Biological Science Report 

USGS/BRD/BSR- 2000-0002 
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Cover photo: U.S. Fish and Wildlife Service research staff banding American Black Ducks on the mid-Atlantic 

coast, Cape May County, New Jersey, January, 1977. Photo by Ronald E. Kirby, USGS. 

G) Printed on recycled stock 
Description and Identification of 

American Black Duck, Mallard, 

and Hybrid Wing Plumage 

Biological Science Report 

USGS/BRD/BSR-2000-0002 

March 2000 

by 

Ronald E. Kirby 

Austin Reed 

Pierre Dupuis 

Holliday H. Obrecht, III 

Walter J. Quist 

U.S. Geological Survey 

Biological Resources Division 

N orthem Prairie Wildlife Research Center 

Jamestown, North Dakota 
Suggested citation.· 

Kirby, R.E., A. Reed, P. Dupuis, H.H. Obrecht, III, and W. J. Quist. 2000. Description and identification of American 

Black Duck, Mallard, and hybrid wing plumage. U.S. Geological Survey, Biological Resources Division, Biological 

Science Report USGS/BRD/BSR-2000-0002. 26 pp. 
Contents 

Page 

Abstract ........................................................................................................................................................................ 1 

Resume (Abstract in French) ....................................................................................................................................... 2 

Introduction . . .... . . . . . . . . . . . . . ... . . . ... . . . . . . . . . .. . . . . .. . . . . . . . . .. . . . . . . ... . .... . . . . . .. . .. .. . . . . . . . . .. . .. .. . . . . . . . ... . . . ... . . . . . . . .. ... . . . . . . . . . ... . . . ... . . . . . . . .. . . . ... . . . 2 

Scope of the Problem.................................................................................................................................................. 3 

Methods ....................................................................................................................................................................... 4 

Plutnage Examination . ... .. . . . . . .. . . . . . . .. . . . . . . . . ... . . . . . . . .. . . . .. . . . . . . . .. ... . . . . . . . . .. . . . ... . . . . .... . . .. .. . . . . . . . . . . .. .. . . . . . . . . . .. . . . . .. . . . . . . . .. . . . .. . . . . . . . . 4 

Experimental Flock of Hybrids . . ... . . . . . . . . . .. . . . . . . . . .. . . .. . . . . . . . .. . .. . . . . . . . . . .. . . .. . . . . . . . . . . . ... . . . . . . . . . . .. . . .. . . . . . . .. . . . . .... . . . . . . .. . . . . .. . . . . . . . . . 4 

Results ........................................................................................................................................................................ 4 

Historical and Current Descriptions of Mallard and Black Duck Wing Plumages .. .. .... ... .... .. ................ .... . .. .. .. ..... 4 

Mallard ................................................................................................................................................................ 4 

Black Duck ..... . . . . . . . . . . . .. .. . . . .. . . . . . . . .... . . .. .. . . . . ... ... .. . . . . .. . . . .. . . . . . ... . . ... . . . . . . . . ... . .. . . . . . . . . .. .. . . .. .. . . . . .. . . .... . . . . . . . . . . ... . . . . . . . . . . .... . . .. . 5 

Underwing Plumage .. . . . ..... . . . . ..... . . .. ... . . . . . . . .... . . . . . .. . .... . . . . . .. . .. ... . . . . . . . . . .. . . .. . . . . . . . ... . . . .... . . . . . .. ..... . . . . . . . . .... . . . . . . . . . . . . ... . . .... . 5 

Species Descriptions and Characters of Study Skins and Wings .. .. .... .. .. .. .. ... .. .... .... .. . .. ...... .. .. . .. .. .... .. .... .. .. .... .. .... . .. 6 

Mallard Wings in Museums and Modem Parts Collections .. .. .. .. .. .. ... .. .. .... .. .... .. .. .. .. .... .. .. .. .. .. .. .. .. .. . .. .. .. .. .. ..... .. .. . 6 

Black Duck Wings in Museums and Modem Parts Collections .... ..... .. .. .... .. .... ... .. .. ...... . .. .. .. .... .. .... .. .. .... .. .... .. .. .. . 6 

A Revised Description of Mallard Wing Plumage.................................................................................................. 6 

A Revised Description of Black Duck Wing Plumage ... ... . . . . . . . .. . . . .. . . . . . . . . .. ... .. . . . . . . . . . . .. . . . .. . . . . ... . .. ... . . . . . . . . .. . .. . . . . . . . . .. .. . 6 

Independent Confirmation ofthe Revised Black Duck Wing Description ... .. . . . . . . . . . .. .. . . .. . . . . ..... ............ .. . ... . . . . . . .... 10 

Black Duck x Mallard Hybrid Wing Plumage ...................................................................................................... 10 

Hybrids Propagated at Jamestown..................................................................................................................... 10 

Sex Determination of Hybrid Wings ................................................................................................................. 10 

Discussion................................................................................................................................................................. 15 

Key for Identification of Hybrid Wings . . . . . . .. .. . . . . . . . .. . . ... . . . . . ... . .. .. . . . . . . . . .. . ........... ... . . .... . . . . . . .. . ............. .. .. ......... ..... .... 15 

Identification of Domestic Mallards . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . 15 

Limitations of the Wing Key . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . .. .. . . . . . . . 15 

What Proportion of the Hybrids in a Sample Can Be Identified? ... . . ..... . . . ... . . . ... .. . . . . . . . ... .. . . . . . . . . ..... ..... . . . . ...... ... .. . . . 17 

Reinterpretation of the 1977 U.S. Parts Collection Survey .................................................................................. 17 

Comparison with Another Quantitative Measure of Hybridization ...................................................................... 17 

The Need for Additional Research ........................................................................................................................... 18 

Acknowledgments . . ..... . . . . . . . . . . ... .. . . . . . . . . . . . ..... ... . . . .. . . .. . . . . . . . ............ ...... .. . . . . . . . . . . .............. ...... ... . . ........ .... . . . . . . . . .. ... . . . . . . . .... 19 

Literature Cited . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 

Appendix ................................................................................................................................................................... 23 

Tear-sheets for Dichotomous Key ............................................................................................................................ 27 

lll 
Figures 

Mtmber Page 

Photograph of a typical wing from an immature male Mallard illustrating the range 

of dorsal and ventral characters expected in wild forms ................................................................................ 7 

2 Dorsal and ventral photographs of a typical wing from an immature female Mallard 

illustrating the same features as in Figure 1 ................................................................................................... 8 

3 Dorsal and ventral photographs of a typical wing from a Black Duck illustrating 

characters expected in wild fonns .................................................................................................................. 9 

4 Dorsal and ventral photographs of a wing from an adult male hybrid resembling 

for the most part a Black Duck ...................................................................................................................... 11 

5 Dorsal and ventral photographs of a wing from an immature female hybrid resembling 

for the most part a Black Duck..................................................................................................................... 12 

6 Dorsal and ventral photographs of a wing from an adult female hybrid resembling 

for the most part a Mallard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 

7 Dorsal and ventral photographs of a wing from an immature female hybrid resembling 

for the most part a wing intermediate between Black Duck and Mallard . . . .. . . . . . .. . . . . . . . . . . . . . . . . .. ... . . . . . . . . . . .. . . . . . .. 14 

8 Frequency distribution of the width of white bars bounding the speculum on the 

wing dorsum of Black Ducks, Mallards, and hybrids from an experimental flock reared 

at Northem Prairie Wildlife Research Center. All measurements are compared 

with Mallard = 1 00%~ actual range in width 0-10 mm............. .. . . . . . . . . . . . . . . . . . .. . . . . . .. . . . . . . . . . . . . . . . . .. . .. . . . . . . . . . . .. . . . . . . . 18 

Table 

A dichotomous key for identification of wings from American Black Ducks, Mallards 

and hybrids between the two . . . .. . .. . . . . . . . . . . .. . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . ... .. . . . . . . . . . . . .. .. . . .. . . . . . ... . . .. .. . . . . . . . .. . ... . . . . . . . . . . .. .. . . . . 16 

IV 
Description and Identification 

of American Black Duck, Mallard, 

and Hybrid Wing Plumage 

By 

Ronald E. Kirby 

U.S. Geological Surve.F 

Northern Prairie Wildltfo Research Center 

Jamestmt'll, North Dakota, USA 58401 

Austin Reed and Pierre Dupuis 

Canadian Wtldltfo Service 

1141 Route de I 'Eglise 

Ste-Fo)~ Quebec, Canada G1V 4H5 

and 

Holliday H. Obrecht, liP and Walter J. Quisf 

U.S. Geological Sun/e_J,. 

Patuxent Wtldltfo Research Center 

Laurel Maryland, USA 20708 

Abstract: We developed a key to identify wings of hybrids between American Black Ducks (An as rubripes) and 

Mallards (A. pla(vrh;vnchos). Material for analysis included review of historical descriptions dating from the late 

1700's, older museum collections in Europe and North America, wings collected from hunters in North America 

and Great Britain, birds banded in Canada and the United States, and a flock of propagated hybrids. All first filial 

generation (F 1

) American Black Duck x Mallard hybrids were identified correctly with the key. A lower proportion of other hybrid cohorts (i.e., backcrosses ofF 1 to parental forms (P 1 ), and second and third filial generations 

(F2, F3

, etc.) were identified. We successfully identified a larger portion of male than female hybrids for all 

hybrid progeny cohorts examined except F1

• The new key identified 2.37 times more hybrids in the 1977 U.S. 

Fish and Wildlife Service Parts Collection Survey (annual determination of the species, age, and sex composition of the waterfowl harvest using detached wings contributed by hunters) than were identified by standard 

techniques. The proportion of American Black Duck x Mallard hybrids to the American Black Duck parental 

population (the ratio: hybrids/[hybrids +American Black Ducks]) may therefore be closer to 0.132 than 0.056, 

the historically reported value. The hybrid key is suggested for use from North Carolina north in the Atlantic 

Flyway and Arkansas and Tennessee north in the Mississippi Flyway (areas where other members of the Mallard 

group will not confound assessment). We provide suggestions for further research that would assist identification of wings in parts collection surveys and permit estimation of the proportional representation of Mallard 

genes in the American Black Duck gene pool. 

Key Words: American Black Duck, Anas platpizynchos, Anas rubripes, domestic Mallard, hybridization, Mallard, museum, parts collection surveys, plumage, waterfowl, wings. 

