IN THE SCOPE
Plumage Progression in Male
Northern Shovelers
Tony Leukering
I suspect that because the bill of Northern Shoveler is so distinctive, few birders look beyond the bill to the amazing variety of appearances that male Northern Shovelers present. Much of this variety is due to the species’ molt strategy, one that is very different
from that of most of the other dabbling ducks that winter regularly
in Colorado. Unlike Gadwall, Mallard, Northern Pintail, and most
other dabbling-duck species, male Northern Shovelers do not attain
full basic plumage before arriving on the wintering grounds. Instead,
their prebasic molt is extended through much of the winter.
In Colorado and elsewhere in the northern half of the Lower 48
United States, Blue-winged Teal is of very rare occurrence during
winter (December-February), except at some coastal locations. Many
birders are stymied by winter dabbling ducks showing a white facial
crescent at a time when Blue-winged Teal is rare. As the appearance
of male Northern Shoveler can mimic that of Blue-winged Teal and
because the species shows incredible diversity of appearance from fall
through winter, this essay treats the plumage development of male
Northern Shoveler. It is meant to be read with reference to the pictures presented in Figs. 1–3 (p. 61) and Figs. 4–6 (back cover).
As some basic understanding of terms is necessary for full understanding of the meat of this essay, I provide a very brief explanation
of general molt and plumage strategies in male Northern Shoveler
and other dabbling-duck species. Molt progression and timing in
females are different from those of males of the same species, and,
unless specifically noted, the text should be assumed to refer only to
male strategies.
Molt Location and Timing
In this essay, I follow Pyle (2005, 2013) in considering the socalled eclipse plumage to be an alternate plumage and the bright
plumage a basic plumage, and I utilize plumage and molt terms of
Howell et al. (2003) and Pyle (2008). Adult males of most ABAarea dabbling-duck species initiate molt out of basic plumage (termed
“breeding plumage” by many) in late spring or early summer (about
the time that females are on nests) into a more cryptic plumage,
sometimes called “eclipse” plumage, for the period in which they replace their flight feathers and become flightless. Many males move
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to particularly favored molting grounds, which may be close to the
individuals’ breeding sites or quite distant. There, they replace their
bright basic plumage with a cryptic alternate plumage and then instigate wing molt. When the flight-feather aspect of the prebasic molt
nears completion, most species’ males then initiate the prebasic body
molt and, essentially, complete it prior to fall migration.
Northern Shoveler (and Blue-winged and Cinnamon Teal) modifies this general dabbling-duck strategy by delaying the onset and,
particularly, the completion of the body-plumage aspect of this molt.
The speed at which this species attains basic plumage is very slow,
such that it can be initiated on the molting/breeding grounds, continued on the winter grounds, and completed on spring migration or,
even, back on the breeding grounds. Pyle (2008) notes the duration
of this molt in adult male Northern Shovelers as July through March!
However, molt speed is also individually variable, and as early as December, one can see at the same place and time adult male Northern
Shovelers in nearly full alternate plumage (Fig. 5) alongside others in
nearly full basic plumage (Fig. 6).
Juvenile males attain flight in a very female-like plumage and conduct one or two preformative molts before attaining male-like plumage in their first spring (Pyle 2008). In Northern Shoveler, the first
of two preformative molts is often (usually?) quite limited, while the
second is significant, replacing most or all of the body plumage, but
few, if any, flight feathers. During this time, their bills transition from
the dull “slaty-orange” (Pyle 2008), olive-tinged orange, or orangetinged olive (pers. obs.) to the black typical of older males. Juvenile
males may not complete this molt until sometime in April. Note that
any Northern Shoveler with a black or extensively black bill is a male,
even if entirely in a female-like plumage as late as February (Fig. 2).
Ageing Northern Shovelers
The eyes of both sexes of Northern Shoveler transition from darker
to lighter during their first year, with the eye color of juvenile males being a fairly dark olive, that of juvenile females being dark brown, that
of full adult males being a clear, bright yellow, and that of adult females
ranging from amber-yellow to orange-brown. The speed at which this
change takes place is individually variable, with some first-year males
attaining essentially adult eye color by February or possibly even January (pers. obs.). What little solid data I have suggests that eye-color
change in males is more rapid than that in females, and many young
females may be diagnosable as such by eye color well into the summer
of their second calendar year, though certainty is hampered by the
variety of eye color displayed by apparently adult females.
