The Condor97:233-255 0 The Ccaper OrnithologicalSociety 1995

PHYLOGENY AND EVOLUTIONARY ECOLOGY OF MODERN SEADUCKS (ANATIDAE: MERGINI)l

BRADLEY C. LIVEZEY Section of Birds, CarnegieMuseum of Natural History, 4400 ForbesAvenue, Pittsburgh,PA 15213-4080

Abstract. Phylogenetic relationships of modem seaducks(Me&i) were investigated using a cladistic analysis of 137 morphological characters.The analysis produced a single tree (consistencyindex = 0.692, excludingautapomorphies) with complete resolutionof the relationshipsamong the 25 taxa recognized. Phylogeneticinferences include: (1) the eiders (Polystictaand Somateria) constitutea monophyletic group and are the sister-groupof other Mergini; (2) the remaining generic groups of Mergini, sequencedin order of increasingly close relationship, are Histrionicus,Melanitta + Camptorhynchus,Clangula, Bucephala + Mergellus.Lophodytes, and Mergus;(3) Somateria is monophyletic with S. jischerithe sister- group of its congeners;(4) the black scoters(Melanitta nigra-group)are the sister-groupof other scoters;(5) the Bufflehead (Bucephalaalbeola) is the sister-groupof the goldeneyes (B. clangufaand B. islandica);and (6) relationshipsamong mergansersare as presentedby Livezey (1989). Bootstrappingrevealed that the placement of the Smew as the sister-group of the goldeneyesis only weakly supported,and ancillary analysesrevealed that this place- ment is only one step shorter than its reduction to a trichotomy with the goldeneyesand mergansers(including Lophodytes).A phylogenetic classification of modem seaducksis presented. The Harlequin Duck (H. histrionicus),Long-tailed Duck (Ctangtda hyemalis), and Steller’s Eider (Polystictastellerz) are highly autapomorphic. Evolutionary patterns of selectedecomorphological characteristics-including body mass, sexual size dimorphism, clutch size, relative clutch mass, nest site, diet, diving method, formation of creches,and biogeography-are examined with respectto the phylogenetichypothesis. Key words: Anatidae; biogeography;comparative ecology; Mergini; morphology:phylog- eny; plumage; seaducks;waterfowl.

INTRODUCTION Systematists generally have agreed upon the Seaducks (Anatidae: Mergini) comprise a mono- composition of the group (Delacour and Mayr phyletic group of diving ducks largely limited in 1945; Boetticher 1942, 1952; Johnsgard 1961a, distribution to the northern hemisphere (Livezey 196 lb; Livezey 1986). Exceptions to this con- 1986). All but one species of Mergini spend at sensus were the failure to segregate the Mergini least part of the year on saltwater (Phillips 1925, from other diving ducks (Salvadori 1895; Phil- 1926; Delacour 1959; Johnsgard 1978), and the lips 1925, 1926; Peters 193 1) and the tribal sep- group is perhaps best known for the conspicuous, aration of the eiders from other Mergini (Hum- large, wintering flocks of several species of sea- phrey 1955, 1958a; Delacour 1959; Cramp and duck in Europe and North America. Two species Simmons 1977). Earlier morphological studies of Mergini have become extinct during historical provide differing, fragmentary, and often phe- times, the Labrador Duck (Camptorhynchus la- netic assessments of phylogeny within the tribe bradorius) and Auckland Islands Merganser (Delacour and Mayr 1945; Verheyen 1953; De- (h4ergu.saustralis), and several other species have lacour 1959; Johnsgard 1961a-1961c, 1964, undergone significant declines (Ring 198 1, Col- 1965, 1978, 1979; Woolfenden 1961). Livezey lar et al. 1992, Wilson Ornithological Society (1986) presented a genus-level phylogenetic anal- Resolutions Committee 1993). Fossil specimens ysis of modern Anseriformes based largely on of Mergini are mostly of Pleistocene age or youn- osteological comparisons, but species-level anal- ger (Brodkorb 1964, Howard 1964), although yses were not attempted. Livezey (1989) pre- fossils from as early as the Miocene have been sented a preliminary, species-level phylogenetic assigned to the tribe (Alvarez and Olson 1978). analysis of the mergansers using morphological characters. Molecular studies of the phylogeny of seaducks 1&Rived 28 April 1994.Accepted 13 October 1994. have been similarly limited. Jacob and Glaser