1

Current address: U.S. Fish and Wildlife Service, Patuxent Research Refuge, 12100 Beech Forest Road, Laurel, Maryland 

20708-4036 

2

Current Address: U.S. Fish and Wildlife Service, Northeast Regional Office, 300 Westgate Center Drive, Hadley, Massachusetts 

01035 
2 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR-2000-0002 

Resume: Une clef pour identifier les ailes d'hybrides entre le Canard noir (Anas rubripes) et le Canard colvert 

(A. platyrhynchos) a ete developpee a partir de documentations diverses. Celles-ci etaient composees de descriptions datant de la fin du XVIII" siecle jusqu'a nos jours, d'anciennes collections de specimens issues des 

musees europeens et nord-americains, d' ailes recoltees aupres de chasseurs d' Amerique duN ord et d' Angleterre, 

d'oiseaux captures a des fins de baguage au Canada et aux Etats-Unis, et d'individus d'un groupe captif dont la 

genealogie etait connue. Cette clef a permis d'identifier correctement tousles hybrides Canard noir x Canard 

col vert de la premiere generation (F 1 ). Une proportion plus faible des generations subsequentes d'hybrides (i.e. 

croisement F 1 x forme parentale, hybrides F, F3 , etc.) a ete correctement identifiee avec la clef, et dans ce cas, le 

taux de succes d'identification etait plus el~ve chez les males hybrides que chez les femelles. L'utilisation de 

cette meme clef pour identifier les ailes de la recolte de 1977 de 1' United States Fish and lfHdl(fo Sen ice a 

permis d'identifier 2,37 fois plus d'hybrides que les methodes traditionnelles utilisees jusque-la. Suite aces 

identifications, la proportion d'hybrides Canard noir X Canard colvert par rapport ala population parentale du 

Canard noir (le ratio: hybrides/[hybrides + Canard noir]) est evaluee a 0,132 plutot qu'a 0,056, la valeur 

rapportee historiquement. L'utilisation de cette clef est done recommandee pour identifier les ailes des canards 

provenant des regions s' etendant jusqu' au sud de la Caroline duN ord dans le corridor de migration de 1' Atlantique, 

etjusqu'au sud de l'Arkansas et du Tennessee dans le corridor de migration du Mississippi, excluant ainsi les 

regions plus meridionales ou d'autres especes apparentees au Canard colvert pourraient compromettre 

1 'identification. Des suggestions· sont egalement proposees quant au developpement de methodes destinees a 

faciliter !'identification des ailes envoyees par les chasseurs et pem1ettant !'estimation de la proportion des 

genes de Canard colvert dans le pool genetique du Canard noir. 

Introduction 

The American Black Duck (Anas rubripes) (hereafter 

Black Duck) is a priority concern of waterfowl managers 

as described in the North American Waterfowl Management Plan (Canadian Wildlife Service and U.S. Fish and 

Wildlife Service 1986) because its populations have 

declined. This decline has been attributed to loss and 

degradation of habitat, harvest by hunters, and competition and hybridization with Mallards (A. p!atyrhynchos), 

which are expanding their range eastward (Rogers and 

Patterson 1984; Ankney et al. 1987, 1988; Kirby 1988; 

Rusch et al. 1989). Relative numbers of the two species 

in many portions of the East have changed (Collins 

1974; Dennis et al. 1984; Ankney et al. 1987; D'Eon et 

al. 1995). Continued release of captive-reared Mallards 

and the establishment of resident, feral Mallard flocks 

have provided opportunity for increased interspecific 

matings between Black Ducks and Mallards. Some 

waterfowl ecologists believe that introgressive hybridization has been and will continue to have an increasingly detrimental influence on Black Ducks (Heusmann 

1974, 1988; Spencer 1980, 1986; Ankney et al.1987; 

Kirby 1988), but biologists differ on the consequences 

of hybridization for the Black Duck gene pool (Ankney 

et al. 1986, 1987, 1989; Ankney and Dennis 1988; Hepp 

et al. 1988; Conroy et al. 1989). Because ofthese 

disagreements, population monitoring schemes need 

estimates of year-specific incidence ofhybridization and 

the long-tenn trend in hybridization. 

Early attempts to assess the incidence and trend of 

hybridization between the two species with electrophoretic techniques failed except in identifying first filial 

generation (F1

) hybrids and the parental generation (P1

) 

(Morgan et al. 1976, 1978, 1984a, 1984b). Subsequent 

biochemical investigations (Patton and A vise 1983, 

1985; Oates et al. 1984; Ankney et al. 1986; Avise et al. 

1990) and phylogenetic (cladistic) analyses (Livezey 

1991 and review therein) confirmed that Black Ducks 

and Mallards are closely related but did not provide 

information useful in identifying hybrids. 

A true estimate of hybridization rate, that is, the 

proportion of mixed pair bonds formed in the wild or the 

actual numbers of hybrids hatching from mixed-species 

matings, has been obtained only in limited, accessible 

areas (e.g., Longcore et al. 1987; Sanderson 1993; 

D'Eon et al. 1994). No schemes to obtain such data on a 

large scale in the wild have been attempted. Instead, 
DESCRIPTION AND IDENTIFICATION OF WING PLUMAGE 3 

measures of interaction between Black Ducks and 

Mallards have been confined to documenting shifts in the 

breeding range (e.g., Collins 1974; Dennis and North 

1984a, 1984b; Dennis et al. 1984, 1989; Ross and 

Fillman 1990), examining changes in the relative 

abundance of the two species in annual Mid-winter 

Waterfowl Survey counts (Steiner 1984) or Christmas 

Bird Counts (Wing 1943; Johnsgard 1961; Johnsgard 

and DiSilvestro 1976), and calculating the fraction of the 

wings submitted to the annual U.S. Fish and Wildlife 

Service and Canadian Wildlife Service Parts Collection 

Surveys putatively identified as hybrids (Johnsgard 

1967; summaries in Carney et al. 1975, 1983). Only this 

last measure attempts to address frequency of hybridization per se in wild populations. 

Despite the limitations of the parts collection surveys 

(Martin and Carney 1977; Boyd and Finney 1978), they 

are valuable information tools for management (Boyd et 

al. 1974 ). It is the only technique currently capable of 

detecting changes in Black Duck x Mallard hybridization 

over the entire range of sympatry. In the early 1970's, the 

Canadian Wildlife Service (Quebec Region, Ste-Foy, 

Quebec) and two U.S. Fish and Wildlife Service (now 

U.S. Geological Survey) entities (Northern Prairie 

Wildlife Research Center, Jamestown, North Dakota, and 

Patuxent Wildlife Research Center, Laurel, Maryland) 

independently began studies to refine means of detecting 

Black Duck x Mallard hybrids. These efforts were 

combined in 1976. Between 1976 and 1983, field, laboratory, and museum studies were conducted. Since 1984, 

the techniques established were further evaluated in the 

field; oral presentations on the techniques also resulted 

in important feedback. In this paper, we present the sum 

of more than two decades of evaluation of the issue, 

provide an improved key for identification of Black 

Duck x Mallard hybrids, and reinterpret previously 

published data on Black Duck x Mallard hybridization. 

Scope of the Problem 

Standard keys used in North American parts collection 

surveys (Carney 1964, 1992) identify age and sex of 

waterfowl by species but not intergrades or aberrant 

forms. Consequently, identification of Black Duck x 

Mallard wings is subjective and inexact (Carney et al. 

1983:1 ). Historically, Mallard-like wings with unusually 

dark dorsal surfaces, overall dark wings with an anterior 

white border to the speculum, and wings with an 

indistinct white line anterior to the speculum all have 

been considered indicators of hybridization with Black 

Ducks. However, these traits have not been rigorously 

assessed as indicators of hybridization (He us mann 

1974). S.M. Carney (U.S. Fish and Wildlife Service, 

personal communication) described more recent techniques as "relatively standard throughout," even though 

specific criteria for identifying hybrids and captivereared(= hand-reared) and domestic-strain birds have 

not been published. Carney defined the criteria used by 

the mid-1980's for Black Duck x Mallard hybrids as 

follows: 

[In comparison with the typical Mallard 

wing]. .. good procedures for this type of identification are lacking. Birds intermediate in color 

between the two species are considered hybrids. 

These normally have a poorly defined white stripe 

anterior to the speculum .... Although we only look 

on the underwing of birds that are suspect, the 

presence of a few dark brown feathers usually 

causes us to consider the bird a hybrid. Birds 

considered to be "hand-reared" are those with extra 

white on the tertials, dark underwings, or odd 

proportions of length to width (a few of the latter 

are unusually large wings). Unfortunately, the 

major area for both crosses and "hand-reared" birds 

appears to be the same, i.e., southern New England 

to Virginia. 

Major difficulties in identifying wild Black Duck x 

Mallard hybrids arise from ( 1) the lack of obvious sexual 

dichromatism in the Black Duck; (2) the existence of a 

number of plumage characteristics, often referred to as 

inherent "Mallard" characteristics, in typical Black Duck 

plumage (Phillips 1912, 1915, 1921); (3) substantial 

plumage variation among individuals possibly related to 

nutrition and stress (cf. Kirby and Fredrickson 1990); ( 4) 

a rather broad range of "typical" plumage features in 

both species; (5) considerable geographic variation in 

plumage of both species; and (6) interbreeding of wild 

Black Ducks with released or otherwise feral Mallards 

throughout much of historic Black Duck breeding and 

wintering range. Further, uncertainty about what constitutes "typical" Black Duck plumage has stymied 

attempts to determine hybridization incidence (e.g., 

Heusmann 1974; Johnsgard and DiSilvestro 1976; 

Morgan et al. 1978, 1984b ), even though most investigators agree that plumage coloration per se (Bellrose 1976) 

or plumage coloration plus the "curly" tail feather 

character of male Mallards (Livezey 1991) can be used 

to distinguish the two species even in the absence of 

other useful morphometric variables ( cf. Hanson and 

Ankney 1994). The range ofvariation in Black Duck 

plumage has not been described and only limited 

descriptions of Black Duck x Mallard hybrid plumage 

are available (Dutcher 1889; Eaton 1903; Bigelow 1907; 

Phillips 1915, 1921; Kortright 1942). Palmer (1976:328) 

summarized what little is known of this variation: 

... the Black has considerable individual variation in 

characters of feathering, some geographical 
4 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR-2000-0002 

variations in these, some clinal variations in size 

(larger northward), and the effects of limited 

crossing with Mallard and perhaps Mottled Duck 

are somewhat obscured by imprecise knowledge of 

the full extent of variation in "pure" Black Ducks. 

Methods 

We reviewed historical (1758 -present) descriptions 

of Mallard and Black Duck wing plumage to establish 

standards for comparison. We confirmed species and 

hybrid characters through inspection of wings from 

Mallard populations that probably had little or no 

contact with Black Duck populations, including the 

collections of 11 museums (Smithsonian Museum of 

Natural History, Washington, D.C.; American Museum 

of Natural History, New York, New York; Academy of 

Natural Sciences, Philadelphia, Pennsylvania; Museum 

of Comparative Zoology, Harvard University, Cambridge, Massachusetts; Royal Museum ofNatural 

History, Toronto, Ontario; Museum of Natural History of 

Canada, Ottawa, Ontario; Wildfowl Trust, Slimbridge, 

Gloucestershire, England; Harrison Museum, Seven 

Oaks, Kent, England; British Museum, Tring, 

Hertfordshire, England; Royal Scottish Museum, 

Edinburgh, Scotland; and the Allison Collection, Loch 

Leven, Kinross, Scotland). We further evaluated species 

and hybrid characters in live-trapped birds from Thurso, 

Quebec (1974-76), New Jersey (1976-78), and Maine 

(1977-78) and parts collection survey receipts from three 

countries and a number of years (Canadian Parts 

Collection Surveys 1975-76, 1976-77, 1977-78, 1978-

79; U.S. Atlantic Flyway 1976-77, 1977-78, 1978-79; 

U.S. Pacific Flyway 1976-77; British Parts Collection 

Survey 1976-77). We also examined an experimental 

flock of 248 Black Duck x Mallard hybrids. Finally, we 

developed a key for identifying hybrid forms and 

reanalyzed Mallard-like and Black Duck-like wings 

obtained in the 1977 U. S. Parts Collection Survey. 

Plumage Examination 

We used a subsample of the live birds and wholebody study skins to compare plumage characters with 

published descriptions. For each bird, we initially sorted 

data for 42 individual feathers or feather tracts by size, 

shape, color, and internal patterns within feathers as part 

of an ongoing study in Canada (P. Dupuis, unpublished 

data). We compared areas of white on the wing dorsum 

to a Mallard standard (e.g., a male and female wing 

showing the characters illustrated in Carney 1992: Figs. 

