p. 157 dark grey; feet and legs as o; eye colour varies with North America age from olive-brown to olive or brownish yellow Etymology: affinis L. for related or allied, pre- (Trauger 1974). sumably in reference to Greater Scaup. Other names: Little Bluebill, Broadbill (also used MOULT: basic or eclipse plumage of o similar to O for Greater Scaup), Dosgris. French: Petit morillon; but more mottled and lacking face patch. Basic Spanish: Pato boludo chico. plumage of O similar to alternate plumage, but face Variation: no subspecies nor geographical varia- patch less distinct than in alternate. o moults into tion in measurements. basic plumage late June–Aug, with heaviest moult- ing July–Aug, quickly followed by pre-alternate Description moult, completed Sept–Oct. O moults into basic ADULT: dimorphic. o in breeding or alternate plumage early Mar–Apr, and into alternate plumage plumage head black with purplish sheen; neck, Aug–Sept. In both sexes, greatest moult intensity breast and upper mantle black; flanks and belly occurs during wing moult in late summer. white; lower mantle grey flecked and ventral region black. In flight, white wing stripe extends across sec- IMMATURE: before first pre-alternate moult resem- ondaries, primaries greyish brown. Bill slaty blue; bles adult O definitive basic plumage, but white face feet and legs grey with darker webs; eye brilliant yel- patch less clearly defined; scapular feathers plain, low. O fuscous to chocolate brown with white patch and underparts paler and browner. Eyes in o yellow, of varying size at base of bill; upper parts darker, in O brownish or greyish olive. Ducks_Vol-II-PartIIb.qxd 12/22/2004 5:28 PM Page 680 680 Lesser Scaup Aythya affinis DUCKLING: upperparts dark olive, with inconspicu- white crescent between black breast and grey sides, O ous dorsal pattern; lowerparts pale yellow-buff, darker has white eye-ring and paler face. Tufted Duck has at side and undertail. Head buff-brownish olive with round head with distinct crest and darker back in bright to buff-yellow cheek and throat; dark eyestripe both sexes. Redhead O has rounder head, paler throat, well defined in front of eye and contrasting with heavy black nail on bill, and grey wing stripe. often bright yellow lores; post-ocular stripe and pale eye-ring usually well marked. Bill of Lesser Scaup Voice smaller, more slender at base and with smaller nail o generally silent,but gives soft calls during courtship, than Greater Scaup. Bill blackish, iris dark olive or when leading Inciting mate during interactions with brownish grey shifting toward greenish yellow. other conspecifics, and during post-copulatory dis- play; O louder and more vocal. Coughing call, fre- MEASUREMENTS AND WEIGHT: from breeding birds quently uttered by oo in display groups, single in Manitoba; see Austin et al. (1998) for summary of whistled whew; Kinked-neck and Head-throw calls of ϭ other locations and periods of life cycle. o (n 40) o faint whee-ooo. O makes repeated low arrr calls while Ϯ Ϯ tail, 47–59 (52.3 0.4); wing, 193–226 (204.8 Inciting during interactions with unpaired oo and Ϯ 1.1); keel, 79.2–89.8 (84.1 0.4); bill, 47–54 other pairs ( Johnsgard 1965a). O gives louder Ϯ Ϯ (50.0 0.3); tarsus, 30.3–37.5 (35.1 0.2). O repeated series of purrr calls during pre-laying and ϭ Ϯ (n 47) tail, 48–56 (52.0 0.3); wing, 184–205 early laying when disturbed by potential mammalian Ϯ Ϯ (195.3 0.6); keel, 76.4–88.3 (82.4 0.4); bill, predator (dog, fox); these calls generally given while Ϯ Ϯ 46–54 (49.7 0.2); tarsus, 32.0–36.8 (34.3 0.2). ‘tolling’ to predator (i.e. swimming close with head Weight data from winter (Louisiana), spring (Illinois, and neck extended maximally upwards) or rarely Minnesota), and fall migration (Minnesota), and