W31 234 BRADLEY C. LIVEZEY

(1975) and Jacob (1982) found that composition learctic M. nigra and Nearctic A4. americana. of integumental lipids confirmed a moderate dis- Similarly, two specieswere recognizedwithin the tance between the Common Eider (Somateria White-winged Scoter complex (Melanitta fusca- mollissima) and several other genera of Mergini. gp.)- Palearctic M. fusca and largely Nearctic M. Brush (1976) found a clear distinction between deglandi (including stejnegeri). the eiders and other Mergini using feather pro- teins, but was unable to make any finer resolu- SPECIMENS AND MATERIAL EXAMINED tions within the tribe. Patton and Avise (1985), With the exception of the extinct Labrador Duck, using electrophoresisof 13 proteins, reported a for which only a few appendicular elements were moderately large genetic distance between two available for study (Humphrey and Butsch 1958, speciesof Bucephala and the two other Mergini Zusi and Bentz 1978), skeletal specimens of all sampled (Melanitta and Clangula). Recent com- speciesof Mergini were examined for this anal- parisons of Anseriformes using DNA hybridiza- ysis. Many of the osteological characters used tion included only a single representative of the here were adapted from the ordinal analysis by Mergini (Melanitta) and therefore provided no Livezey (1986) a number of which were illus- insights into relationships within the tribe (Sibley trated by Shufeldt (1888) Schioler (1926), Wool- and Ahlquist 1990, Sibley and Monroe 1990). fenden (196 l), and Mijller (1969a, 1969b). Os- Similarly, comparisons using DNA hybridiza- teological nomenclature follows Baumel(l979) tion by Madsen et al. (1988) included only one as revised by Baumel and Witmer (1993). Tra- speciesof Mergini, the Hooded Merganser (Lo- cheae of males of all speciesbut the Labrador phodytes cucullatus). Duck and Brazilian Merganser (Mergus octose- This paper presentsa phylogenetic analysis of taceus) also were studied directly; a few char- modern Mergini using charactersof the skeleton, actersof the former were taken from nineteenth- trachea, natal plumage, and definitive plumages. century descriptions (see Humphrey and Butsch An exposition of the phylogenetic hypothesis is 1958) and characters of the latter were coded followed by a comparative analysis of selected using illustrations preparedby Humphrey (1955). characteristics of life history and biogeography Additional information on tracheal anatomy was based on the proposed phylogeny, and a phylo- taken from earlier studies (Latham 1798; Schiol- genetic classification is proposed. er 1926; Beard 1951; Humphrey 1955, 1958a; Johnsgard 196 1b, 1962; Humphrey and Clark MATERIALS AND METHODS 1964). Natal plumages were compared using study TAXONOMY skins of downy young for all speciesexcept the For purposes of this analysis, I recognized 25 Labrador Duck (for which even historical de- species-leveltaxa in the Mergini, which followed scriptions are not available) and the Brazilian conventional taxonomy (e.g., Johnsgard 1979) Merganser (codings for which were based on il- with three exceptions.These 25 operational units lustrations and descriptions in Delacour 1959 were the result of merging, for purposesof anal- and photographsin Bartmann 1988). Character- ysis, subspecieswithin polytypic speciesthat were istics of natal plumages also were confirmed us- identical for all characterscoded. These practical ing the descriptions and illustrations given by delimitations are broadly consistent with those Schieler (1926) Phillips (1925, 1926) Delacour prescribed by application of the phylogenetic (1959, 1964), Palmer (1976) and Nelson (1993). speciesconcept (Cracraft 1983, 1988; McKitrick Several of the plumage characters described by and Zink 1988). The Common Eider complex Livezey (1989) for natal and adult Mergus were (Somateria mollissima-gp.) was partitioned into excluded or modified to permit consistent, more four operational units: (1) mollissima of north- clearly defined states for coding throughout the western Europe, including comparatively small tribe. Characters of definitive plumages of sea- faeroeensis and provisionally islandica; (2) bo- ducks were defined through comparison of series realis of the arctic North Atlantic; (3) dresseri of of study skins of both sexesof each taxon, with Atlantic North America, including sedentaria; anatomical details (especiallycolors of soft parts) and (4) v-nigrum of the North Pacific. The Black confirmed through published descriptions of Scoter complex (Melanitta nigra-gp.) was divid- states in live or freshly collected birds (Dwight ed into two allopatric hemispheric forms-Pa- 19 14; Miller 19 16, 1926; Taverner 19 19; Schiol- PHYLOGENY OF MODERN SEADUCKS 235 er 1926; Kagelmann 195 1; Delacour 1959; Par- body mass of females. “Relative clutch mass” tridge 1956; Humphrey and Butsch 1958; Johns- was defined as the product of mean clutch size gard 1960a, 1978; Palmer 1976; Lucas 1979; and mean egg mass divided by the mean body Madge and Bum 1988; Gamer 1989; Livezey mass of adult females. Data on body mass were 1989). not available for the Labrador Duck, Auckland Outgroups were selectedon the basis of inter- Islands Merganser, or Brazilian Merganser; es- generic relationships inferred by Livezey (1986, timates of body massfor the last two specieswere 199 1) and included several species of Anatini taken from Livezey (1989). Such attributes were (sensu Livezey 1991; e.g., Cairina moschata, difficult to assign to one of two classesin some Mareca americana, Anas platyrhynchos),as well species,e.g., preferred nest site being “ground” as basal Oxyurini (e.g., Heteronetta atricapilla) versus “cavity” for the Harlequin Duck or fre- and Aythyini (e.g., Marmaronetta, Netta). Po- quency of nest parasitism in several species. larities of each character, based on distributions Therefore in these cases codings represent the of states among outgroups, were used to con- “typical” or modal state for each species. struct a “hypothetical ancestor” for rooting the tree(s). Relationships among outgroups remain ANALYSIS OF CHARACTERS poorly resolved (Livezey 1986, 199 l), therefore A total of 137 morphological characters were the method of “successiveoutgroups” could not identified that defined or varied within the Mer- be employed (Maddison et al. 1984). Study skins gini: 20 skeletal characters (17 modified from of adults, and samplesof skeletons,tracheae, and those of Livezey 1986), eight tracheal characters, downy young were used to establish character 17 charactersof natal plumage, and 92 characters polarities. of the plumage and soft parts ofadults (Appendix A number of generalized physical and func- 1). Each character comprised a primitive (ple- tional attributes vary among the Mergini in ways siomorphic) state and one or more derived (apo- that defied subdivision into discrete, homolo- morphic) states. All speciesof Mergini (the in- gous character states. For example, an increase group) were coded for each character, specimens in body mass in one lineage might result from permitting; species for which a character state enlargement of the pelvic musculature whereas could not be ascertainedwere assigneda missing- an equal increasein massin another lineage might datum code for that character. These character- reflect a generalized increase in bulk throughout state codes compose a 25 x 137 data matrix the body. Consequently, such variables were not (Appendix 2). Characters having more than one included as charactersin phylogenetic inference, derived state were considered unordered unless but instead were mapped a posteriori onto a tree a logical, consistent ordination by count, degree, inferred using other data (Appendix 1). None of or relative extent wasevident. Charactersin which these mapped attributes are known for the Lab- the derived state(s) were hypothesized to occur rador Duck, and many also remain undeter- in terminal lineages (autapomorphies) were in- mined for the Auckland Islands and Chinese cluded in the analysis because of the pervasive Mergansers.These ancillary data- including body influence such differenceshave had on tradition- mass, clutch size, egg size, nesting habits, diet, al classification. Moreover, inclusion of auta- and diving behavior-were taken from the lit- pomorphies confirms monophyly of terminal erature (Townsend 1909; Kelso 1922; Brooks taxa, permits estimates of evolutionary diver- 1945; Humphrey 1957, 1958b; Delacour 1959; gence, and explicitly accounts for phenetic dif- Schonwetter 196 1; Weller 1964a-1964d; Kear ferences among specieswithin the phylogenetic 1970; Raikow 1973; Bellrose 1976; Palmer 1976; tree. The consistency indices for all characters Cramp and Simmons 1977; Snell 1985; Eadie et were compared to assessthe phylogenetic utility al. 1988; Madge and Bum 1988; Rohwer 1988; of characters used in this analysis and in those Kehoe 1989; Livezey 1989; Rohwer and Free- of other tribes of Anseriformes (Livezey 199 1, man 1989; McNeil et al. 1992; Dunning 1993). unpubl. manuscripts). Mean body massesof specieswere estimated by the unweighted mean of the mean masses for DERIVATION GF TREES adults of the two sexesseparately. “Sexual size The fundamentals of phylogenetic analysis are dimorphism” was measured by the ratio of the described by Wiley (198 l), and similar analyses mean body mass of males divided by the mean of morphological data of Anseriformes were re- 236 BRADLEY C. LIVEZEY ported by Livezey (1986, 1989, 199 1). Trees were seaducks.Within the latter, the Harlequin Duck constructed using the phylogenetic software (Histrionicus) is the sister-groupof the remaining PAUP 3.1 (Swofford 1993); supplementary to- genera. Two major clades are defined within the pological analyses, a posteriori character map- genera of Mergini exclusive of the eiders and the pings, and printing of trees were performed on Harlequin Duck: (1) a clade in which the Lab- MacClade 3.0 1 (Maddison and Maddison 1992). rador Duck is the sister-groupof the scoters(Me- Both programs were implemented on a Macin- lanitta); and (2) a clade in which the Long-tailed tosh Quadra 800. I used heuristic algorithms Duck (Clangula) is the sister-group of the gol- (global branch swapping) to find the shortest deneyes (Bucephala), Smew (Mergellus), and tree(s), with MAXTREES set to 1,000 and the mergansers(Lophodytes and Mergus). MULPARS options in effect. Results were un- Steller’s Eider (Polysticta) was found to be the changed if the “random” sequence option for sister-group of the greater eiders (Somateria). addition of taxa was used instead of the default Within the latter, the Spectacled Eider (S. ji- option of “simple” addition. The character-state scheri) is the sister-group of the Ring Eider (S. optimization used was accelerated transforma- spectabilis)and the Common Eider complex (S. tion (ACCTRAN); employment of delayed mollissima-gp.). The mollissima complex is re- transformation (DELTRAN) did not affect the solved, in order of increasingly close relation- solution set. Bootstrappingof characterswas used ship, as the Pacific Eider (v-nigrum), Northern to assessthe relative stability of the resultant Eider (borealis), Canada Eider (dresseri)and Eu- branch patterns (Felsenstein 1985). This proce- ropean Eider (mollissima). Within the scoter dure-using heuristic methods, simple addition clade, the black scoters(A4. nigra and M. amer- of taxa, five trees held at each step, the MUL- icana) composethe sister-groupof the other sco- PARS option in effect, and trees held in memory ters; in the latter group, the Surf Scoter (M. per- (MAXTREES) of l,OOO-was used to generate spicillata) and the sister-speciesof white-winged 100 topological replications. Stability of branch- scoters(M. fusca and M. deglandi). This analysis es within the final tree was summarized by a 50% resolves the Smew to be the sister-group of the majority-rule consensustree of these 100 repli- goldeneyes;within the latter, the Bufflehead (B. cates.A strict interpretation of the resultant per- albeola) is the sister-group of the typical golden- centagesas statistical confidencelevels is not rec- eyes (B. clangula and B. islandica). Among the ommended, given the sampling assumptions mergansers,the Hooded Merganser (Lophodytes) required for such inference (Sanderson 1989). is the sister-group of other mergansers (Fig. 1). Within Mergus, a basal grade of the southem- PHYLOGENETIC CLASSIFICATION hemispheric species(A4. australis and M. octo- The resultant phylogenetic tree(s) formed the ba- setaceus)subtends a terminal clade in which the sis for a Linnean classification that maximally Common Merganser (M. merganser)is the sister- reflectsthe relationships inferred for the ingroup. group of the Red-breasted (M. serrator) and Chi- Unconventional taxonomic ranks (subtribes, su- nese Mergansers (A& squamatus). pergenera, and subgenera) were based on senior taxa of appropriate rank, in part based on the BRANCH LENGTHS AND STABILITY classificationsof Boetticher (1942, 1952) and the Stability of topology.One measure of supporting synonymies of Phillips (1925, 1926), Brodkorb evidence for each grouping is the number of syn- (1964), and Wolters (1976). apomorphies that define its basal stem (Fig. 1). RESULTS Monophyly of the tribe is supported by 13 syn- apomorphies, ofwhich 11 are unambiguous (i.e., PHYLOGENETIC TREE only one distribution of states permitted in the A single most-parsimonious tree was found (Fig. shortesttopology) and seven had unit consisten- 1). The tree was completely dichotomous, had a cy (CI = 1.0). Comparatively great support is length of 223, a consistencyindex (excluding un- given to the goldeneye-Smew-merganser clade informative characters)of 0.692, a retention in- (17 synapomorphies, 9 unambiguous) and So- dex of 0.894, and a resealed consistency index materia (13, lo), whereas only three character of 0.68 1. The eiders (Polysticta and Somateria) changes(all unambiguous) unite the Long-tailed were found to be monophyletic and these two Duck with the goldeneye-merganserclade. genera constitute the sister-group of all other The percentageof bootstrappedreplications of PHYLOGENY OF MODERN SEADUCKS 237 238 BRADLEY C. LIVEZEY the tree that retain a given branch offers an al- nounced autapomorphic divergence (i.e., char- ternative assessmentof topological stability (Fig. acter changesin terminal lineages),much of which 2). All branches in the final tree (Fig. 1) except involved unique aspectsof plumage patterns of the one uniting the Smew with the goldeneyes adults, and has tended to obscure their phylo- were preserved in a majority of the replicate to- genetic relationships when classifiedby phenetic pologies. Other branches varied in the percent- criteria. These divergent speciesare the Harle- agesof the topologiesin which they were retained quin Duck (11 autapomorphies, 7 unique for the (Fig. 2). Nine branches were preserved in over entire tribe), Long-tailed Duck (10, 7) Steller’s 90% of the replications, including those uniting: Eider (8, 5) Labrador Duck (8, 5), and Smew (8, (1) the eiders (Polystictaand Somateria); (2) the 3). Several of these terminal character changes genus Somateria; (3) the three subgroupswithin are not unique within the tribe and hence are of the scoters;and (4) the goldeneyes, Smew, and lower consistency,and in several of the foregoing mergansers. Comparatively weak support was species (especially the Harlequin Duck, Long- indicated for several other branches, including tailed Duck, and Smew) contribute to the insta- those defining: (1) the members of the Common bility of their placements in the tree. Eider complex (6 1% of replications);(2) the Long- CONSISTENCY OF CHARACTERS tailed Duck with the goldeneye-Smew-mergan- ser clade (58%); (3) the Mergini exclusive of the The four major charactergroups had similar av- eiders (65%); and (4) the Mergini exclusive ofthe erage consistency indices (CI): skeletal (0.87 to- eiders and Harlequin Duck (68%). Instability tal, 0.86 excluding unique autapomorphies), tra- within the Common Eider complex partly re- cheal (0.88,0.88), natal (0.79,0.75), and definitive flects the (modal) distribution of the black gular integument (0.89, 0.80). Although a majority of chevron (character 62) within the group; the po- charactersin each character set had consistency larity of this character in the shortest tree (Fig. indices of 1.0, there were charactersin each set 1) indicates that its infrequent appearancein So- showing one or more reversals or convergences. materia exclusiveof spectabilisand v- nigrum may Skeletal charactershaving comparatively low CIs be atavistic. The bootstrapped percentagesand involved the processussupraorbitalis (character counts of synapomorphies produced somewhat 1) and the foramen pneumaticurn stemi (char- different assessmentsof support for several other acter 5). Two charactersof the trachea-relative branches in the tree, in part because several of cranial prominence of the bulla syringealis(char- the included synapomorphies were of low con- acter 23) and presence of a bulbus trachealis sistency. For example, support for the branches (character 27)-also had low CIs. Three char- within the scoters(five synapomorphieseach, 93- actersof the natal plumage had exceptionally low 99% of replicates) contrasts with that for the CIs: presence of pale dorsal spotting (character branch uniting the Smew with the goldeneyes 30) presenceof a dark pectoral band (character (five synapomorphies, < 50% of replicates). 3 l), and ventral ground color (character 34). Fi- Monophyly of speciesand autapomorphic di- nally, a small minority of the characters of the vergence.Four terminal branches lacked auta- definitive integument had low consistencies,with pomorphies (Fig. l), therefore monophyly of the convergencesplaying a slightly larger role than correspondingtaxa was not demonstrated. These reversals in the added evolutionary steps. The taxa comprise two members of the Somateria latter included ground color of the bill (character mollissima complex (borealisand v-nigrum), and 48) blackish lateral barring (character8 l), ground the nominate forms of the white-winged and black color of lesserdorsal wing coverts (character85), scotercomplexes (Melanitta.fusca and A4. n&-a). and color of axillaries (character 88). These zero-length terminal branches do not in- dicate that the affected taxa should be merged ECOMORPHOLOGICAL COROLLARIES with their sister-species,because the taxa are dis- Body mass. Body mass and several related at- tinguishable from all others by combinations of tributes showed strong phylogenetic patterns charactersin the tree. However, further character among the Mergini (Fig. 3). There is a strong analysis is needed to determine whether these trend toward increased mass in the eiders (es- taxa are natural groups or define paraphyletic or pecially Somateria), with lesser trends toward polyphyletic groups. increased bulk in the scoters(especially M. fusca Several species were characterized by pro- and h4. deglandi) and within the mergansers(a PHYLOGENY OF MODERN SEADUCKS 239