3 and 4 ). We examined additional specimens for only 

wing characters, although other aspects of the plumage, 

if unusual, were noted qualitatively. We analyzed 

plumage criteria in the same fashion for the large 

numbers of wings obtained from the annual parts 

collection surveys. We also analyzed specimens of 

Mottled Ducks (A. fit!J ·igula) and Mexican Ducks (A. 

dia:a = dia::i group of A. platyrhynchos of American 

Ornithologists' Union 1998) whose ranges partially 

overlap those of Black Ducks and Mallards. In order to 

quantify the total range of variation in the collections, we 

likewise evaluated all specimens in the 11 museum 

collections that were identified in the catalogues or on 

the specimen labels as Anas spp. hybrids, domestic 

breeds, or unusual varieties. 

Experimental Flock of Hybrids 

In the early 1970's, F. B. Lee reared a captive flock of 

P1 Mallards from California and North Dakota and P1 

Black Ducks from New Brunswick (some hand-reared in 

North Dakota) at Northern Prairie Wildlife Research 

Center near Jamestown, North Dakota. In 1974-76, a 

breeding program was established to develop various 

hybrids from these parental forms. Following a series of 

related studies, the hybrid flock became available for our 

use in November, 197 6, when we examined them and 

compared them with wild birds shot by hunters and 

reported to the U.S. Parts Collection Survey. We made 

study skins of representative individuals and entered 

them into the collections of the Smithsonian Museum of 

Natural History. 

Results 

Historical and Current Descriptions of 

Mallard and Black Duck Wing Plumages 

Mallard 

First scientific descriptions of the Mallard (Latham 

1785; Pennant 1785) differed little from earlier nonscientific descriptions or subsequent scientific accounts. 

Palmer ( 1976:276-280) described Mallard wing plumage 

as follows: 

a. the greater secondary coverts are white 

subterminally and black at the tips in both sexes in 

all plumages, with the white of the female often 

extending proximally beyond the metallic area 

(speculum) but not onto innermost secondaries; 

b. the secondaries forming the speculum are black 

subterminally with broad white tips in all plumages, 

forming a trailing white bar in both sexes; and 

c. axillars and most of the wing lining are white in both 

sexes, but the most proximal of the light underwing 

coverts have dark barring in the female. 
DESCRIPTION AND IDENTIFICATION OF WING PLUMAGE 5 

Black Duck 

Earliest written descriptions of the Black Duck 

appeared only after initial European exploration of North 

America's eastern shore. The modem definition is as 

follows (Palmer 1976:321-326): 

a. greater secondary coverts terminal black, with 

sometimes "more or less of a thin or poorly defined 

white line forward of this black stripe"; 

b. secondaries have broad black ends, which vary from 

bird to bird from white at the very tip to ends solid 

black; and 

c. in the wing lining, many greater coverts are light 

gray, others white, but some sooty-fuscous coverts 

with whitish margins generally are present beyond 

the bend of the wing, and axillars are white. 

Palmer emphasized that "typical" Black Duck and 

Mallard wings also differed in other respects including 

overall color, amount of light edging on feathers, extent 

of iridescence (but not necessarily or consistently the 

color) of the speculum, presence of vermiculation, and 

presence of internal markings in feathers. Although 

further variation is introduced by the presence in wing 

collections of domestic Mallards, which display a range 

of characters unlike those of the wild Mallard (Delacour 

1964: 154-166), the modem consensus remains that 

"typical" wings (as described by Palmer for each 

species) are strikingly different to even the casual 

observer. 

Older accounts of Black Duck wing plumage (from 

1785; references in Appendix) differ from Palmer's 

(1976) description. In these older accounts, the occasional presence of white subterminally on the greater 

secondary coverts was never mentioned as a species 

character except by Phillips (1912), who mentioned that 

some Black Ducks in New England showed this trait. 

Palmer's description agrees with commonly accepted 

criteria used by those who currently handle Black Ducks 

in banding operations: the Black Duck may or may not 

have "some" white anterior to the speculum. For 

example, the description in Carney's (1992:141) key 

("[secondaries] blue bordered front or back (not both) 

with white") for Black Duck and Mottled Duck allo-ws 

less expression of white than Palmer ( 197 6). Although· 

Palmer's description may accurately describe wings of 

mid- to late 20th-century birds assumed to be Black 

Ducks, historical evidence from the references in the 

Appendix supports our contention that subterminal white 

on the secondary coverts of Black Ducks is rare, and at 

its most extreme, it is a pale gray subterminal tinge in 

some birds as described by Cramp and Simmons ( 1977). 

Accounts did not mention white as occurring on the 

terminal edge of the secondary feathers of Black Ducks 

until Nuttall ( 1834 ). Thereafter, some authors listed this 

character while others did not, and some attributed it to 

males only. Not until the 20th century did most authors 

list white as possibly being present as a thin terminal 

line, and the sex specificity was retained for at least 25 

more years (e.g., Forbush 1925). Forbush (1925) and 

Bagg and Eliot (1937) attributed this character to adults 

only, but age and sex specificities of this trait were 

omitted by all authors after 1940. It may be that terminal 

white on the secondaries was always variable and 

sometimes inconspicuous, giving the impression that 

"most" Black Ducks were without white, or concomitantly, that the proportion of birds with white-tipped 

secondaries increased in this century. Regardless, the 

important determination for plumage analysis is that 

historical descriptions support the conclusion that Black 

Ducks from across their range may have a more-or-less 

complete terminal band of white on the secondaries that 

form the speculum, and the maximum width may be 

equivalent to that on Mallards. 

Underwing Plumage 

Descriptions of underwing plumage in both the Black 

Duck and the Mallard have historically varied. "White" 

or "silvery white" are always listed as the most conspicuous features of this plumage in the Black Duck. Certainly, from a distance as a field mark, this trait is 

distinguishing. However, paintings by several artists 

showed dark feathers in the underwing of the Black 

Duck [Audubon 1838, Fuertes (in Forbush 1925 and 

Oberholser 1974), Hunt (in Heilner 1946), Ruthven and 

Zimmerman (1965), Weber (in Wetmore 1965), Ogilvie 

(1975), and Hines (1978)]. Similarly, a photograph in 

Wright ( 1954) shows some dark feathers, and Palmer 

(1976) specifically mentioned "sooty-fuscous" feathers 

on the underwing. 

The Mallard has been described as generally having 

"creamy white" underwings. We observed that male 

Mallards trapped in Quebec (1975-90) and male 

specimens in Canadian museums collected before 1935 

did not have dark underwing feathers. Mallard females 

had a variable but always small number (generally less 

than seven) of dark underwing feathers. In obvious 

contrast, Black Ducks of both sexes had a variable, but 

consistently large, number (always more than 10) of 

these dark feathers. A large group of birds, believed to be 

hybrids, fell between Mallards and Black Ducks for this 

character. Ball's (1934:23) comment that a hybrid 

specimen showed its A. rubripes inheritance in the 

underwing coverts through a broken row of dark spots 

near the edge of the wing is the only reported prior 

observation of this phenomenon. 
6 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR-2000-0002 

Species Descriptions and the 

Characters of Study Skins and Wings 

Mallard Wings in Museums and Modern Parts Collections 

We examined 469 specimens collected from 1867 to 

1977 in areas outside North America. These birds were 

presumed to have had no probability of contact with 

Black Ducks. 

Palearctic and Orient. All but one of 332 Mallard 

skins (adult male from Sweden, 1908) were typical, as 

there were no obvious aberrancies in body plumage, 

white edging on the anterior and posterior borders of the 

speculum was complete (>80% of all feathers of the 

speculum), there were no large dark underwing feathers, 

and there were fewer than 10 small dark underwing 

feathers. The single aberrant bird appeared to be a cross 

with a domestic variety. 

Great Britain. All but 3 of 13 7 wings analyzed from 

the British Parts Collection Surveys showed typical 

Mallard features as above. One exception had narrow 

white bars, others had 3 and 9 small dark feathers in the 

underwing. 

North America. We examined 1, 705 wings from the 

U.S. Parts Collection Survey for the Pacific Flyway 

( 1976-77 season), 2,280 wings from the Canadian Parts 

Collection Survey (British Columbia, 197 5-7 6 and 197 6-

78 hunting seasons), and 85 older skins (1840-1937) 

from the collection of the Academy of Natural Sciences, 

Philadelphia, Pennsylvania, to evaluate the modem 

description of Mallards. These specimens were selected 

because of their low probability of contact with Black 

Ducks, Mexican Ducks, or Mallard x Mexican Duck 

hybrids (i.e., wings from northern California, Nevada, 

Oregon, Washington, Idaho, western Montana, western 

Colorado, and western Wyoming). All wings in the 

Pacific Flyway sample had white wing bars above and 

below 80% or more of the speculum and were otherwise 

typical Mallards. Two females had one brown feather on 

an underwing; one female had three brown feathers on 

one underwing. Only one of the wings from British 

Columbia (male) had characters different from those of a 

typical Mallard (dark feathers in the underwing). In the 

Philadelphia collection, 52 male skins were typical 

Mallards in all respects; one male skin (6 August 1927, 

Bear River, Utah) was typical on the dorsal wing surface 

and elsewhere but had two dark brown feathers on the 

underwing; 32 female skins were typical in all respects 

except that four skins each had one dark brown feather in 

the underwing. 

Black Duck Wings in Museums and Modern Parts 

Collections 

We examined 312 Black Duck skins at the Academy 

ofNatural Sciences, Philadelphia, Pennsylvania; 

American Museum ofNatural History, New York, New 

York; and Museum of Comparative Zoology, Harvard 

University, Cambridge, Massachusetts, each of which 

contained substantial collections of comparatively old 

specimens (1873-1939). Ninety-seven percent of the 

males and 99 percent of the females resembled in general 

fom1 and coloration typical Black Ducks per Cramp and 

Simmons (1977). These specimens had either no white 

on the dorsal surface of the wing or only a lower bar 

(white terminal) on the secondaries. Only two of these 

ducks had fewer than 10 brown feathers on the underwing. 

A Revised Description of Mallard Wing 

Plumage 

Based upon our historical literature review and 

empirical assessment of study skins, wings, and live 

birds, we contend that typical Mallard wing plumage can 

be characterized as follows (Figs. 1 and 2): 

Dorsal: The speculum is bounded by anterior and 

posterior white bars, each usually more than 5 mm 

wide, but not always so. These bars are continuous 

and delimit without interruption more than 80% of the 

iridescent secondaries. This white has strictly delimited margins with adjacent colors including black on 

the posterior bar; fuscous-gray, gray, or shades of 

brown, depending upon age, sex, and season, and 

black on the anterior subterminal bar (color terminology ofPalmer 1976). The remainder of the wing 

dorsum for both sexes and all ages is as described by 

Palmer (1976) and Cramp and Simmons (1977). 

Ventral: Underwing coverts (lining of the wing) are 

white in both sexes. Male Mallards never have dark 

feathers in the underwing coverts; but female Mallards are more variable and may have a few (usually 

less than seven but always less than 1 0) dark brown 

feathers on the anterior edge of the underwing. 

A Revised Description of Black Duck 

Wing Plumage 

Based upon our literature review and assessment of 

study skins, wings, and live birds, we contend that Black 

Duck wing plumage is characterized as follows (Fig. 3): 

Dorsal: Black Ducks can have white posterior to the 

speculum, but they never have white anterior to the 

speculum. White posterior to the speculum may vary 

from none, to a thin white edge, to that present on 

typical Mallards. The lack of white anterior to the 

speculum on the greater secondary coverts strictly 

separates Black Ducks from Mallards. However, 

Black Ducks often do have a pale gray subterminal 

line (terminology of Cramp and Simmons 1977) on 

these coverts, and on some birds this gray line is 

suffused with one of several shades of "brown" or 
DESCRIPTION AND IDENTIFICATION OF WING PLUMAGE 7 

Fig 1. Photograph of a typical wing from an immature male Mallard illustrating the range of dorsal and ventral characters expected 

in wild forms. Note the sharp borders between white and black bordering the speculum, the large and even width of this white from 

the proximal to the distal end of the speculum (considered 100% for comparison). and the overall uniform white of the underwings. 