while circling in flight around predator. southern breeding area (Manitoba); see Austin et al. (1998); o (n ϭ 1718) 546–1156 (maxima: fall staging Range and status [Oct, n ϭ 38] 959.0 Ϯ 17.8; minima: breeding season Breeds in open boreal forest and forest tundra of [May–Jul, n ϭ 40] 721.3 Ϯ 11.3 and winter [ Jan, Alaska east to Québec, and south in parkland and n ϭ 28] 721.4 Ϯ 8.8), O (n ϭ 1252) 517–1037 (max- prairie regions of eastern Oregon, Idaho, north Mon- ima: fall staging [Oct, n ϭ 36] 868.1 Ϯ 16.6; minima: tana, North and east South Dakota, and northwest spring staging [Mar, n ϭ 22] 647.5 Ϯ 16.1). Minnesota. Breeding-pair densities in central Canada highest in prairie parkland (north-central Alberta and Field characters southwest Manitoba), and lowest in southeast Alberta Small-bodied (380–430 mm long) diving duck dif- prairie grassland and boreal forest (Vermeer 1972). ficult to distinguish in field from larger Greater One of most common breeding wildfowl in boreal Scaup. o has purplish gloss on head and higher pro- forest of interior Alaska,Yukon, and Northwest Terri- file in comparison to greenish gloss and low, tories (Trauger 1971, Nudds and Cole 1991). Breed- rounded head profile of Greater Scaup o. Nail at tip ing-pair survey in May (Smith 1995) records largest of upper mandible noticeably and proportionately percentage of breeding scaup (Greater and Lesser smaller in Lesser Scaup; most readily observed in combined), on average, in Boreal Forest Region of field in o. In flight, white wing stripe of Greater Alaska and Canada (68%); smaller percentages Scaup typically extends from secondaries onto inner recorded in Prairie-Parklands of US and Canada 6 primaries, whereas white typically extends only (25%) and Tundra Region of Alaska (7%). Winters across secondaries and cuts off sharply at primaries primarily along Louisiana (Harmon 1962) and of Lesser Scaup. OO cannot easily be separated at Florida Gulf Coasts (Chamberlain 1960), Lake Okee- distance except by wing pattern. chobee, Florida (Turnbull et al. 1986), and Pacific and Ring-necked Duck readily distinguished from Gulf Coasts of Mexico, specifically coastal lagoons of Lesser Scaup by peaked head profile, white ring at Tamaulipas and Veracruz and Campeche and Yucatan base of bill, and grey wing stripe; o has dark back, and (Saunders and Saunders 1981, Baldassarre et al. 1989). Ducks_Vol-II-PartIIb.qxd 12/22/2004 5:28 PM Page 681 Lesser Scaup Aythya affinis 681 Largest percentages of wintering scaup recorded, on 1923, Stewart 1975), Minnesota (Roberts 1932) average, in Mississippi (42%) and Atlantic flyways and in Manitoba (Hochbaum 1944). Numbers (41%); smaller percentages in Pacific (10%) and Cen- using migration routes in river valleys of Illinois, tral flyways (7%) (Austin et al. 1998).Also common in Indiana, and on Mississippi River declined (Bellrose Pacific Northwest, upper midwest, and upper Atlantic et al. 1979, Mumford and Keller 1984, Korschgen coasts of US. Regular winter visitors farther south 1989). Continental population of Lesser and than other Aythya, to Central and South America and Greater Scaup combined (hereafter referred to sim- Caribbean (Botero and Rusch 1988); also occurs in ply as scaup), estimated from May Breeding Survey Hawaii and other Caribbean and Pacific islands. (Smith 1995), averaged 5 512 445 Ϯ 147 090 during Occasionally reported in Greenland (Bent 1923), 1955–95, with high of 7 996 967 in 1972 and low of Britain (Holian and Forley 1992), and on Canary 4 080 149 in 1993. Lesser Scaup estimated to com- Islands and The Netherlands; presently, 16 confirmed prise 89% of combined continental population of observations in western Palearctic (Clarke et al.
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