P. stelleri S. mollissima

96 S. dresseri S. borealis S. v-nigrum S. spectabilis S. fischeri H. histrionicus C. labradorius M. fusca 65 L M. deglandi M. perspicillata c M. nigra 66 1 M. americana C. hyemalis B. albeola B. clangula B. islandica M. albellus L. cucullatus M. australis M. octosetaceus M. serrator M. squamatus M. merganser Ancestor FIGURE 2. Fifty-percent majority-role consensustree of 100 bootstrappedreplications of the shortestphy- logenetictree ofthe Mergini (Fig. 1). Percentagesofreplications in which eachbranch was conservedare indicated. local extreme being attained in Mergus mergan- two southern-hemisphere mergansers (not fig- ser). Sexual size dimorphism (Fig. 3) also showed ured, see Appendices 1, 2). very strong phylogenetic patterning in the Mer- Reproductive parameters. Mean egg mass gini, but was not associated with patterns in mean closely followed interspecific patterns in body body mass (Fig. 3). Independent increases in sex- mass. Phylogenetic patterns in clutch size, how- ual size dimorphism (Fig. 3) are indicated in the ever, were complex and showed negligible cor- Harlequin Duck and the white-winged scoter respondence with trends in body mass. The tree complex, and a strong trend toward increased indicates that the tribe underwent an initial mod- dimorphism is evident among the goldeneyes, est decrease in clutch size, followed by a further Smew, and the mergansers (the highest value for decrease in Somateria and subsequent increases the tribe being in the goldeneyes). Sexual di- in the white-winged scoters and independently chromatism is primitive for the tribe, but evi- in the goldeneyes and mergansers (Fig. 3). Rel- dently underwent independent reversals in the ative clutch mass, perhaps the best single indi- 240 BRADLEY C. LIVEZEY

I Sexual Dimorphism

FIGURE 3. Mappings of selectedcharacteristics on phylogeny of the Mergini: mean body mass, sexual size dimorphism, mean clutch size, and relative clutch mass. States are indicated by shading patterns on branches (seeadjacent keys). See Appendix 1 for characterdescriptions (attributes A, B, D, and I, respectively),Appendix 2 for data matrix. PHYLOGENY OF MODERN SEADUCKS 241