This wing has slightly more white than average on the proximal edge of the speculum. 
8 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR- 2000-0002 

Fig. 2. Dorsal and ventral photographs of a typical wing from an immature female Mallard illustrating the same features as in Figure 1. 

Note the further extent of white across the tertia Is in the female than in the male. 
DESCRIPTION AN D IDENTIFICATION OF WING PLUMAGE 9 

Fig. 3. Dorsal and ventral photographs of a typical wing from a Black Duck (in this case, an adult male) illustrating characters expected 

in wild forms. Note lack of an anterior white bar bordering the speculum, the trace of white on the posterior bar, and the presence of 

more than 10 brown feathers on the underwing. 
10 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR-2000-0002 

"tan." The overall effect is difficult to describe 

precisely, since several colors (#23 [Raw Umber], 

#24 [Buff], #36 [Amber], #37 [Antique Brown], #38 

[Tawny], #39 [Cinnamon], #40 [Cinnamon Rufous], 

and various combinations with one of the Neutral 

Grays [terminology of Smithe 1974a, 1974b]) may be 

present. The result is a line of variable width adjacent 

to the terminal black that is distinctly not white in 

comparison with the white on the dorsal surface of a 

Mallard wing. 

Ventral: All Black Ducks have more than 10 dark brown 

feathers on or near the leading edge in the lining of 

the wing (Fig. 3). 

Independent Confirmation of the Revised 

Black Duck Wing Description 

We applied our diagnostic criteria to an independent 

sample of older Black Duck skins collected from 1842 to 

1939 that are deposited in the Smithsonian Museum of 

Natural History. At arm's length, we viewed each 

available skin in the entire collection labeled as either a 

"Mallard," "Black Duck," "domestic Mallard," "aberrant 

form," "Mallard-like," or "hybrid." We used the presence 

of white and more than 1 0 dark feathers to classify each 

skin as (a) Black Duck-like, (b) Mallard-like, or (c) an 

obvious mixture of the two or a domestic breed. (These 

initial decisions were made without knowledge of the 

information on labels attached to the skins.) We then 

evaluated those specimens in category "a" with the Black 

Duck wing criteria. Ninety of94 specimens (96%) met 

the dorsal and ventral wing criteria. No birds we classified as "b" or "c" were labeled Black Ducks by the 

original collectors or determined to be Black Ducks by 

us after closer inspection. We concluded from this 

sample that in excess of 95% of all Black Ducks meet 

the proposed criteria. 

Black Duck x Mallard Hybrid Wing 

Plumage 

Available descriptions of Black Duck x Mallard 

hybrids by Dutcher ( 1889), Eaton ( 1903 ), Bigelow 

(1907), Kortright (1942), and Gillham and Gillham 

(1996) are oflimited value because the authors could not 

be certain of their specimens' genetic history. Only 

Phillips (1915, 1921) described ducks he knew were 

progeny of mixed pairs. He found F 1 hybrids to be darker 

overall than Mallards, but all had both upper and lower 

white wing bars bordering the speculum. He found 

reduced amounts of white in F 2 progeny and young from 

backcrosses to Black Ducks. Upper wing bars were 

absent in only one F 2 bird. He did not comment on the 

appearance of the underwing of his hybrids. 

We were able to locate eight of Phillips' Black Duck x 

Mallard specimens from his hybridization studies in the 

Museum of Comparative Zoology, Harvard University. 

Seven of these birds did not fit the criteria for typical 

Black Ducks or Mallards, and one bird, F2 male number 

172, was indistinguishable from a typical Black Duck as 

noted by Phillips (1915:78). No other historical specimens of progeny from confirmed hybrid matings were 

known to us. 

Hybrids Propagated at Jamestown 

None of the 23 female and 42 male F1 hybrids 

propagated at the Jamestown facility matched the above 

criteria for typical Black Duck or Mallard wing plumage. 

These birds all had narrower, and usually less distinct, 

white wing bars than Mallards and too few (to be a Black 

Duck) or too many (to be a Mallard) dark feathers on the 

underwing. Twenty-two male F 2

, six of 13 female F 2

, five 

male F 3

, and two of nine female F 3 did not meet criteria 

for typical Black Duck or Mallard wing plumage based 

on presence/absence of white wing bars and underwing 

dark feathers. In backcrosses ofF 1 hybrid ducks to Black 

Ducks, 47 of 49 males and 35 of 44 females did not fit 

the standard criteria for the two species. In backcrosses 

ofF 1 hybrids to Mallards, 40 of 49 males and four of 42 

females did not fit the species criteria. 

In sum, all F 1 hybrids, regardless of sex, could be 

distinguished from parental species by using the species 

definitions for white on the dorsal surface of the wing 

and dark feathers on the underwing. All male F 2 and F 3 

generations showed these characters, but only 36% of the 

female F 2 and F 3 showed them. Our wing characters 

correctly identified 96% of males and 80% of females 

resulting from backcrosses between F 1 hybrids and Black 

Ducks, but we could identify only 82% of males and 

10% of females resulting from backcross ofF 1 hybrids to 

Mallards. 

Figures 4 through 7 provide examples of hybrids from 

the propagated flock, wing receipts in Canadian and U.S. 

Parts Collection Surveys, and birds handled in Quebec 

and New Jersey banding operations during 1976-80. 

Figure captions note those characters that identify the 

bird as of hybrid origin. 

Sex Determination of Hybrid Wings 

Undamaged wings of 131 hand-reared hybrids were 

measured for comparison with Carney's (1964, 1992) 

keys for Black Ducks. Three of 52 (6%) adult male 

wings measured less than 282 mm, Carney's lower limit 

criterion for absolute identification to sex based on this 

measurement. All of the smaller wings were in the inbetween grouping (279-281 mm), which requires 

inspection of plumage characters for sex determination 

in Carney's key. Eight of 59 (14%) wings from adult 
DESCRIPTION AND IDENTIFICATION OF WING PLUMAGE I I 

Fig. 4. Dorsal and ventral photographs of a wing from an adult male hybrid resembling for the most part a Black Duck. Note the trace of 

an anterior bar (hybrid character), restricted posterior bar on the secondaries about 10% the width of a normal male Mallard posterior 

bar (a Black Duck character), and the presence of more than 10 brown feathers on the underwing (Black Duck character). 
12 BIOLOGICA L SCIENCE REPORT USGS/BRD/BSR-2000-0002 

Fig. 5. Dorsal and ventral photographs of a wing from an immature female hybrid resembling for the most part a Black Duck. Note the 

anterior bar about 50% the width of that of a Mallard (hybrid character). the posterior bar about 10% of that of a Mallard (Black Duck 

character), and more than 10 brown feathers on the underwing (Black Duck character). 
DESCRIPTION AND IDENTIFICATION OF WING PLUMAGE 13 

Fig. 6. Dorsal and ventral photographs of a wing from an adult female hybrid resembling for the most part a Mallard. Note the anterior and 

posterior bars about 50% that of a Mallard (hybrid character). and more than 10 brown feathers on the underwing (Black Duck character). 

Many of the brown feathers are small and do not show well in the photograph except near the bend of the wing (wrist). 
14 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR- 2000-0002 

Fig. 7. Dorsal and ventral photographs of a wing from an immature female hybrid resembling for the most part a wing intermediate 

between Black Duck and Mallard. Note that the anterior bar is almost that normally found on Mallards (Mallard character). but the 

posterior bar is only about 50% of that found on Mallards. The underwing has six brown feathers. The unlikeness of the two wing bars 

identifies this wing as a hybrid even though it was only slightly darker than an average mallard wing. Many would identify this wing as 

a mallard. 
DESCRIPTION AND IDENTIFICATION OF WING PLUMAGE 15 

females exceeded 278 mm, Carney's upper limit 

criterion for absolute identification of females on the 

basis of wing length. Of those eight, four fell within the 

range 279-281 mm, which would have required further 

inspection of the plumage. The four remaining wings 

would have been initially identified as from males, on 

the basis of length, for an error rate of 7%. Three of the 

wings in question, however, more closely resembled 

wings from Mallards than Black Ducks and were 

correctly identified by presence of plumage characters 

used to identify sex ofMallards (Carney 1992). The 

remaining wing would be misidentified with any but 

most careful inspection in addition to measurement. We 

conclude that sex of an adult hybrid wing is 

misclassified 2-7% of the time using wing characters, 

and that this error is biased against correct identification 

of females. 

The measurements for the immature birds identified 

all but one of 10 females correctly with current Canadian 

Wildlife Service criteria for wing length of< 271 mm 

(Reed and Boyd 1972). Wing chords of 10 immature 

males exceeded 272 mm, Reed and Boyd's lower limit 

criterion for identification of young males. Bias, again, 

is against correct identification of females. The single 

wing from a female that was misidentified resembled the 

wing of a Black Duck. Only careful inspection would 

have revealed its sex after the measurement was made. 

Because the error rate for detennining sex of hybrid 

wings seems to be approximately in the range < 5%, we 

conclude that current techniques for detennining the sex 

of Black Ducks are sufficient to determine the sex of 

hybrids from wings alone. Measurements usually suffice, 

but a careful worker will take advantage of both measurements and plumage characters to detern1ine sex, 

especially if the wing has any white anterior to the 

speculum. In such instances, criteria for determining sex 

ofMallard wings easily apply (Carney and Geis 1960, 

Carney 1992). 

Discussion 

Key for the Identification of Hybrid 

Wings 

We developed a key from our analyses (Table; also 

see page 27). We are confident the key facilitates 

discrimination among wild Black Ducks, Mallards, and 

their hybrids. In general, most wings will be obvious 

forms of domestic Mallards, Mallards, or Black Ducks; 

only a few wings will require closer scrutiny to determine if they are from hybrids. 

Identification of Domestic Mallards 

Wings from domestic Mallards, even if the birds are 

feral and free-flying for several generations, confound 

attempts to estimate hybrid incidence in the wild Black 

Duck and Mallard population through parts collection 

surveys. Unfortunately, complete descriptions of 

domestic forms of the Mallard are not available, even 

though useful discussions and some illustrations may be 

found in Jaap (1934 ), Lancaster (1963 ), Delacour 

(1964), Batty (1985), and Kear (1990). For identifying 

wings of otherwise unavailable birds, it is easier to state 

what a wild Mallard wing looks like (i.e., Palmer's 1976 

definition) than what it is does not. With reference to 

Palmer's definition, this means that all Mallard-type 

wings with large amounts of white, unusual colors, or 

overall dark underwings, etc., must be removed at the 

first step in a hybrid key. Persons familiar with domestic 

Mallards with whom we discussed this step concurred 

with us that common domestic Mallard strains are easily 

identified as are many uncommon ones, such as the 

recessive melanistic form known as the "Dusky Mallard." Characteristics listed above for the domestic 

Mallard can invariably identify domestic forms, particularly if care is taken to examine the underwing for 

overall dark coloration and dark spotting (F. B. Lee, 

Emeritus Biologist, Northern Prairie Wildlife Research 

Center, personal communication.) 