Clutch Size a b

FIGURE 3. Continued. 242 BRADLEY C. LIVEZEY cator of relative reproductive investment prior a Linnean classification including the following to hatching, is comparatively high in the Mergini classificatory points (Appendix 3): (1) subtribal generally, but evidently underwent a significant separation of the eiders from other seaducks;and decline in Somateria and independent increases (2) three supergenerawithin the latter subtribe. in the goldeneyes and the Hooded Merganser The position of the Smew remains only margin- (Fig. 3). Age of sexual maturity is two or more ally supported,although the preferred hypothesis years in the Mergini, apparently a derived con- is a sister-group status with the goldeneyes(Fig. dition shared by all members of the tribe (not 1); accordingly, I retain the taxon Mergellus as a figured, see Appendices 1, 2). monotypic genus. Recognition of the following Primary selection of terrestrial nest sites is taxa at specieslevel is recommended (see Ap- primitive in the Mergini, characterizing all but pendix 3 for subspecificassignments): Pacific Ei- the goldeneyes,Smew, and mergansers;the latter der (Somateria v-nigrum); White-winged Scoter share a derived preference for nest cavities. A (Melanitta deglandi);and American Black Scoter pronounced preference for semicolonial nesting (M americana). The isolation of the Pacific Ei- is shared by Somateria, as is the frequent for- der presumably was associatedwith divergence mation of creches. Intraspecific nest parasitism in a glacial littoral refugium (Rand 1948, Ploeger occurs in all Mergini at least infrequently, but 1968). The other three taxa in the Somateria available data mapped on the phylogeny of the mollissima complex analyzed here will require tribe indicates that significant increases in fre- further character analysis throughout their re- quency have evolved in three groups indepen- spective distributional ranges(including a quan- dently: the Common Eider complex, the golden- titative reassessmentof the bill characterscoded eyes, and the mergansers. Interspecific nest here) before formal consideration of speciessta- parasitism is less well documented among the tus is warranted. Preliminary study of the fossil Mergini, but thesedata indicate that increasesin genus Chendytes indicates that these flightless this behavior have evolved in the two large gol- ducks of the Pacific coastof North America were deneyes (Bucephala clangula and B. islandica) most closely related to the eiders (Livezey 1993). and independently in the Hooded Merganser Comparison with other authorities. The order (Appendices 1, 2). of genera proposed in the classic taxonomic ar- Habitat, locomotion, and diet. Although most rangements by Delacour and Mayr (1945) agrees speciesof Mergini occur at times on both fresh with that inferred here except that: (1) Steller’s and salt water, a preference for one or the other Eider was included within Somateria; (2) the feeding habitat generally characterizeseach spe- Harlequin Duck was placed after the Labrador cies, at least during nesting and brood-rearing. Duck and scoters instead of immediately after The presumed primitive preference is for fresh- the eiders; and (3) the Smew was placed in Mer- water, a condition retained by most members of gus as its first member. The sequence used by the tribe (not figured, see Appendices 1, 2). In- Delacour (1959) was identical except that the dependent shifts to approximately equal use of eiders were segregatedin a separate tribe (So- the two habitats are hypothesized for the white- materiini) and separatedin tribal sequencefrom winged scotersand the Long-tailed Duck, and a other seaducksby the pochards (Aythyini) and shift to coastal breeding areas is evident within “perching ducks” (Cairinini). Johnsgard(1960a) the eiders. Method of diving, which involves largely concurred with the arrangement by De- strokesof both wings and feet in dabbling ducks lacour (1959), except that he recommended: (1) and most Mergini, evidently underwent a spe- that the eiders be included with other seaducks; cialization to feet-only diving in the ancestor of (2) that Somateria precedePolysticta; (3) that the the goldeneyes, Smew, and mergansers.For the Labrador Duck immediately follow the eiders; mergansers and the Smew, this change in loco- and (4) that the Long-tailed Duck precede the motor method evidently was coincident with a scoters. shift to piscivory (Appendices 1, 2). Johnsgard(196 1a: 82) depicted a tree of “evo- lutionary relationships” in the Mergini based DISCUSSION largely on behavioral data. It differed from the PHYLOGENETIC RELATIONSHIPS AND present hypothesis (Fig. 1) in several ways: (1) CLASSIFICATION Steller’s Eider was shown as the sister-group of Natural class#icationof Mergini. The phyloge- the Mergini exclusive of Somateria; (2) the Lab- netic hypothesisproposed here is consistent with rador Duck was tentatively placed between the PHYLOGENY OF MODERN SEADUCKS 243 eiders and the Harlequin Duck; (3) the Long- (including Lophodytes) by Livezey (1986, de- tailed Duck was considered to be less closely picted as the former in figs. 1 and 5); in the cur- related to the goldeneyes and mergansers than rent analysis a sister-relationship between the the scoters;(4) the Smew was considered the sis- Smew and the goldeneyesis weakly supported as ter-group of the mergansers exclusive of the the most parsimonious hypothesis (Figs. 1, 2). Hooded Merganser; and (5) the Common and Relationships inferred here (Fig. 1) among the Chinese Mergansers were considered sister-spe- mergansers (Lophodytesand Mergus) are iden- cies, with the Auckland Islands Merganser ten- tical to those presented in an earlier analysis tatively placed as their sister-group. Johnsgard (Livezey 1989). (196 lc, 1964) provided additional arguments in Additional equally parsimonious topologiesfor support of the taxonomic positions of the eiders the Mergini have been discovered through sub- and Hooded Merganser. Taxonomic sequences sequent manipulations of the data set compiled used subsequently by Johnsgard (1978, 1979) by Livezey (1986) using improved versions of were identical with his earlier (1961a) arrange- PAUP (J. Harshman, pers. comm.). These alter- ment, except that Johnsgard (1979) listed the native arrangements primarily differ in (1) the Smew before the Hooded Merganser. depiction of the eiders, Harlequin Duck, and Manipulation of branches revealed that the Labrador Duck as monophyletic and/or (2) the hypothesis of paraphyly of the eiders shown by insertion of the monophyletic stiff-tailed ducks Johnsgard(196 1a) involved an additional seven (Oxyurini) as the sister-group of the Mergini ex- stepsin the hypothesis.Similarly, the alternative clusive of the mergansersor as the sister-group placement of the Long-tailed Duck depicted by of the mergansers,Smew, and goldeneyes.All of Johnsgard(196 1a) required two additional steps these alternatives are precluded by the enlarged than the phylogenetic hypothesis proposed hem data set analyzed in the present study. For ex- (Fig. 1). The tentative placement of the Labrador ample, the presence of the lobed hallux alone Duck proposedby Johnsgard( 196 1a) added four excludesthe basal member of the Oxyurini (Het- more steps to the hypothesis. Movement of the eronetta) from inclusion among the Me&i, and Smew to the position of the sister-group of Lo- any of several new charactersof the trachea, natal phodytes and Mergus entailed only one addi- plumage, or definitive plumage precludesthe di- tional step in the tree, whereasmaking the Smew vision of the Mergini or the partitioning of the the sister-group of the mergansers exclusive of clade comprising the goldeneyes, Smew, and Lophodytesnecessitates an additional five steps. mergansers(Fig. 1). Finally, the topology depicted by Johnsgard (1961a) for the Common, Chinese, and Auck- EVOLUTIONARY TRENDS land Islands mergansersrequired an additional The Mergini shareseveral life-historical and eco- eight stepsin the phylogeny. logical characters,including diving habit and pri- Comparison with generic placements of Liv- mary reliance on animal prey (Weller 1964a); ezey (1986). A phylogeny presentedin an earlier moderately heavy wing-loadings and rapid flight genus-level analysis of Anseriformes (Livezey (Raikow 1973, Livezey 1993) age of sexual ma- 1986: figs. 1, 5) differed from the present hy- turity of two or more years (Weller 1964b, Kear pothesis (Fig. 1) on three points. First, Livezey 1970) and predominantly diurnal activity pat- (1986) found that Steller’s Eider and other eiders terns (McNeil et al. 1992). Attributes showing (Somateria) were paraphyletic to other Mergini, the clearestpatterns among seaducksare (seeAp- whereas in the present analysis the eiders are pendices 1, 2; not figured): primary preference found to be monophyletic. Second,the Labrador for nest site (CI of character mapped onto tree a Duck was considered to be the sister-group to posteriori, 1.O), frequency of semicolonial nesting the Mergini exclusive of eidersand the Harlequin (1 .O), and diving method (1 .O). Several figured Duck by Livezey (1986) whereas the Labrador attributes (Fig. 3) (variation in clutch size [CI = Duck is hypothesized to be the sister-group of OSO], relative clutch mass [OSO], and sexual size the scotersin the presentanalysis. The placement dimorphism [OS]) as well as frequency of inter- of the Labrador Duck must be viewed with cau- specific nest parasitism (0.50; not figured) indi- tion, however, in light of the missing character cate moderate phylogenetic conservatism. Two states for this species(Appendix 2). Third, the other attributes having moderate phylogenetic Smew was hypothesized to be either the sister- constraint, sexual dichromatism (0.5) and mi- group to the goldeneyes or to the mergansers gratory habit (0.5), had coincident, paraphyletic 244 BRADLEY C. LIVEZEY reversalsin the two southern hemisphereMergus Scott and Clutton-Brock 1989). Increased clutch (not figured; see Appendices 1, 2). Body mass size in cavity-nesting birds is generally inter- (Fig. 3) and the closely covarying egg mass (Ap- preted as a responseto reduced predation (Mar- pendices 1,2) differed greatly among species,but tin 1992) but this hypothesisis not without con- this variation showedrelatively low phylogenetic troversy (Martin 1993). The frequency of creche conservatism (CI = 0.30 and 0.31, respectively). formation among Mergini is less intuitive, Comparatively low phylogenetic patterning is wherein relatively high frequency of creches evident (Appendices 1, 2; not figured) in pre- characterizeboth Somateria and the ecologically ferred aquatic habitat during nesting (0.40) and divergent clade comprising the Long-tailed Duck, relative frequency ofintraspecific nest parasitism goldeneyes,Smew, and mergansers(Appendices (0.33) and formation of creches(0.20). 1, 2). The occurrence of crechesand nest para- The phylogenetic patterning of body mass sitism, at least infrequently, in most Mergini is among Mergini (Fig. 3) defies easy evolutionary consistent with the association between K-type explanation. For example, although the derived life histories and brood amalgamation among massiveness of Somateria presumably contrib- Anatidae (Eadie et al. 1988) and the especially utes to easeof deep diving for benthic prey (Liv- high frequency of nest parasitism in the golden- ezey 1993) the absenceof increasedsize in other eyes and mergansers reflects a general increase genera having similar feeding and nesting habits in this parameter among cavity-nesting water- (e.g., Harlequin Duck, scoters,Long-tailed Duck) fowl (Rohwer and Freeman 1989). These repro- remains problematic. Whatever the selectiverea- ductive characteristics, combined with eco- sons for increased body size in Somateria, the morphological specialization for piscivory change is most parsimoniously interpreted as a (Woolfenden 196 1, Hoerschelmann 197 1, Liv- single homologous event in the common ances- ezey 1986) make the mergansersamong the most tor of the genus. Mean wing-loadings (g of body specialized of ducks. The phylogenetic patterns mass divided by cm2 of wing area) tabulated by in these parameters, however, indicate that at Livezey (1993) closely mirror these patterns in least some of this commonality is explainable by body mass. Interspecific patterns of clutch size phylogeny, and the derived conditions should of Anseriformes, hypothesized by Lack (1967, not be assumed to have arisen in each species 1968) to be largely a reflection ofenergy available independently. to females for egg production, are far from un- derstood (Rohwer 1988). A derived reduction in BEHAVIORAL EVOLUTION AND clutch size in Somateria (Fig. 3) is established HYBRIDIZATION beyond question, however, and together with in- Courtshipdisplays. Although the subject of com- creasedbody mass in the genus manifests a sub- paratively intense study in the wild and captivity stantial decreasein relative investment in eggs (Delacour 1959; Johnsgard1960a, 1960b, 196 1a, (Fig. 3). 1961c, 1964,1965; Cramp and Simmons 1977), At the opposite extreme are the cavity-nesting published accountsof courtship displays of Mer- goldeneyes,Smew, and mergansers(exclusive of gini do not permit the confident definition of the aberrant southern speciesof Mergus), where- displays of known homology and the determi- in small to medium body mass is associatedwith nation of statesfor a sufficient number of species large clutch sizes,relatively massive eggproduc- for formal phylogenetic analysis. Especially tion, and great sexual size dimorphism. Extremes problematic is the inadequate information avail- of relative clutch mass are attained by the Buf- able for two especially important genera of Mer- flehead and the Hooded Merganser (Fig. 3), gini, Harlequin Duck and Long-tailed Duck and extremes of sexual size dimorphism char- (Johnsgard 1960a), and no data whatsoever are acterize the goldeneyes (Fig. 3). These findings available for the Labrador Duck or Auckland confirm the earlier generalizations that cavity- Islands Merganser. Moreover, the diversity of nesting waterfowl, as well as species that have displays observed in the Mergini renders es- short-term pair bonds and low paternal invest- pecially difficult the determination of homolo- ment in young, tend to lay large clutches and gies, even among cl,oselyrelated genera (Johns- show atypically great size dimorphism (Sigur- gard 1963). Ethological inventories for the Mer- jonsdottir 198 1, Livezey and Humphrey 1984, gini(Johnsgard 1960a, 1961a, 1961c, 1962,1964, PHYLOGENY OF MODERN SEADUCKS 245

1965), however, permit two probable tribal syn- gansersis consistent with either view. However, apomorphies to be tentatively identified in the if fertile hybrids between eiders and Harlequin context of the present phylogenetic hypothesis Ducks were common, a phylogenetic interpre- (Fig. 1): precopulatory “upwards-stretch” by tation based on the presentedtree (Fig. 1) would males and precopulatory preening. Several other infer that primitive interspecific infertility sim- displays show variation among the Mergini and ply was retained (i.e., is symplesiomorphic) in therefore may provide additional insights into the segment of the paraphyletic grade including evolution within the tribe, including (Johnsgard these two genera. 1960a): precopulatory drinking by males, cop- ulatory wing-flicks, postcopulatory “rotations,” BIOGEOGRAPHY and postcopulatory “steaming.” General patterns. With currently available data, Interspecific hybridization. Hybridization a northern-hemisphere origin of the Mergini is among speciesof Mergini is rare, compared to an unavoidable inference (Howard 1964, Weller other tribes of Anatinae, but a diversity of hybrid 1964d). All Mergini but two members of the combinations of speciesand genera in the tribe most-derived clades in the tribe are limited in has been documented, including interspecifichy- distribution to the northern hemisphere, and bridization between congeners of all polytypic breeding by many of these is largely limited to genera, hybridization between members of dif- the Holarctic. Holarctic distributions of genera ferent genera of Mergini, and hybridization be- and subgenera, within which species occupy tween some Mergini and members of other tribes largely or completely allopatric subregions, is a of Anatidae (Ball 1934, Gray 1958, Johnsgard pattern repeated in Somateria (especially the S. 196Oc,Weller 1964c, Schererand H&berg 1982). mollissima complex), Melanitta fusca-gp., Me- Available compilations suggestthat Bucephala, lanitta nigra-gp., and Bucephala; this strongly Mergellus, Lophodytes,and Mergus are the gen- suggestsspeciation stemming from relatively re- era of Mergini most frequently involved in in- cent vicariance events. The distributional pat- tergeneric hybridization (Ball 1934, Gray 1958, terns of a number of seaducks(Polysticta stelleri, Johnsgard 1960~). Inter-tribal hybridization by Somateria (m.) v-nigrum, Somateria jischeri, Mergini most frequently involved pairings with Histrionicus histrionicus, Bucephala islandica, dabbling ducks (Anatini) or pochards(Aythyini) and Mergus squamatus) indicate the historical (Johnsgard 1960~). importance of the Pacific basin and adjacent con- Frequency of interspecific hybridization tra- tinental areas for speciation within the Mergini. ditionally has been considered an index to phy- The California distribution of the fossil seaducks logenetic relationships among Anseriformes, and of the genus Chendytesunderscores the diversity relatively high frequencieshave been interpreted of Mergini in the Pacific region (Livezey 1993). as the absence or failure of selectively advanta- Two of these largely Pacific species,Harlequin geous, often behaviorally based mechanisms of Duck and Barrow’s Goldeneye, also have lesser species discrimination and reproductive isola- populations in another apparent historical re- tion (Sibley 1957, Johnsgard 1963). An alter- fugium, the northern Atlantic. The Atlantic re- native, phylogenetically oriented view holds that gion also includes the former distributional range interspecific hybridization simply reflectsthe re- of the extinct Labrador Duck, as well as several tention of primitive reproductive compatibility of the most distinguishable populations of the S. among species, and therefore is not a reliable mollissima complex. Both the Pacific and Atlan- index of relationship; presumptions concerning tic refugia were probably isolated during north- selection for “isolating mechanisms” are irrele- em glaciations (Rand 1948, Ploeger 1968). vant to the issue and remain poorly reasoned Southern-hemisphere mergansers. The most (Livezey 199 1). It is unlikely that frequencies of intriguing biogeographical anomaly of the Mer- hybridization will provide compelling empirical gini concerns the distributions of the extinct weight to either perspective, and the choice of Auckland Islands and critically endangered Bra- interpretation is likely to remain one grounded zilian mergansers. Regardless of inferred phy- in systematic philosophy. For example, the rel- lygenetic position of these specieswithin Mergus atively high frequency of intergeneric hybridiza- (e.g., Johnsgard 1961a; Livezey 1989, present tion among the goldeneyes,Smew, and the mer- study), the isolated distributions and unique 246 BRADLEY C. LIVEZEY characteristicsof these two forms pose challeng- to two anonymous refereesfor constructivecriticisms ing evolutionary questions. In addition to their of the manuscript. widely separated,southern distributions, the two speciesare the only Mergini that are nonmigra- LITERATURE CITED ton, and lack sexual dichromatism. The Brazil- ALVAREZ.R., AND S. L. Orson. 1978. A new mer- ian Merganser (Bartmann 1988),,_ and possibly gamer from the Miocene of Virginia (Aves: Anat- also the Auckland Islands Merganser (Livezey idae). Proc. Biol. Sot. Washington 91522-532. BALL, S. C. 1934. Hybrid ducks, including descrip- 1989) differ(ed) from other Mergini in having tions of two crossesof Bucephalaand Lophodytes. protracted pair bonds. Both species probably Peabody Mus. Natur. Hist. Bull. 3: l-26. shared a specialization for rivet-me habitat (Liv- B~-~MANN, W. 1988. New observationson the Bra- ezey 1989). The absenceof sexual dichromatism zilian Merganser. Wildfowl 39:7-14. BAUMEL,J. J. 1979. Osteologia, p. 53-122. In J. J. (Appendices 1,2; not figured) is not homologous Baumel. A. S. Kina. A. M. Lucas. J. E. Breazile. in the two species,however, evidently being pae- and H. E. 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The evolutionary and taxonomic MILLER, W. DEW. 1916. The classification of the significance of sexual dimorphism and hybridiza- scoters. Auk 33:278-281. tion in birds. Condor 59: 166-I 9 1. MILLER, W. DEW. 1926. Structural variations in the SIBLEY, C. G., AND J. E. AHLQUIST. 1990. Phylogeny scoters. Am. Mus. Novit. 243:1-5. and classification of birds: a study in molecular MUELLER, W. 1969a. Vergleichend-morphologische evolution. Yale Univ. Press, New Haven, CT. Untersuchungen an Schldeln hiickertragender SIBLEY, C. G., AND B. L. MONROE, JR. 1990. Distri- Anatiden mit einem Beitrag zur Mechanik des An- bution and taxonomy of birds of the world. Yale atidenschadels II. Gegenbaurs Morphol. Jahrb. Univ. Press, New Haven, CT. 115:161-200. SIGURJ~NSD&~~IR, H. 198 1. The evolution of sexual MUELLER, W. 1969b. Vergleichend-morphologische size dimorphism in gamebirds, waterfowl and rap- Untersuchungen an Schldeln hiickertragender tors. Omis Stand. 12:249-260. Anatiden mit einem Beitrag zur Mechanik des An- SNELL, R. R. 1985. Underwater flight of Long-tailed atidensch%delsI. Gegenbaurs Morphol. Jahrb. 115: Duck (Oldsquaw) Clangula hyemalis. Ibis 127~267. 32-69. SWOFFORD,D. L. 1993. PAUP: phylogenetic analysis NELSON, C. J. 1993. The downy waterfowl of North using parsimony. Version 3.1. Smithsonian Inst. America. Delta Station Press, Deerfield, IL. Lab. Mol. Syst., Washington, DC. PALMER, R. S. 1976. Handbook of North American TAVERNER, P. A. 19 19. An important distinction be- birds. Vol. 3. Yale Univ. Press, New Haven, CT. tween our two goldeneyes (Clang&a clangula PARTRIDGE. W. H. 1956. Notes on the Brazilian Mer- americana and Clanmla islandical. Can. Field- ganser in Argentina. Auk 73:473488. Nat. 33:57-58. - PA~ON, J. C., AND J. C. AVISE. 1985. Evolutionary TOWNSEND, C. W. 1909. The use of the wings and genetics of birds IV: rates of protein divergence in feet bv diving birds. Auk 26:234-248. waterfowl (Anatidae). Genetica 68: 129-143. VERHEYE~, R. 1953. Bijdrage tot de osteologie en de PETERS,J. L. 193 1. Check-list of birds of the world. systematiek der Anseriformes. Gerfaut 43:373- Vol. 1. Harvard Univ. Press, Cambridge, MA. 456. PHILLIPS, J. C. 1925. A natural history of the ducks. WELLER, M. W. 1964a. General habits, p. 15-34. In Vol. 3. Houghton Mifflin, Boston, MA. J. Delacour [ed.], The waterfowl of the world. Vol. PHILLIPS, J. C. 1926. A natural history of the ducks. 4. Country Life, London. Vol. 4. Houghton Mifflin, Boston, MA. WELLER, M. W. 1964b. The reproductive cycle, p. PHYLOGENY OF MODERN SEADUCKS 249