Limitations of the Wing Key 

Despite many attempts to qualitatively and quantitatively differentiate plumages in the Mallard group, the 

sexual dichromatism in the Mallard and the similarity of 

the southern fonns to one another and to female Mallards have largely defeated such efforts. For example, 

Palmer ( 197 6:314) described both sexes of the Mottled 

Duck as superficially alike and quite similar to Black 

Ducks, but with general coloring not quite as dark as 

Black Ducks (though darker than female Mallards). He 

emphasized the presence of a white bar only at the 

trailing edge of speculum, and even then often obscure 

or lacking, especially in Florida birds. Differences from 

Black Ducks were described as "a matter of degree." 

Similarly, Palmer ( 1976:309) described both sexes of the 

Mexican Duck as resembling female Mallards in general 

appearance but with "darker, richer browns," especially 

on the breast. Palmer described white on the dorsal wing 

surface of both sexes of the Mexican Duck as a bar at the 

leading and another at the trailing edge of the speculum, 

or variably, an indistinct "brownish or dusky" bar. 

These and similar descriptions are inadequate unless 

one has a reference collection. Thus, keys for identifying 

members of the Mallard group (e.g., Bellrose 1976:72) 

usually suggest that knowledge of the geographic origin 
16 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR-2000-0002 

Table. A dichotomous key for identification of wings from American Black Ducks, Mallards, and hybrids between the two. 

Like-numbered couplets will permit only one choice; numbers in parentheses indicate the next couplet to compare. 

1. Wing distinctly unlike those figured for Black Ducks and Mallards by Bellrose ( 1976: plates 6 and 

7) including but not limited to: gray underwing (Smithe 1974a: colors #83-#86); white in areas 

other than bounds of speculum (colored portion of secondaries) on the dorsum; extremely faded 

feather areas or colors not usually observed in American Black Ducks and Mallards, especially 

shades of black mixed with white for a piebald effect. Actual size of the wing is immaterial, although in many domestic breeds the ratio of length to width seems out of proportion compared 

with wild birds, and the wing may be extremely large in some breeds. In sum, resembling any bird 

figured by Delacour (1964:154-166) ........................ DOMESTIC MALLARD OR DOMESTIC CROSS 

1. Not as above ............................................................................................................................................... (2) 

2. Wing Mallard-like on dorsal surface including two complete white bars bounding the speculum. 

This white forms a broad white terminal bar on the secondaries and a similar subterminal bar on 

each greater covert . . . . . .. .. . . . . . . . . . .. . . . .. .. . . . . . .. .. . .. . . . . . . . . . . . . .. .. . . . . . . . . . .. .. . . .. .. . . . . . . . .. . . . .. . . . . . . . . . . .. .. .. . . . . . . . . .. . . .. .. . . . . . . . . . .. .. . (3) 

2. Wing not Mallard-like on dorsal surface. One of the two white bars bounding the speculum may 

be lacking, incomplete, or indistinct; wing usually darker than most Mallard wings .. .. .. .. .... ............ ...... . .. (6) 

3. Wing Mallard-like; white bar anterior to speculum terminates at the proximal edge of the speculum: male .................................................................................................................................................... (4) 

3. Wing Mallard-like; white bar anterior to the speculum extends onto the greater tertial coverts: 

female ........................................................................................................................................................... (S) 

4. Dark brown coverts absent on the undersurface (lining) of the wing. Gray vermiculated feathers 

are pennissible; the brown in question does not appear on the Mallard wing but is similar to that 

observed on Black Duck dorsal wing surfaces ........................................................................... MALLARD 

4. At least one dark brown feather on lining, usually on leading edge and often near bend of 

wing .................................................................................................................................................. HYBRID 

5. Dark brown feathers (<10, small) present on the underwing, usually along the leading 

edge ... . . . . ... . . ... .. . . . . .. . .. . . ... . . . . .. .. . ............ .. . ... . . . . . . . . . . .. ... . . . . . . . . . . ... . . .... .. . . . . . ..... ............. ............... ..... .... MALLARD 

5. Dark brown feathers (> 10, small or medium-sized) on the underwing, usually along the leading 

edge and near the alula ..................................................................................................................... HYBRID 

6. Wing Black Duck-like; white subterminal bar present on> 1 greater covert anterior to speculum; 

white terminal bar on secondaries may be present or lacking .......................................................... HYBRID 

6. Wing Black Duck-like; white subterminal bar on greater coverts lacking. White on posterior edge 

of speculum (tips of secondaries) may be complete, incomplete, or lacking ............................................... (7) 

7. Dark brown feathers (<10, small) present on underwing ................................................................. HYBRID 

7. Dark brown feathers (> 10, small to medium) present on underwing .................................... BLACK DUCK 
DESCRIPTION AND IDENTIFICATION OF WING PLUMAGE 17 

of the specimen is necessary to make positive identification. To demonstrate the confusion that might result 

from applying the hybrid key to other members of the 

Mallard group, we inspected 23 7 specimens collected 

from 1872 to 1929 and originally identified by the 

collectors as An as folvigula, A . .f folvigula, A . .f 

maculosa, Anas diazt~ or A. d novimexicana. Many of 

the specimens examined met the hybrid criteria if we 

ignored other characters of the plumage. This hybrid 

identification was especially true regarding Mottled 

Ducks, which in this sample had a mean of 17 dark 

feathers in the underwing, and many Mexican Ducks that 

did not have the expected two white bars bounding the 

speculum. We conclude that our key should be used only 

for specimens obtained from portions of the continent 

where Mexican and Mottled Ducks are unlikely to be 

encountered: North Carolina and north in the Atlantic 

Flyway and Arkansas and Tennessee north in the 

Mississippi Flyway (unless birds obtained from the 

Louisiana and Mississippi coastal areas where Mottled 

Ducks are found can be separated from birds shot 

elsewhere in these latter states). 

What Proportion of the Hybrids in a 

Sample Can Be Identified? 

The rank order of abundance of hybrids in any freelymixing population of Black Ducks, Mallards, and their 

hybrids will be P1 > F1 > F2 > F3 ••• > Fn. This order is 

dictated because F 2

, F 3 ••• F n hybrids are very rare as a 

consequence of the F 1 itself being rare compared to the 

parental populations. In other words, most F 1 matings 

would be a backcross to one or the other of the parental 

forms in subsequent years instead of inter se (Merrell 

1981 ). As a result, hybrids detectable in a wild population of Black Ducks and Mallards would be F1 birds and 

a large but unknown fraction of the F 1 backcrosses to P 1

• 

Both the absolute number and proportional representation ofF 2

, F 3 ••• F n' and other combinations, whether 

detectable or not, would be quite small. 

Our data showed that 82-96% of the male progeny 

and 10-80% of the female progeny of backcrosses to P 1 

will be detectable, depending upon the P 1 in the cross. 

Because wings from many of the backcrosses of hybrids 

to either P1

, especially females, defy identification with 

any plumage key, inability to detect all backcrosses 

prevents determining the true proportion of hybrids in 

the wild from even large samples of wings. It seems 

imprudent to generate a correction factor to acGount for 

these undetectable hybrids resulting from F 1 x P 1 matings 

since we lack information on the proportion ofF 1 that 

mate with Black Ducks versus Mallards. Thus we do not 

know whether misidentification is as a Black Duck or a 

Mallard. Regardless, the wing characters employed are 

capable of identifying a large and constant fraction of the 

hybrids present in a sample, namely 100% of the F 1

, at 

least 82% of male progeny of backcrosses to either P 1

, 

and 80% of the female progeny ofbackcrosses to Black 

Ducks, but perhaps as few as 1 0% of the female progeny 

ofbackcrosses to Mallards. The hybrid key and the 

North American parts collection surveys certainly can be 

used to generate an index to error in mate choice of the 

two parental populations. We recommend it for this use 

as well as for identifying birds in hand during banding 

operations. 

Reinterpretation of the 1977 U.S. Parts 

Collection Survey 

We reexamined the 4,608 wings obtained in the 1977 

U.S. Parts Collection Survey for the Atlantic Flyway 

originally identified as Black Duck, Mallard, or hybrid 

between the two. With the new criteria presented in our 

key (Table), we found that the number of hybrids had 

been underestimated by at least a factor of2.37 (237 

wings versus 100 wings). This underestimation would 

change the proportion ofhybrids/(hybrids +Black 

Ducks) from 0.056 to 0.132, the proportion of hybrids/ 

(hybrids+ Mallards) from 0.034 to 0.078, and the ratio 

ofhybrids/(hybrids +Black Ducks+ Mallards), which is 

the incidence of overall hybridization, from 0.022 to 

0.052. When we applied our new criteria, we identified 

34 (34%) ofwings classified as hybrids as domestic 

strains, Mallards, or Black Ducks. We reclassified as 

hybrids 136 (8%) of the wings originally identified as 

Black Duck. Similarly, we identified as hybrids 34 

( 1.2%) of the wings originally classified as Mallards. 

The most important conclusion for management is that 

hybridization between the Black Duck and Mallard 

occurred at about twice the rate heretofore reported for 

the Atlantic Flyway in 1977. 

We could not make a similar comparison in any 

subsequent year. Our work generated substantial interest 

among participants in the "wing bees" (cooperative 

evaluations of parts collection survey receipts) in 

identifying Black Duck x Mallard hybrids. Managers of 

the U.S. Parts Collection Survey modified the criteria 

used to identify hybrids after 1977, and we confirmed 

that subsequent wing bees have identified larger percentages of hybrids among the available wings. Managers of 

t.he Canadian Parts Collection Survey likewise emphasized recording Black Duck-like and Mallard-like 

hybrids. 

Comparison with Another Quantitative 

Measure of Hybridization 

Barnes (1989) presented another key for identifying F1 

hybrids between the Black Duck and Mallard. He 
18 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR-2000-0002 

concluded that the area of the color band on the fifth 

greater secondary covert (whether white or some other 

color) was a measure that discriminated between the P1 

forms and the F1 hybrids, and the length of the white 

band at the tip of the fifth secondary correctly identified 

19 of 22 hybrids from a sample of P 1 and F 1 birds. 

As is generally the case with F1 hybrids, Black Duck x 

Mallard F1 are uniform in phenotype and intermediate 

between the parental forms in most characters. Our 

review has shown that subterminal white on the secondary coverts is not a Black Duck character. Barnes's 

criterion for area of"color" on the secondary coverts is 

thus the same as our presence/absence criterion for white 

in these feathers except that he requires a measurement. 

We believe that a presence/absence criterion is preferable because dimensions and amount of white in this 

color band will be distributed approximately normally 

(as are most other morphological characters) in a sample. 

This normal distribution can be seen in the intermediate 

frequency distribution of this character for hybrids 

80 

60 

40 

20 

OJ_~--~--~~~L__ 

between the frequency distributions for Mallards and 

Black Ducks in Barnes (1989:Fig. 2). 

Further, we have shown that the amount of terminal 

white on the secondaries of Black Ducks is variable and 

is a poor criterion of genetic origin. It is particularly poor 

as a criterion when applied to F2 and subsequent generations that are quite mutable because of Mendell ian 

segregation and recombination, and which may theoretically include the extremes of the P1 populations. The 

frequency distributions of white on the wings of birds 

raised in the experimental flock in Jamestown (Fig. 8) 

clearly show the intermediate nature of the F1

, the 

expected broader range of values of the F2 (because of 

genetic segregation and recombination), and the shift in 

F 1 x P 1 crosses in the direction of the P 1 phenotype. 

Barnes's key may be relied upon for experimental work 

with F1 and P1 known-parentage birds, but our key 

(Table) should be used for all birds of unknown genetic 

origin. 