35-79. In J. Delacour [ed.], The waterfowl of the 7. Sternum, carina stemi, margo ventralis (lateral world. Vol. 4. Country Life, London. perspective): (a) convex throughout; (b) essentially WELLER,M. W. 1964~. Ecology, p. 80-107. In J. straight (Livezey 1986: character 80). CI = 1.00. Delacour led.], The waterfowl of the world. Vol. 8. Sternum, rostrum stemi, labrum dorsalis: (a) 4. Country Life, London. rounded notch, (b) rounded notch with small spina WELLER. M. W. 1964d. Distribution and soeciesre- intema medially (Livezey 1986: character 82). CI = lationships, p. 108-120. In J. Delacour ied.], The 1.oo. waterfowl of the world. Vol. 4. Country Life, Lon- 9. Sternum, corpus sterni, trabecula mediana, don. marked extension caudal to linea intermuscularisand WILEY, E. 0. 1981. Phylogenetics:the theory and processuscaudolateralis: (a) absent; (b) present (Liv- practice of phylogenetic systematics.J. Wiley & ezey 1986: character 83). CI = 1.00. Sons, New York. 10. Sternum, corpus stemi, caudal closure of inci- WILSON ORNITHOLOGICALSOCIETY RESOLUTIONS suramedialis, forming fenestramedialis: (a) absent;(b) COMMITTEE. 1993. Resolution on the Steller’s present (Livezey 1986: character 84). CI = 1.00. [and Spectacled]Eider. Wilson Bull. 105:719. 11. Humerus, extremitas proximalis humeri, fossa WOLTERS,H. E. 1976. Die Vogelarten der Erde. Part pneumotricipitalis,foramen pneumaticurn:(a) present, 2. Paul Parey, Hamburg and Berlin. fossalargely open; (b) absent, fossaentirely closed;(c) WOOLFENDEN,G. E. 1961. Postcranial osteologyof reduced to scattered foramina pneumatica in osseus the waterfowl. Florida State Mus. Bull. (Biol. Sci.) surface(Livezev 1986: character 28). CI = 0.67. 6:1-129. 12. Humerus, extremitas proximalis humeri, crista YARRELL,W. 1885. A history of British birds. Vol. bicipitalis, distal segment:(a) poorly developedor sim- 4. Van Voorst, London. ply shelf-like; (b) produced medially, enclosingelon- ZUSI, R. L., AND G. D. BENTZ. 1978. The appendic- gate sulcus,typically with translucentcranial wall (Liv- ular myology of the Labrador Duck (Cumpto- ezey 1986: character 30). CI = 1.00. rhynchuslubradorius). Condor 80:4074 18. 13. Carpometacarpus, extremitas proximalis car- pometacarpi,trochlea carpalis,labrum dorsalis,prom- inent swellingon distal terminus: (a) present;(b) absent APPENDIX 1 (Livezey 1986:character 37, descriptioncorrected with respectto labrum involved). CI = 0.50. CHARACTER DESCRIPTIONS 14. Carpometacarpus, corpus carpometacarpi, OS Characters analyzed as unordered unless marked by metacarpale majus, facies dorsalis, impressio m. ex- “0”; primitive states correspond to state “a” unless tensor metacarpiulnaris, position relative to synostosis another state is highlighted in boldface. CI = consis- metacarpalisproximalis: (a) opposite, at least in part; tency index. (b) completely distal (Livezey 1986: character 43, re- vised). CI = 1.00. SKELETON 15. Femur, extremitas proximalis femoris, trochan- Numbers of charactersbased on Livezey (1986) are ter femoris, cranial prominence relative to that of caput given in parentheses.Character 24 of Livezey (1986) femoris:(a) significantlygreater; (b) approximatelyequal has been determined to be unreliable and was miscod- (Livezey 1986: character 52). CI = 1.00. ed in the Mergini, and is deleted. Erratum of tree la- 16. Femur, corpus femoris, craniocaudalcurvature belling (not data analysis) in Livezey (1986: Fig. 5): (lateral perspective):(a) essentiallyabsent, straight;(b) basal character change“ 78a-c” should be “75a-c.” moderate; (c) pronounced, subangular(Livezey 1986: 1. Cranium, OSprefrontale, processussupraorbital- character 55). CI = 0.67. is: (a) small, straight,essentially coplanar with OSfron- 17. Femur, extremitas distalis femoris, fossapopli- tale, faciesdorsalis; (b) long, slender,dorsally directed, tea: (a) shallow; (b) deep (Livezey 1986: character56). often curved (Livezev 1986: character Il. revised). CI CI = 1.00. = 0.50. _ 18. Tibiotarsus, extremitas distalis tibiotarsi, con- 2. Cranium, OS frontale, dorsal inflation (Miiller dylus medialis, cranial prominencerelative to condylus 1969a):(a) absent;(b) present.CI = 1.OO. (See character lateralis: (a) distinctly greater;(b) approximately equal 47.) .I (Livezey 1986: character 64). CI = 1.00. 3. Maxilla, shape:(a) not markedly narrow, not spe- 19. Tibiotarsus, extremitas proximalis tibiotarsi, cialized for piscivory (Mergellus somewhat interme- cristacnemialis cranialis, continuation by distinct ridge diate); (b) narrow, specializedfor piscivory. CI = 1.00. on corpus tibiotarsi, facies cranialis to distal terminus 4. Cranium, OSprefrontale, processusorbitalis; dis- of crista fibularis: (a) absent;(b) present(Livezey 1986: tinct broadening,lateral convexity, distal rounding:(a) character 65). CI = 1.00. absent; (b) present. CI = 1.00. 20. Tarsometatarsus,extremitas distalis tarsomet- 5. Sternum, corpus stemi, facies visceralis stemi, atarsi, canalis interosseustendineus, lamina covering foramen pneumaticurn:(a) open, ovoid; (b) absent;(c) dorsal of two canaliculi: (a) intact, obscuring dorsal reduced, largely occluded by medial lamina (Livezey canaliculus in dorsal view; (b) largely incomplete or 1986: character 78, revised). CI = 0.40. absent,exposing dorsal canaliculus in dorsalview (Liv- 6. Sternum, rostrum stemi, spina extema: (a) long, ezey 1986: character 69). CI = 1.00. peg-like; (b) pair of points separatedby a shallow me- dial sulcus;(c) obsolete;(d) single,short, dorsoventrally TRACHEA (Fig. 4) compressed flange (Livezey 1986: character 79, re- 21. Syrinx, bulla syringealis (0): (a) present, large, vised). CI = 0.60. tympanum distinctly asymmetrical;(b) present, small, 250 BRADLEY C. LIVEZEY tympanum roughly symmetrical; (c) obsolete (Ring DEFINITIVE PLUMAGES AND 1989). CI = 1.00. SOFT PARTS 22. Syrinx, bulla syringealis,fenestrae: (a) absent; (b) present. CI = 1.00. Pertain to definitive alternate plumagesof males unless 23. Bulla syringealis, relative to cranial margin of indicated otherwise. fused portion of trachea: (a) left side not cranially 46. Iris color (especiallymales): (a) brown; (b) bright prominent; (b) left side cranially prominent. CI = 0.50. white; (c) yellow; (d) red. CI = 0.75. 24. Bulla syringealis:(a) not as follows; (b) cranially 47. Basal swelling of maxilla (also involves under- peaked, with two narrow arches enclosing three ling bone; Mijller 1969b): (a) absent; (b) present, pre- obliquely opposingfenestrae. CI = 1.OO. dominately dorsal; (c) present, predominately lateral. 25. Bulla laryngealis:(a) absent;(b) present (Yarrell CI = 1.00. (See character 2.) 1885, McLelland 1989); (x) not known (some type of 48. Bill, ground color: (a) gray; (b) yellow or orange. enlargement described inadequately for Cumptorhyn- CI = 0.33. thus). CI = 1.00. 49. Bill color, basal (partly seasonal)intensification 26. Bulbus trachealis, single, dorsoventrally com- of greenish-yellowcolor (where present)to orange-red: pressedand ovoid, composed of fused tracheal rings: (a) absent; (b) present, orange, especially males in (a) absent;(b) present(Yarrell 1885, McLelland 1989). breeding season(S. spectabilis comparatively reddish). Note. -Reported paired swellingsin Camptorhynchus, CI = 0.50. if accurate,not consideredhomologous. CI = 1.OO. 50. Bill color, contrastingyellow patches:(a) absent; 27. Bulbustrachealis, in which trachealrings are not (b) present, lateral; (c) present, medial. CI = 1.OO. truly fused: (a) absent; (b) present. CI = 0.50. 51. Bill color, females: (a) lacking yellow patches; 28. Bulla syringealis,right lobe (if present):(a) rel- (b) with yellow patches.CI = 1.00. atively small; (h) markedly enlarged. CI = 1.OO. 52. Hallux, lobation: (a) absent; (b) present. CI = 1.oo. NATAL PLUMAGE (Fig. 5) 53. Foot color: (a) gray; (b) greenish, with variable 29. Pale (bully) facial stripes: (a) absent; (b) present, yellow tones; (c) orange;(d).pink. CI = 0.60. narrow; (c) present, broad. CI = 1.00. 54. Conspicuouslyelongate maxillary cornices: (a) 30. Pale dorsal (scapularand rump) spots:(a) pres- absent; (b) present (evident only in female of S. spec- ent (variably reduced in Mergellus); (b) absent. CI = tabilis). CI = 1.00. 0.33. 55. Elongate maxillary cornices (if present) (0): (a) 3 1. Contrasting, dark breast band: (a) absent; (b) acuminate:(b) not distinctly broad, moderately round- present. CI = 0.33. ed, (c) comparatively broad, rounded. CI = l:OO. 32. Breast band (if present): (a) uniform or contin- 56. Black, lateroventral border ofbill: (a) absent;(b) uously graded, (b) distinctly two-parted, darker cra- present. CI = 1.00. nially, paler caudally. CI = 1.OO. 57. Basal feathering on lateral surfacesof maxilla 33. White suborbitalspot: (a) absent;(b) present.CI (evident also in natals)(0): (a) absent;(b) present,mod- = 1.00. erate; (c) present, extensive; (d) present, extreme, 34. Ventrum: (a) whitish; (b) dusky. CI = 0.33. reaching narial aperture. CI = 0.50. 35. Narrow, whitish loral stripe: (a) absent;(b) typ- 58. Facial pattern (females): (a) not as follows; (b) ical. CI = 1.00. dark with separate,pale antorbital and auricular spots; 36. Tawny wash on cheeks, breast: (a) absent; (b) (c) dark with sharply defined, pale cheek extending present. CI = 1.00. dorsally to just below orbit. CI = 1.00. 37. B&y malar stripe: (a) absent; (b) present. CI = 59. Medially divided, black crown: (a) absent; (b) 1.00. present. CI = 1.00. 38. Pale femoral patches:(a) absentor indistinct; (b) 60. Black border anterior and ventral to orbit: (a) deep, often bounded ventrally with dark, forming third absent; (b) present. CI = 1.00. pair of dorsal spots. CI = 0.50. 6 1. P&orbital, narrow black border enclosingsig- 39. Contrasting pale cheeks:(a) absent; (b) present. nificant area of white: (a) absent; present. CI = 1.OO. CI = 1.00. 62. Black chevron on throat (0): (a) absent;(b) pres- 40. Color of head:(a) brown or gray, lackingreddish ent, rare; (c) present, typical. Note.-See Humphrey tones; (b) reddish brown. CI = 1.00. f1955) and Palmer (1976). CI = 0.67. 41. Dark, comparatively ventrally bowed cheek 63. ’ Suborbital green region: (a) absent; (b) present. stripe: (a) absent;(b) present(indistinct in Mergus aus- CI = 1.00. trulis). CI = 1.00. 64. White, crescent-shaped,orbital patches:(a) ab- 42. Narrow, white suborbital stripe, confined ven- sent; (b) present. CI = 1.00. trally by dark cheek stripe: (a) absent; (b) present. 65. Head plumage,blackish with iridescence:(a) ab- Note. -State in M. octosetaceus based on illustrations sent; (h) present, greenish; (c) present, bronze-green; in Partridge (1956) and Delacour (1959) although (d) present, purplish. CI = 0.60. presence not evident in photographs by Bartmann 66. Sharply defined, variably shaped, white antor- (1988). CI = 1.00. bital spots:(a) absent; (b) present. CI = 0.50. 43. Whitish antorbital spot: (a) absent; (b) present. 67. Nuchal crest: (a) absent; (b) present, uniformly CI = 0.50. long, continuously emergent from corona to occiput; 44. Pale alar stripe: (a) present;(b) absent.CI = 0.50. (c) present, essentiallyone-parted tuft from corona;(d) 45. Wing linings: (a) pale; (b) dark, with only a few present,shaggy, unevenly long, typically “two-parted.” scatteredpale feathers. CI = 1.OO. CI = 1.00. PHYLOGENY OF MODERN SEADUCKS 251