1 oo --,----v;;77777777r----,---,----""F'77'7'77''7'77'r=-= 

80 

60 

40 

20 

F, x A. rubripes A. rubripes F, A. platyrhynchos F, x A. platyrhynchos F, 

.. 100% 50% ~ trace C:=J abse nt 

Fig. 8. Frequency distribution of the width of white bars bounding the speculum on the wing dorsum of Black Ducks, Mallards, and 

hybrids from an experimental flock reared at Northern Prairie Wildlife Research Center. All measurements are compared with Mallard 

= 100%; actual range in width 0-10 mm. 
DESCRIPTION AND IDENTIFICATION OF WING PLUMAGE 19 

The Need for Additional 

Research 

Throughout our analyses, we recognized that a key 

designed for use with the parts collection surveys was 

limited by the differences among Black Ducks, Mallards, 

and hybrids that could be consistently recognized by 

inspection of single wings. Such limitations are not 

applicable to morphological assessment of whole birds. 

Nonetheless, Hanson and Ankney ( 1994) showed that 

discriminant function analysis of standard morphometric 

measurements could not separate Mallards and Black 

Ducks. In contrast, Byers and Carey ( 1991) were able to 

correctly classify wild versus urban and game-farm 

Mallards with a similar analysis. Within-population 

variation in the Mallard and slight differences between 

Black Ducks and Mallards thus seem sufficient to 

confound simple morphometric analysis of hybridization 

between Black Ducks and Mallards. Regardless, there is 

a need to develop a key for whole birds. To that end, 

plumage descriptions such as those in Palmer (1976) for 

Mallards and Black Ducks need to be developed for F 1 

hybrids and backcrosses ofF 1 to both parental forms. 

These plumage descriptions would best be accomplished 

with a simultaneous attempt to more completely describe 

the variation in Black Duck plumage from throughout its 

range. Finally, a guide to the plumage characters of 

domestic breeds of the Mallard and captive-reared 

Mallards would be a helpful adjunct to interpreting both 

wings in the parts collection surveys and birds captured 

in the wild. 

Identification of wings as from hybrid ducks is a post 

facto assessment of the phenomenon that is of greatest 

interest: the interaction of Black Ducks and Mallards in 

the wild and the resulting population consequences for 

each species. Attempts to separate the effects of natural 

range expansion of the Mallard, anthropogenic habitat 

change, release of captive-reared Mallards by individuals 

and governments, behavioral differences between the 

species, the effects of sport hunting, and hybridization 

upon population dynamics of Black Ducks and Mallards 

have been unsuccessful , but not for want of trying. 

Failure may be attributed to the fact that experiments to 

detect true differences are difficult to design and 

conduct, andas a result, studies to date have resulted in 

universally weak inferences (Nichols 1991 ). Consequently, the literature remains replete with insufficiently 

tested, usually single-factor, hypotheses and controversial conjecture (Nudds et al. 1996). Another attempt at a 

complete listing of research needs for the Black Duck 

thus would be redundant, but two questions with bearing 

on the effects of hybridization on the parental populations do seem amenable to investigation. 

The first (also raised by Rusch et al. 1989) is, what are 

the ratios of Black Duck x Mallard pairs to correctly 

formed pairs in various habitats? The answer to this 

question would provide an apparent measure of error in 

mate choice in the wild that could be compared geographically with parts collection survey data and could 

be compared with changes in species ratios over time in 

various habitats. In other words, testable hypotheses 

about the dynamics of hybridization per se could be 

formed. 

The second question is, what are the genetic consequences of hybridization at the rates observed in the 

wild? Further biochemical studies of Black Ducks and 

their hybrids, such as those by Patton andAvise (1983, 

1985), Kessler and A vise ( 1984 ), Oates et al. ( 1984 ), 

Ankney et al. (1986 ), and A vise et al. (1990), should be 

devised to elucidate the genetic and population consequences of hybridization to both Black Ducks and 

Mallards. This effort would initially require laboratory 

study, but ultimately sampling of wild birds would be 

needed to elucidate true levels of admixture of gene 

pools. From this, modeling exercises could be used to 

address genetic and population consequences of interaction between the two species. 

Suggestions for management of Black Ducks have 

been collected in a series of papers on the species 

(Spencer 1980, 1981, 1986; Rogers and Patterson 1984; 

Kirby 1988; Rusch et al. 1989; Conroy and Krementz 

1990; and especially criticism of these and similar 

studies by Anderson et al. 1987; Nichols 1991; and 

Nudds et al. 1996). Comparison of the calls for action in 

these later papers with strikingly similar pleas raised 30 

years before (Barske 1968) shows that questions 

regarding management of eastern waterfowl populations 

have not diminished. Rigorous testing of hypotheses is 

yet needed to identify cause-and-effect relationships 

within Black Duck populations. Further studies of 

hybridization and other population phenomena of Black 

Ducks and Mallards in areas of sympatry are warranted. 

Acknowledgments 

Kirby began this effort while employed by the U.S. 

Fish and Wildlife Service's Patuxent Wildlife Research 

Center. The U.S. Fish and Wildlife Service's Division of 

Refuge Management and Office of Information Transfer 

provided the opportunity to continue with these studies 

in the 1980's. Reed and Dupuis's field and museum work 

was funded by the Canadian Wildlife Service, Quebec 

Region. 

C. J. Henny and R. P. Morgan, II, founded the hybrid 

flock maintained at Northern Prairie Wildlife Research 

Center. F. B. Lee conducted the mating trials. Study skins 
20 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR-2000-0002 

were prepared at the Smithsonian Museum of Natural 

History by C. J. Angle and R. M. Browning. Access to 

museum specimens was provided by R. C. Banks 

(Smithsonian Museum ofNatural History), R. A. 

Paynter, Jr. (Museum of Comparative Zoology), W. E. 

Lanyon (American Museum of Natural History), F. B. 

Gill (Academy ofNatural Sciences), A. Allison and J. G. 

Harrison (private collections, Great Britain), and their 

respective staffs. 

Library work was facilitated by L. J. Garrett, K. M. 

Lahlum, the staff of the Harvard University Libraries, 

staff of the Smithsonian Institution Museum of Natural 

History Library, and the late F. M. Uhler, who allowed 

access to his personal collection of original works on 

birds. We thank C. D. Ankney, the late W. W. Blandin, H. 

Boyd, S. M. Carney, D. G. Dennis, H W Heusmann, J. R. 

Longcore, R. S. Palmer, and J. K. Ringelman for 

providing personal insight on Black Duck ecology 

during the course of this study. J. R. Longcore, E. M. 

Martin, J. R. Serie, G. W. Smith, J. S. Wendt, and 

especially M. R. Miller, N. R. Seymour, and an anonymous referee are thanked for their reviews of drafts. 

D.H. Johnson graciously served as editor of this monograph. 

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Appendix 

This Appendix is a chronological list of critical 

literature selected from more than 200 items reviewed to 

assess historical trends in published descriptions of 

Black Ducks and Mallards. All sources known to us were 

searched for descriptions of the presence/absence of 

white on the wing dorsum and ventral wing coloration. 

References found redundant because of reprinting, 

incomplete revision, wholesale paraphrasing by contemporaneous authors, or later publication of field guides 

and regional omithologies based upon previous works 

were deleted from further consideration after initial 

review. Although many of the remaining works in this 

Appendix are not entirely independent of one anothercontemporaneous authors were no doubt aware of one 

another's work-unique text in these citations and the 

overall level of detail in descriptions provide evidence 

that these authors were describing many birds from 

specimens in hand or from notes taken from such 

specimens by others. The citations in this Appendix are 

thus a source of definitive categorization of the changes 

in descriptions of Black Ducks from 1785 to date. 

Illustrators, if known to be different from the authors, are 

shown in parentheses. 

Latham, J. 1785. A general synopsis of birds. Volume 3, 

Part 2. Leigh and Sotheby, London, England, UK. 

329-628 + unnumbered pages. 

Pennant, T. 1785. Arctic zoology. Volume 2, Class 2. 

Birds. Henry Hughs, London, England, UK. 586 pp., 

index, maps, and 163 pp. supplement. 

Linne, C. von. 1788. Systema naturae per regnatria 

naturae. Tom 1, Pars II. Gmelin, Leipzig, Germany. 

501-1032. 

Wilson, A. 1814. American ornithology or the natural 

history of the birds of the United States. Volume 8. 

Bradford and Inskeep, Philadelphia, Pennsylvania, 

USA. 146 pp. 

Bonaparte, C. L. 1828. The genera of North American 

birds and a synopsis of the species found within the 

territory of the United States. Extracted from the 

Annals of the Lyceum ofNatural History ofNew 

York. J. Seymour, New York, New York, USA. 451 pp. 

Nuttall, T. 1834. A manual of the ornithology of the 

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24 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR-2000-0002 

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State Museum, Memoir 12. New York State Education 
DESCRIPTION AND IDENTIFICATION OF WING PLUMAGE 25 

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the Michigan Agricultural College, East Lansing, 

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Chapman, F. M. 1912. Handbook of birds of eastern 

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birds of Massachusetts and adjacent states. 2nd ed. 

Massachusetts State Board of Agriculture, Boston, 

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Department of Mines, Geological Survey. Memoir 

104(3), Biology Series. 297 pp. (Illustrations by F. C. 

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Hoffman, R. 1923. A guide to the birds: prepared with 

special reference to New England and eastern New 

York, but serviceable in all the northern states east of 

the Mississippi River. New ed. Houghton Mifflin 

Company, Boston, Massachusetts, USA. 357 pp. 

Phillips, J. C. 1923. A natural history of the ducks. 

Volume 2. The genus A11as. Houghton Mifflin 

Company (The Riverside Press). New York, New 

York and Boston, Massachusetts, USA. xii + 409 pp. 

(Illustrations by A. Brooks.) 

Forbush, E. H. 1925. Birds ofMassachusetts and other 

New England states. Part 1, Water birds, marsh birds 

and shore birds. Massachusetts Department of 

Agriculture, Boston, Massachusetts, USA. 481 pp. 

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Sutton, G. M. 1928. Birds of Pennsylvania. McFarland 

Company, Harrisburg, Pennsylvania, USA. 170 pp. 

Chapman, F. M. 1932. Handbook of birds of eastern 

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New York, New York, USA. 581 pp. 

Grosvenor, G., and A. Wetmore. 1932. The book of 

birds. Volume 1. National Geographic Society, 

Washington, D.C., USA 356 pp. 

Howell, A. H. 1932. Florida bird life. Florida Department of Game and Fresh Water Fish and Bureau of 

Biological Survey, U.S. Department of Agriculture. 

579 pp. 

Roberts, T. S. 1932a. The birds ofMinnesota. Volume 1. 

University of Minnesota Press, Minneapolis, Minnesota, USA. 691 pp. (Illustrations by A. Brooks.) 

Roberts, T. S. 1932b. The birds ofMinnesota. Volume 2. 

University of Minnesota Press, Minneapolis, Minnesota, USA. 821 pp. 

Roberts, T. S. 1934. Bird portraits in color. Two hundred 

ninety-five North American species. University of 

Minnesota Press, Minneapolis, Minnesota, USA. 92 

plates, unnumbered text, and index. 

Taverner, P. A. 1934. Birds of Canada. Canada Department ofMines, National Museum of Canada. Bulletin 

72, Biology Series No. 19. 445 pp. 

Bagg, A. C., and S. A. Eliot, Jr. 1937. Birds of the 

Connecticut Valley in Massachusetts. Thomas Todd 

Company, Boston, Massachusetts, USA. 813 pp. 

Forbush, E. H. (revised and abridged by J. B. May). 