68. Nuchal region: (a) not green; (b) with restricted 89. Wing linings: (a) dark, or mottled with dark: (b) greennuchal prominence; (c) extensivelygreen; (d) light essentiallypure white. CI = 0.50. blue. CI = 1.00. 90. Outermost primary remiges: (a) not distinctly 69. Broad, complete white collar separatinglargely ematginate;(b) distinctlyemarginate, especially in adult

dark head from dark mantle: (a)_ I absent:I, (b) I_ mesent. CI males. Note.-See Dwight (1914). CI = 1.00. = 0.50. 9 1. Secondaryremiges (0): (a) dark or metallically 70. Narrow, dark nape stripe interruptingwhite neck toned; (b) blackish (medio)oroximallv. white (la- collar: (a) absent; (b) present. CI = 1.00. tero)di&lly; (c) entirely white. CI = 0.67: . 7 1. Upper back (mantle): (a) variably colored; (b) 92. Uppertail coverts (rump): (a) black; (b) gray or immaculately white. CI = 1.OO. brown. CI = 0.50. 72. White of mantle (if present), extending latero- 93. Undertail coverts (vent): (a) not uniformly col- caudally, producinglateral flank patches:(a) absent;(b) ored, typically mottled brown; (b) blackish; (c) essen- present. CI = 1.00. tially white. CI = 1.00. 73. Scapulars:(a) not conspicuouslyelongate, short- 94. Rectrices:(a) not elongate,pointed; (b) elongate, er than underlyingtertials; (b) greatly elongate,at least pointed. CI = 1.00. as long as tertialsyCI = 1.OO. 95. Dusky gray, spottedcranial border to white vent:

74. Tertials: (a) not as follows:I., (b) elonaate.1 I laterallv (a) absent; (b) present. CI = 0.50. curved. CI = l.bo. 96. Modal number of pairs of rectrices(0): (a) sev- 75. Scapulars,contrasting lateral black stripe:(a) ab- en: (b) e&t: (c) nine. CI = 0.67. sent; (b) present, variably extensive. CI = 1.00. 97. Head’ and mentum dark uniform brown, with 76. Scapulars,tertials, ground color: (a) variably dark sharp demarcation from paler color of upper breast brown, gray or black; (bywhite. CI = 0.50. (definitive females): (a) absent;(b) present. CI = 1.OO. 77. Chin, restricted white oatch (adult females):I (a)~I 98. Iridescent purple, white-striped scapulars:(a) ~ absent; (b) present. CI = 1.00. absent; (b) present. CI = 1.OO. 78. Paired, ventrallydiverging, black shoulderstripes 99. Distinct, black shoulder spots: (a) absent; (b) separatedby white: (a) absent; (b) present. CI = 0.50. present. CI = 1.00. 79. Breast, ground color: (a) dark brown; (b) white 100. Largelyrufous ventrum: (a) absent;(b) present. (bulIy in PoZysticta. ventrally restricted in Somateria CI = 1.00. fischeri. heavily barred in Mergus octosetaceus, sulfused 101. Purplish-black throat, collar: (a) absent; (b) with pale gray in M. australis); (c) black(ish);(d) slate- present. CI = 1.00. blue; (e) red. CI = 0.60. 80. Lower breast, sides, belly: (a) not jet black; (b) 102. Fine, sharply defined, black orbital rings or jet black, like vent. CI = 0.50. “spectacles”: (a) absent; (b) present. CI = 1.OO. 8 1. Sides and flanks, blackish barring or vermicu- 103. Large, red crista cornea frontalis (“frontal lations: (a) absent; (b) present, essentially linear; (c) shield”): (a) absent; (b) present. CI = 1.00. present, broad scalloping.CI = 0.40. 104. Narrow, elongate, black crown stripe: (a) ab- 82. Flanks, crus, and lower belly (females) (0): (a) sent; (b) present. CI = 1.00. lacking contrastingly dusky suffusion; (b) dusky suf- 105. Sharply defined, white, auricular spot: (a) ab- fusionpresent on cruralregion, but not extendingacross sent; (b) present. CI = 1.00. vent between thighs; (c) dusky suffusionon mural re- 106. Narrow, white stripes on sidesof neck: (a) ab- gion and extending between thighs forming trans-ab- sent; (b) present. CI = 1.00. dominal band. Note.-Codings for Mergus australis, 107. Pair of black-bordered, white stripeson shoul- M. octosetaceus difficult. CI = 1.OO. ders: (a) absent; (b) present. CI = 1.OO. 83. Typical contour feathers (females): (a) not as 108. Small, sharply defined, white flank spots: (a) follows; (b) brown with black, transversebars or horse- absent; (b) present. CI = 1.00. shoe-shapedmarks. CI = 1.00. 109. Contrastingly deep chestnut sides: (a) absent; 84. Predominatelyblackish body plumage,dorsally, (b) present. CI = 1.00. ventrally, and laterally (readily wearing to brown): (a) 110. Irregular, white preorbital and circular, white absent; (b) present. CI = 1.OO. postorbital spots (females): (a) absent; (b) present. CI 85. Lesser upper wing coverts, ground color: (a) = 1.00. variably dark throughout;(b) white throughout;(c) dark 111. Head and neck (exclusive of crown) white: (a) on leading edge, white behind. CI = 0.25. absent; (b) present. CI = 1.00. 86. Conspicuousblack bar acrosswhite dorsal wing 112. Narrow black crown patch, terminating at oc- region (formed by the exposure of comparatively ex- ciput: (a) absent; (b) present. CI = 1.00. tensive black proximal portions of greater secondary 113. Narrow, contrastinglyblack collar: (a) absent; coverts by overlying white or pale gray median sec- (b) present. CI = 1.00. ondary coverts): (a) absent; (b) present. CI = 1.OO. 114. Patch of distinctly stiffened feathers on cheek: 87. Metallic, contrastingly colored secondaryrem- (a) absent; (b) present. CI = 1.00. iges (wing speculum): (a) present, bordered caudally 115. Distinctly spatulatebill (both sexes):(a) absent; with white, in both sexes;(b) vestigial, caudally bor- (b) present. CI = 1.00. dered with white, in females, but absent in males; (c) 116. Yellow basal bill swelling (derived extension present,but not borderedcaudally with white, in males, of medial yellow patchof maxilla to includebasal knob): but absent in females; (d) absent in both sexes.CI = (a) absent; (b) present. CI = 1.00. 1.00. 117. Uniquely prominent basal bill swelling:(a) ab- 88. Axillaries: (a) dark brown; (b) white. CI = 0.25. sent; (b) present. CI = 1.00. 252 BRADLEY C. LIVEZEY

I CM

FIGURE 4. Osseustracheal and synringeal structuresof male Mergini, ventral views: A-Polysticta stelleri, bulla syringealis(USNM 224029); B-Somateriu (mollissima)dresseri, bulla syringealis(KUMNH 13336); C- Histrionicushistrionicus, bulla syringealis(KUMNH 605 14); D-Melanitta perspicillata,bulbus trachealisand bulla syringealis(KUMNH 3 1307); E-Melanitta (nigra) americana, tympanum syringealis(UMMZ 225 126); F- Clangula hyemalis, bulla syringealis (USNM 499413); G-Bucephalu clungzdu,bulla syringealis(FMNH 348957); H--Bucephak albeolu, bulla syringealis (UMMZ 198362); I-Mergellus albellus, bulla syringeahs (IJSNM 585082); J-Lophodytes cucullatus,bulla syringealis(KUMNH 13816); K-Mergus merganser,bulla s.kngealis (KUMNH 67638). PHYLOGENY OF MODERN SEADUCKS 253

I CM

FIGURE 5. Plumage patterns of natal Mergini, lateral views: A-Polysticta stelleri (USNM 121267); B- Somateria (mollissima) dresseri(FMNH 25861); C-Histrionicus histrionicus(USNM 79065); D-Melanitta Cfusca) deglandi (UMMZ 121344); E-Clangula hyemalis (USNM 88948); F-Bucephala clangula (FMNH 129623); G-Lophodytes cucuZIatus(USNM 82293); H--Merges serrator(USNM 203184). 254 BRADLEY C. LIVEZEY

118. Contrasting, white frons and nuchal patches: I. Sexual size dimorphism (ratio of mean male mass (a) absent; (b) present. Cl = 1.00. to mean female mass, g; 0): (a) < 1.15; (b) 1.15-l .25; 119. Laterally extensive, elaborately patterned (c) >1.25. maxillar plates: (a) absent; (b) present. Cl = 1.OO. J. Primary prey group: (a) invertebrates; (b) verte- 120. Scapulars black medially with tawny margins brates. ~o;plemental, males): (a) absent; (b) present. Cl = K. Diving method: (a) wing (at least at submergence) and feet; (b) feet only. 12 1. Head and neck entirely black except for white, L. Typical aquatic habitat during nesting (0): (a) tear-shaped orbital patch (supplemental, males): (a) ab- freshwater; (b) freshwater and saltwater; (c) saltwater. sent; (b) present. Cl = 1.00. M. Migration: (a) present; (b) absent. 122. Head and upper neck grayish white except for N. Formulation of creches: (a) infrequent; (b) com- black lower cheeks (alternate, males): (a) absent; (b) mon. present. Cl = 1.00. 0. Intraspecific nest parasitism: (a) infrequent; (b) 123. Scapulars uniformly pale, grayish white (alter- common. nate, males): (a) absent; (b) present. Cl = 1.OO. P. Interspecific nest parasitism: (a) infrequent; (b) 124. Greatly elongated medial rectrices (all defini- common. tive plumages, males): (a) absent; (b) present. Cl = 1.OO. 125. Subterminal pink region on maxilla (both sex- APPENDIX 2 es):(a) absent; (b) present. Cl = 1.00. CHARACTER-STATE MATRIX 126. Prominent, white auriculo-nuchal patches (males, reduced in females): (a) absent; (b) present. Cl This matrix of 137 morphological characters described = 1.00. in Appendix 1 is available from the author on request. 127. Second, more-caudal black bar in dorsal sec- The matrix will be supplied on diskette if a Macintosh- ondary coverts, caused by exposure of dark bases of format diskette is provided by the reader. secondary remiges by overlying greater secondary rem- iges (females): (a) absent; (b) present. Cl = 1.OO. APPENDIX 3 128. Sharp black shoulder marks, produced by cran- PHYLOGENETIC CLASSIFICATION ioventral extensions of dark mantle: (a) absent; (b) present. Cl = 1.00. Taxonomic ranks based on inferred phylogeny (Figs. 129. Head white except semicircular black orbital 1, 2), after the methods of Wiley (198 1). Phylogenetic patch and black stripe in ventral margin ofnuchal crest: species recognized within traditional species taxa retain (a) absent; (b) present. Cl = 1.00. a parenthetical abbreviation of the “superspecific” tax- 130. Crown, orbital area, and nape chestnut (fe- on, and other subspecific taxa included in each follow males): (a) absent; (b) present. Cl = 1.00. the binomen. Note that the sequence of three generic 131. Sharply contrasting white throat and lower groups Bucephala,Mergellus, and Lophodytes+ Mer- cheeks (females): (a) absent; (b) present. Cl = 1.OO. gas is indeterminate (i.e., the sequence should be an- 132. Contrasting, pale rufous sides: (a) absent; (b) notated sedismutabilis). present. Cl = l.OOT _ ORDER ANSERIFORMES (Wagler, 183 1). 133. Prominent, black-bordered, white nuchal crest: Suborder Anseres Wagler, 183 1. (a) absent; (b) present. Cl = 1.OO. Family Anatidae Vigors, 1825. 134. Ventrum densely barred with blackish (both Subfamily Anatinae Swainson, 1837. sexes): (a) absent: fb) oresent. Cl = 1.00. 135. Sharp‘ blackbaning’ on breast: (a) absent; (b) Tribe Mergini Delacour and Mayr, 1945.-Seaducks. present. Cl = 1.00. Subtribe Somatereae Boetticher, 1942.-Eiders. 136. Narrow white gular stripe from breast dorsally Genus PolystictaEyton, 1836. into green collar: (a) absent; (b) present. Cl = 1.OO. Polystictastelleri (Pallas, 1769).-Stellers’ 137. Complete, ’ broad, white collar: (a) absent; (b) Eider. oresent. Cl = 1.00. Genus Somateria Leach, 18 19. -Greater Ei- ders. ATTRIBUTES FOR MAPPING Subgenus Lampronetta Brand& 1847. (Primitive states are listed “a” unless given in bold.) Somateria jischeri (Brandt, 1847). -Spec- A. Mean body mass (unweighted mean of sexes, g; tacled Eider. 0): (a) ~700; (b) 700-1,100; (c) l,lOO-1,600; (d) 1,600- Subgenus Somateria Leach, 18 19. 2,100; (e) >2,100. Somateria spectabilis(Linnaeus, 1758).- B. Mean clutch size (0): (a) 4-6; (b) 6-9; (c) 9-11. King Eider. C. Egg mass (g, after Schiinwetter 196 1; 0): (a) ~60; Somateria(m.) v-nigrumGray, 1855.-Pa- (b) 60-70; (c) 70-80; (d) >80. cific Eider. D. Clutch mass relative to mean female body mass Somateria (m.) borealis(Brehm, 1824).- (0): (a) ~30%; (b) 3O-50%; (c) SO-70%; (d) 70-90%; Northern Eider. (e) >90%. Somateria(m.) dresseriSharpe, 187 1 (incl. E. Age at sexual maturity (yr): (a) one; (b) two. provisionally sedentaria Snyder, F. Primary nest site: (a) ground; (b) cavity. 1941).-Canada Eider. G. Semicoloniality: (a) absent; (b) typical. Somateria(m.) mollissima(Linnaeus, 1758) H. Sexual dichromatism: (a) present; (b) absent. (incl. small, insularfaeroeensis Brehm, PHYLOGENY OF MODERN SEADUCRS 255

183 1, and provisionally islandica Genus BucephalaBaird, 1858.-Goldeneyes. Brehm, 183I).-European Eider. SubgenusBucephala Baird, 1858. Subtribe Mergeae Boetticher, 1942.-Typical Sea- Bucephalaalbeola (Linnaeus, 1758).-Buf- ducks. behead. SupergenusHistrionicus Lesson, 1828. SubgenusGlaucionetta Stejneger, 1885. Genus HistrionicusLesson, 1828. Bucevhala clangula (Linnaeus, 1758).- Histrionicushistrionicus(Linnaeus, 1758).- Common Goldeneye. Harlequin Duck. Bucephafaislandicu (Gmelin, 1789).-Bar- SupergenusMelanitta Boie, 1822.-Scoters and row’s Goldeneye. Labrador Duck. Genus Mergellus Selby, 1840. Genus CamptorhynchusBonaparte, 1838. Mergellus albellus (Linnaeus, 1758).- Camptorhykhus labradorius (Gmelin, Smew. 1789).-Labrador Duck. Genus LophodytesReichenbach, 1853. Genus Melanitta Boie, 1822.-Scoters. Lophodytescucullatus (Linnaeus, 1758).- Subgenus Melanitta. -White-marked Sco- Hooded Merganser. ters. Genus Mergus Linnaeus, 1758.-Typical Mer- Melanitta perspicillata(Linnaeus, 1758).- Surf Scoter. Su~g~~~ Promergus Mathews and Iredale, Melanitta cf: ) fica (Linnaeus, 1758).- 1913. Velvet Scoter. Mergus australisHombron and Jacquinot, Melunittu cf:) degiandi(Bonaparte, 18 14). - 1841 _-Auckland Islands Merganser. White-winged Scoter (incl. stejnegeri SubgenusPrister Heine, 1890. Ridgway, 1887). Mergus octosetaceusVieillot, 1817.-Bra- Subgenus Oidemia Fleming, 1822.-Black zilian Merganser. Scoters. SubgenusMergus Linnaeus, 1758.-Greater Melanitta (n.) nigra (Linnaeus, 1758).- Mergansers. Eurasian Black Scoter. Mergusmerganser Linnaeus, 1758.-Com- Melanitta (n.) americana (Swainson and mon Merganser. Richardson, 183I).-American Black Mergus serrator Linnaeus, 1758.-Red- Scoter. breasted Merganser. SupergenusMergus. -Linnaeus, 1758.-Mergan- Mergus squamatusGould, 1864.-Chinese sersand allies. Merganser. Genus Clangula Leach, 1819. Clangula hyemalis (Linnaeus, 1758).- Long-tailed Duck.