1939. Natural History ofthe birds of eastern and 

central North America. Houghton Mifflin Co., 

Boston, Massachusetts, USA. 554 pp. (Illustrations by 

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Kortright, F. H. 1942. Ducks, geese and swans ofNorth 

America. Stackpole Company, Harrisburg, Pennsylvania, and the Wildlife Management Institute, Washington, D.C., USA. 476 pp. (Illustrations by T. M. 

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Pearson, T. G., C. S. Brimley, and H. H. Brimley. 1942. 

Birds of North Carolina. North Carolina Department 

of Agriculture, State Museum. 416 pp. 

Musgrove, J. W., and M. R. Musgrove. 1943. Waterfowl 

in Iowa. State Conservation Commission, Des 

Moines, Iowa, USA. 113 pp. + index. 

Pirnie, M.D. 1943. Michigan upland game, shore and 

marsh birds and waterfowl. First published on the 

Wildlife Page of the Detroit News from July 20, 1941 

to March 14, 1943. The Detroit News, Detroit, 

Michigan, USA. 80 pp. (Drawings from paintings by 

G. M. Sutton and L. B. Hunt.) 

Heilner, V. C. 1946. Our American game birds. 

Doubleday and Company, Inc., Garden City, New 

York, New York, USA. 178 pp. (Illustrations by L. B. 

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Short, A. H., and B. W. Cartwright. 1948. Sports Afield 

collection of know your ducks and geese. Sports 

Afield Publishing Company, Minneapolis, Minnesota, 

USA. Prints and text; no pagination. 

Peters, H. S., and T. D. Burleigh. 1951. The birds of 

Newfoundland. Department ofNatural Resources, 

Province ofNewfoundland, St. Johns, Newfoundland, 

Canada. 431 pp. (Illustrations by R. T. Peterson.) 

Pough, R. H. 1951. Audubon water bird guide. National 

Audubon Society. Doubleday and Company, Inc., 

Garden City, New Jersey, USA. 352 pp. 

Delacour, J. 1954. The waterfowl of the world. Volume 

2. The dabbling ducks. Country Life Limited, 

London, England, UK. 232 pp. (Illustrations by P. 

Scott.) 

Wright, B. S. 1954. High tide and an east wind: the story 

of the Black Duck. The Stackpole Company, Harrisburg, Pennsylvania, and the Wildlife Management 

Institute, Washington, D.C., USA. 162 pp. 
26 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR-2000-0002 

Scott, P. 1957. A coloured key to the wildfowl of the 

world. Wildfowl Trust. Slimbridge, Gloucestershire, 

England, UK. 91 pp. 

Tufts, R. W. 1961. The birds ofNova Scotia. Nova 

Scotia Museum, Halifax, Nova Scotia, Canada. 481 pp. 

Ruthven, J. A., and W. Zimmem1an. 1965. Top flight: 

speed index to waterfowl of North America. Moebius 

Printing Company, Milwaukee, Wisconsin, USA. 112 pp. 

Wetmore, A. 1965. Water, prey and game birds of North 

America. National Geographic Society, Washington, 

D.C., USA. 464 pp. (Illustrations by W. A. Weber.) 

Godfrey, W. E. 1966. The birds of Canada. National 

Museum of Canada Bulletin 203, Bird Series No. 73. 

428 pp. (Illustrations by J. A. Crosby.) 

Robbins, C. S., B. Bruun, and H. S. Zim. 1966. A guide 

to field identification: birds of North America. Golden 

Press, New York, New York, USA. 340 pp. (Illustrations by A. Singer.) 

Oberholser, H. C. 1974. The bird life ofTexas. Volume 

1. University of Texas Press, Austin, Texas, USA. 530 

pp. (Illustrations by L. A. Fuertes.) 

Johnsgard, P. A. 1975. Waterfowl ofNorthAmerica. 

Indiana University Press, Bloomington, Indiana, 

USA. 575 pp. 

Ogilvie, M.A. 1975. Ducks of Britain and Europe. T. 

and A. D. Poyser, Berkhamsted, Hertfordshire, 

England. 206 pp. 

Bellrose, F. C. 1976. Ducks, geese and swans ofNorth 

America. 2nd ed. Stackpole Books, Harrisburg, 

Pennsylvania, USA. 549 pp. 

Palmer, R. S., editor. 1976. Handbook ofNorthAmerican birds. Volume 2. Waterfowl (Part 2). Yale 

University Press, New Haven, Connecticut, USA. 521 pp. 

Cramp, S., and K. E. L. Simmons. 1977. Handbook of 

the birds of Europe, the Middle East and North 

Africa: the birds of the western Palearctic. Vol. 1. 

Ostriches to ducks. Oxford University Press, Oxford, 

England. 722 pp. (Illustrations by N. W. Cusa.) 

Heintzelman, D. S. 1978. North American ducks, geese, 

and swans. Winchester Press, New York, New York, 

USA. 236 pp. 

Hines, B. 1978. Ducks at a distance: a waterfowl 

identification guide. Department of the Interior, U.S. 

Fish and Wildlife Service, Washington, D.C., USA. 

53 pp. 

Johnsgard, P. A. 1978. Ducks, geese and swans of the 

world. University ofNebraska Press, Lincoln, 

Nebraska, USA. 387 pp. 

Farrand, J., editor. 1983. The Audubon Society master 

guide to birding 1. Loons to sandpipers. Alfred A. 

Knopf, New York, New York, USA. 447 pp. 

Madge, S., and H. Bum. 1988. Waterfowl: an identification guide to the ducks, geese and swans of the world. 

Houghton Mifflin Company, Boston, Massachusetts, 

USA. 298 pp. 
A dichotomous key for identification of wings from American Black Ducks, Mallards, and hybrids between the two. 

Like-numbered couplets will permit only one choice; numbers in parentheses indicate the next couplet to compare. 

1. Wing distinctly unlike those figured for Black Ducks and Mallards by Bellrose ( 1976: plates 6 

and 7) including but not limited to: gray underwing (Smithe 1974a: colors #83-#86); white in 

areas other than bounds of speculum (colored portion of secondaries) on the dorsum; extremely 

faded feather areas or colors not usually observed in American Black Ducks and Mallards, especially shades ofblack mixed with white for a piebald effect. Actual size of the wing is immaterial, 

although in many domestic breeds the ratio of length to width seems out of proportion compared 

with wild birds, and the wing may be extremely large in some breeds. In sum, resembling any bird 

figured by Delacour (1964:154-166) ........................ DOMESTIC MALLARD OR DOMESTIC CROSS 

1. Not as above ............................................................................................................................................... (2) 

2. Wing Mallard-like on dorsal surface including two complete white bars bounding the speculum. 

This white forms a broad white terminal bar on the secondaries and a similar subtenninal bar on 

each greater covert . . . . . . .. . . . . . . . . .. . . . .. . . . . . . . . .. .. . . . . . . . . .. .. . .. . . . . . . . . . . . .. . . . . . . . . .. . . . . .. . . . . .. . . . . .. . . . . . . . .. . . . . . . . . .. . . . .. . . . . . . . .. . . .. . . . . . . (3) 

2. Wing not Mallard-like on dorsal surface. One of the two white bars bounding the speculum may 

be lacking, incomplete, or indistinct; wing usually darker than most Mallard wings .... .. .. .. .... .. .. .. .. .. .. .. .. .. . (6) 

3. Wing Mallard-like; white bar anterior to speculum tenninates at the proximal edge of the speculum: male .................................................................................................................................................... (4) 

3. Wing Mallard-like; white bar anterior to the speculum extends onto the greater tertial coverts: 

fetnale ........................................................................................................................................................... (5) 

4. Dark brown coverts absent on the undersurface (lining) of the wing. Gray vermiculated feathers 

are pennissible; the brown in question does not appear on the Mallard wing but is similar to that 

observed on Black Duck dorsal wing surfaces . . .... . . . . . .. . . . .. . . . . . . . . . .. . . . . .. . . . . ... . . . .. . . . . . . . .... . . . . . . . . .. . . . ... . MALLARD 

4. At least one dark brown feather on lining, usually on leading edge and often near bend of 

wing .................................................................................................................................................. HYBRID 

5. Dark brown feathers (<10, small) present on the underwing, usually along the leading 

edge . . . . .. . . . . . . ... . . . .. . . . . . . . . . . . .. . .. . . . . . . . . . . . .. . . . . . . . . . ... . . . . . . . . . . . . . . . . .. . . . . . . . .. . . . .. . . . . . . . . . . .. . . . . . . . . .. . . .. . . . . .. . . . ... . . . . . . . .. . MALLARD 

5. Dark brown feathers(> 10, small or medium-sized) on the underwing, usually along the leading 

edge and near the alula ..................................................................................................................... HYBRID 

6. Wing Black Duck-like; white subterminal bar present on> 1 greater covert anterior to speculum; 

white terminal bar on secondaries may be present or lacking .......................................................... HYBRID 

6. Wing Black Duck-like; white subterminal bar on greater coverts lacking. White on posterior edge 

of speculum (tips of secondaries) may be complete, incomplete, or lacking ............................................... (7) 

7. Dark brown feathers (<10, small) present on underwing ................................................................. HYBRID 

7. Dark brown feathers (> 10, small to medium) present on underwing .................................... BLACK DUCK 

A dichotomous key for identification of wings from American Black Ducks, Mallards, and hybrids between the two. 

Like-numbered couplets will permit only one choice; numbers in parentheses indicate the next couplet to compare. 

1. Wing distinctly unlike those figured for Black Ducks and Mallards by Bellrose ( 1976: plates 6 

and 7) including but not limited to: gray underwing (Smithe 1974a: colors #83-#86); white in 

areas other than bounds of speculum (colored portion of secondaries) on the dorsum; extremely 

faded feather areas or colors not usually observed in American Black Ducks and Mallards, especially shades ofblack mixed with white for a piebald effect. Actual size of the wing is immaterial, 

although in many domestic breeds the ratio of length to width seems out of proportion compared 

with wild birds, and the wing may be extremely large in some breeds. In sum, resembling any bird 

figured by Delacour (1964: 154-166) ........................ DOMESTIC MALLARD OR DOMESTIC CROSS 

1. Not as above ............................................................................................................................................... (2) 

2. Wing Mallard-like on dorsal surface including two complete white bars bounding the speculum. 

This white fonns a broad white terminal bar on the secondaries and a similar subterminal bar on 

each greater covert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (3) 

2. Wing not Mallard-like on dorsal surface. One of the two white bars bounding the speculum may 

be lacking, incomplete, or indistinct; wing usually darker than most Mallard wings .. ... . . . . . . . . . . ...... .. . . . . . .. .. . (6) 

3. Wing Mallard-like; white bar anterior to speculum terminates at the proximal edge of the speculum: 1nale .................................................................................................................................................... (4) 

3. Wing Mallard-like; white bar anterior to the speculum extends onto the greater tertial coverts: 

female ........................................................................................................................................................... (5) 

4. Dark brown coverts absent on the undersurface (lining) of the wing. Gray vermiculated feathers 

are permissible; the brown in question does not appear on the Mallard wing but is similar to that 

observed on Black Duck dorsal wing surfaces ........................................................................... MALLARD 

4. At least one dark brown feather on lining, usually on leading edge and often near bend of 

wing .............................................................................................. .................................................... HYBRID 

5. Dark brown feathers (<10, small) present on the underwing, usually along the leading 

edge .. . . . . . .. . . . . . . . .. . . . ... . . . . . . . . . . .. . . . . . .. . . . . . . . . . . . . . . . . ................. ... . ... . . . . . . . . . . . . . . ... . . .. . . . . . . . . . . . . . . . . ..................... MALLARD 

5. Dark brown feathers(> 10, small or medium-sized) on the underwing, usually along the leading 

edge and near the alula ..................................................................................................................... HYBRID 

6. Wing Black Duck-like; white subtenninal bar present on> 1 greater covert anterior to speculum; 

white terminal bar on secondaries may be present or lacking .......................................................... HYBRID 

6. Wing Black Duck-like; white subterminal bar on greater coverts lacking. White on posterior edge 

of speculum (tips of secondaries) may be complete, incomplete, or lacking ............................................... (7) 

7. Dark brown feathers (<10, small) present on underwing ................................................................. HYBRID 

7. Dark brown feathers (> 10, small to medium) present on underwing .................................... BLACK DUCK 

A dichotomous key for identification of wings from American Black Ducks, Mallards, and hybrids between the two. 

Like-numbered couplets will permit only one choice; numbers in parentheses indicate the next couplet to compare. 

1. Wing distinctly unlike those figured for Black Ducks and Mallards by Bellrose (1976: plates 6 

and 7) including but not limited to: gray underwing (Smithe 1974a: colors #83-#86); white in 

areas other than bounds of speculum (colored pmiion of secondaries) on the dorsum; extremely 

faded feather areas or colors not usually observed in American Black Ducks and Mallards, especially shades ofblack mixed with white for a piebald effect. Actual size of the wing is immaterial, 

although in many domestic breeds the ratio of length to width seems out of proportion compared 

with wild birds, and the wing may be extremely large in some breeds. In sum, resembling any bird 

figured by Delacour (1964: 154-166) ........................ DOMESTIC MALLARD OR DOMESTIC CROSS 

1. Not as above ............................................................................................................................................... (2) 

2. Wing Mallard-like on dorsal surface including two complete white bars bounding the speculum. 

This white fmms a broad white tenninal bar on the secondaries and a similar subterminal bar on 

each greater covert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (3) 

2. Wing not Mallard-like on dorsal surface. One of the two white bars bounding the speculum may 

be lacking, incomplete, or indistinct; wing usually darker than most Mallard wings ............ ... . . ... . . . . . .. . . .. . . (6) 

3. Wing Mallard-like; white bar anterior to speculum tenninates at the proximal edge of the speculum: male .................................................................................................................................................... (4) 

3. Wing Mallard-like; white bar anterior to the speculum extends onto the greater tertial coverts: 

fen1ale ........................................................................................................................................................... (5) 

4. Dark brown coverts absent on the undersurface (lining) of the wing. Gray venniculated feathers 

are pennissible; the brown in question does not appear on the Mallard wing but is similar to that 

observed on Black Duck dorsal wing surfaces ........................................................................... MALLARD 

4. At least one dark brown feather on lining, usually on leading edge and often near bend of 

wing .................................................................................................................................................. HYBRID 

5. Dark brown feathers (<10, small) present on the underwing, usually along the leading 

edge . . . . . . . . . ............... .. . . . ... . . . ....... ... . . . . . . . . .. . . . . . . . . . ... . ... . . . . . . . ... . . . . ... . . . . . . . . . . ................ .. .. . . ........ ....... .. . . . . MALLARD 

5. Dark brown feathers (> 10, small or medium-sized) on the underwing, usually along the leading 

edge and near the alula..................................................................................................................... HYBRID 

6. Wing Black Duck-like; white subterminal bar present on> 1 greater covert anterior to speculum; 

white terminal bar on secondaries may be present or lacking .......................................................... HYBRID 

6. Wing Black Duck-like; white subterminal bar on greater coverts lacking. White on posterior edge 

of speculum (tips of secondaries) may be complete, incomplete, or lacking ............................................... (7) 

7. Dark brown feathers (<10, small) present on underwing ................................................................. HYBRID 

7. Dark brown feathers (> 10, small to medium) present on underwing .................................... BLACK DUCK 

A dichotomous key for identification of wings from American Black Ducks, Mallards, and hybrids between the two. 

Like-numbered couplets will permit only one choice; numbers in parentheses indicate the next couplet to compare. 

1. Wing distinctly unlike those figured for Black Ducks and Mallards by Bellrose (1976: plates 6 

and 7) including but not limited to: gray underwing (Smithe 1974a: colors #83-#86); white in 

areas other than bounds of speculum (colored portion of secondaries) on the dorsum; extremely 

faded feather areas or colors not usually observed in American Black Ducks and Mallards, especially shades of black mixed with white for a piebald effect. Actual size of the wing is immaterial, 

although in many domestic breeds the ratio of length to width seems out of proportion compared 

with wild birds, and the wing may be extremely large in some breeds. In sum, resembling any bird 

figured by Delacour (1964: 154-166) ........................ DOMESTIC MALLARD OR DOMESTIC CROSS 

1. Not as above ............................................................................................................................................... (2) 

2. Wing Mallard-like on dorsal surface including two complete white bars bounding the speculum. 

This white fonns a broad white terminal bar on the secondaries and a similar subterminal bar on 

each greater covert . . . . . . . . . .. . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. .. .. . . . .. . . . . . . . . . . . . . . . .. . . .. .. . . . . . . . . . . . . .. .. . . . . . . . . . . . . .. . . . .. . . . . .. . . .. . . . . . (3) 

2. Wing not Mallard-like on dorsal surface. One of the two white bars bounding the speculum may 

be lacking, incomplete, or indistinct wing usually darker than most Mallard wings ... .. . .. .. .. .. .... . . .. ..... .... .. (6) 

3. Wing Mallard-like; white bar anterior to speculum terminates at the proximal edge of the speculutn: male .................................................................................................................................................... (4) 

3. Wing Mallard-like; white bar anterior to the speculum extends onto the greater tertial coverts: 

female ........................................................................................................................................................... (S) 

4. Dark brown coverts absent on the undersurface (lining) of the wing. Gray vermiculated feathers 

are permissible; the brown in question does not appear on the Mallard wing but is similar to that 

observed on Black Duck dorsal wing surfaces ........................................................................... MALLARD 

4. At least one dark brown feather on lining, usually on leading edge and often near bend of 

wing .......................................................................... ........................................................................ HYBRID 

5. Dark brown feathers ( <1 0, small) present on the underwing, usually along the leading 

edge ... ... . . . . . . . . . .. . . . . . .. . . . . . . . . . . . . . . .. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. .. . . . . . . . . . . . . . ... ... . . . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . .... . . MALLARD 

5. Dark brown feathers(> 10, small or medium-sized) on the underwing, usually along the leading 

edge and near the alula ..................................................................................................................... HYBRID 

6. Wing Black Duck-like; white subtenninal bar present on> 1 greater covert anterior to speculum; 

white terminal bar on secondaries may be present or lacking .......................................................... HYBRID 

6. Wing Black Duck-like; white subterminal bar on greater coverts lacking. White on posterior edge 

of speculum (tips of secondaries) may be complete, incomplete, or lacking ............................................... (7) 

7. Dark brown feathers (<10, small) present on underwing ................................................................. HYBRID 

7. Dark brown feathers(> 10, small to medium) present on underwing .................................... BLACK DUCK 

REPORT DOCUMENTATION PAGE 

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I 

Form approved 

OMB No. 0704-0188 , I ~·-·-·-·-·--·------·--·-·-·-·-···-.·-·----- __ ..J___·---··--····-·--·-·-

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i gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other 

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Reports, 1215 Jefferson Davis Highway. Su1te 1204, Arlington. VA 22202-4302. and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188) 

i Washington, DC 20503. 

1·1·.--AG-eNCv.usE·o-NLv-(l.~~~~----r-2~-REPoRr-oAre- ---·····-······-- -. ··r;~REPoi"l".rvPe.P.N.ooAresc_o_vE_R_E_o --. ··---· 

~-~lank) . . .......... ..... ........... . . .......................... ! .......... JYIC1~(;~~ QQQ_ .... ..... .... ..... ... .. [}:3 i()l~)~-i~~l~~~~ll~~ ~ep()l"t I 4. TITLE AND SUBTITLE f5:·FuNr)INGNuMseRs 

i 

I 

, Description and Identification of American Black Duck, Mallard, and Hybrid Wing 

I Plumage 

16. AUTHOR(S) 

I Kirby, R.E.,A. Reed, P. Dupuis, H.H. Obrecht, III, and W. J. Qm._st _________ I 

! 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESSES ~ORMING ORGANIZATION 

I

I I REPORT NUMBER 

I 

U.S. Department of the Interior 

, U.S. Geological Survey ,USGS/BRD/BSR-2000-0002 

/ Biological Resources Division 

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESSES 

U.S. Department of the Interior 

U.S. Geological Survey 

11. SUPPLEMENTARY NOTES 

11 DISTRIBUTION/AVAILABILITY STATEMENT 

Release unlimited. Available from the National Technical Information Service, 5285 Port 

R o y a I R o a d , S p r in g fie I d , VA 2 2 I 6 I ( 1 -8 0 0 -5 5 3 -6 8 4 7 o r 7 0 3 -4 8 7 -4 6 5 0 ) . A v a i I a b l e to 

registered users from the Defense Technical Information Center, Attn: Help Desk. 8725 

an Road, Suite 0944, Fort Belvoir, VA 22060-6218 (1-800-225-3842 or 703-767-9050). 

10. SPONSORING, MONITORING 

AGENCY REPORT NUMBER 

12b. DISTRIBUTION CODE 

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ABSTRACT (Maximum 200 words) 

We developed a key to identify wings of hybrids between American Black Ducks (A11as rubripes) and Mallards (A. platyrll) 'llchos). Material for 

analysis included review of historical descriptions dating from the late 1700's, older museum collections in Europe and North America, wings 

collected from hunters in North America and Great Britain, birds banded in Canada and the United States, and a flock of propagated hybrids. All 

first filial generation (F 1

) American Black Duck x Mallard hybrids were identified correctly with the key. A lower proportion of other hybrid 

cohorts (i.e., backcrosses ofF1 to parental forms (P1

)), and second and third filial generations (F", F3

, etc.) were identified. We successfully 

identified a larger portion of male than female hybrids for all hybrid progeny cohorts examined except F 1

• The new key identified 2.3 7 times 

more hybrids in the 1977 U.S. Fish and Wildlife Service Parts Collection Survey (annual determination of the species, age, and sex composition 

of the waterfowl harvest using detached wings contributed by hunters) than were identified by standard techniques. The proportion of American 

Black Duck x Mallard hybrids to the American Black Duck parental population (the ratio: hybrids/[hybrids +American Black Ducks]) may 

therefore be closer to 0.132 than 0.056, the historically reported value. The hybrid key is suggested for use from North Carolina north in the 

Atlantic Flyway and Arkansas and Tennessee north in the Mississippi Flyway (areas where other members of the Mallard group will not 

confound assessment). We provide suggestions for further research that would assist identification of wings in parts collection surveys and 

permit estimation of the proportional representation of Mallard genes in the American Black Duck gene pool. 

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14. SUBJECT TERMS (Keywords) 

American Black Duck, Anas plat;rh..J'llchos, Anas rubripes, domestic Mallard, 

hybridization, Mallard, museum, parts collection surveys, plumage, waterfowl, 

wmgs. 

15. NUMBER OF PAGES 

iv + 26 

16. PRICE CODE 

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17. SECURITY CLASSIFICATION 

OF REPORT 

Unclassified 

NSN 7540-01-280-5500 

18. SECURITY CLASSIFICATION OF 

THIS PAGE 

Unclassified 

19. SECURITY CLASSIFICATION OF 20. LIMITATION OF ABSTRACT 

ABSTRACT 

Unclassified Unlimited 

Standard Form 298 (rev. 2-89) 

Prescribed by ANSI Std. Z39-18 

298-102 

USGs-National Wetlands Research Center 

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