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Fig. 1. The dark brown eye and mostly orange bill suggest that this Northern Shoveler is probably a female,
and the date of the picture just about confirms that suggestion, as even the tardiest of molting immature
males (see Fig. 2) would have paler eyes and a darker bill. The arrow points to the longest of the bird’s four
tertials (two above the indicated tertial, one below). All sport the typical female pattern, with a broad pale
fringe all around. A male’s juvenal (= first basic) tertials are identical in pattern. Pima County, Arizona,
26 February 2011. Photograph by Christopher L. Wood
Fig. 2. This Northern Shoveler would be identified as a female by many birders, particularly in February,
when the picture was taken. However, the black bill confirms this bird as a male. The innermost tertial (right
arrow) is a juvenal feather and sports the female-like pattern noted in Fig. 1. However, the other tertials are
more male-like in pattern, particularly the innermost (left arrow), which has the typical male pattern with a
wide, white shaftstreak/trailing edge and no pale fringe on the leading edge. The olive cast to the eye confirms
what the presence of two patterns of tertials suggest, that it is a first-cycle bird finally initiating its molt into
male plumage. Earlier in the life of this bird, the bill would more closely mimic that of an adult female, and
sexing it in the field would be quite difficult. Near Jamnagar, India, 4 February 2012. Photograph by
Neha and Chittaranjan Desai
Fig. 3. The grayish head with obvious but diffuse white crescent in front of the eyes, the pattern of the tertials
(see Figs. 1–2), and the bits of cinnamon-rufous color coming in on the sides identify these Northern Shovelers as males. The left bird’s extensive black on the bill is an additional sex-identifying character. They can
be identified as immatures using a number of features visible here, particularly the olive cast to the eyes and
the extensive pale coloration on the bills. The right bird’s left outermost rectrix (tail feather) is very pointed
and worn and has a sizable patch of brown. The longest side feathers (the ones that extend up and cover the
base of the innermost tertial) are pointed and have obvious pale chevron-shaped internal markings. The left
bird has replaced its longest side feathers in its first preformative molt with adult-shaped feathers that lack
internal pale markings; these will be replaced by adult-male-type feathers as its second preformative molt
continues. Brazoria National Wildlife Refuge, Brazoria County, TX, 18 November 2012. Photograph
by Tony Leukering
Fig. 4 (back cover). This Northern Shoveler’s bright yellow eye confirms it as an adult male. As the photo
was taken in July, we know that the bird is in full (or nearly full) alternate plumage. On this captive
individual, note the diffuse loral crescent, the olive- and orange-shaded bill, the extensively white tail with
the outermost feathers being entirely white, and the round-tipped longest side feathers lacking pale internal
markings. Oleron, France, 18 July 2005. Photograph by Philippe Boissel
Fig. 5 (back cover). These birds’ extensively black bills easily identify them as males. The right bird’s allblack bill and clear yellow eye in November strongly suggest that it is an adult, as do the wide, metallic-green
tertials with somewhat blunt tips and wide, white trailing edges, and the complete lack of any obvious juvenal
plumage. The left bird is a bit more problematic, as it has the clear yellow eye and wide, green tertials of an
adult. However, its bill has some paler areas that might suggest immaturity, but which are also typical of
adults earlier in the plumage progression (see Fig. 4). This bird also has one long side feather that is pointed
and sporting pale internal markings, a character typical of juvenal plumage, but it is the only such feather
apparent on the bird. Considering the date and the eye color, this bird is probably an adult, but it illustrates
the difficulty in definitively determining age of male Northern Shovelers on which more wing characters (e.
g., lesser-coverts color) cannot be assessed. Merritt Island National Wildlife Refuge, Brevard County, FL,
20 November 2012. Photograph by Larry Sullivan/Gatorphotography
Fig. 6 (back cover). This male in nearly complete basic plumage would be very difficult to age with certainty
in March without better views of its tail and open wings. However, in December, this bird represents the
rapid end of plumage progression in males of the species, so it can be comfortably identified as an adult.
As this individual’s prebasic molt continues, it will replace the remaining non-green head feathers and the
chest and side feathers that have internal markings. Belmar, Monmouth County, NJ, 3 December 2011.
Photograph by Jessica Kirste
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Fig. 1. Female Northern Shoveler, Pima
County, Arizona, 26
February 2011. Photograph by Christopher L. Wood
Fig. 2. Firstcycle male
Northern Shoveler. Near Jamnagar, India, 4
February 2012.
Photograph by
Neha and Chittaranjan Desai
Fig. 3. Firstcycle male
Northern Shovelers, Brazoria
National Wildlife
Refuge, Brazoria
County, TX, 18
November 2012.
Photograph by
Tony Leukering
Colorado Birds January 2013 Vol. 47 No. 1
61
Additionally, as in most other duck species, worn first-year Northern Shovelers can be aged by the paleness and wear state of their
tails, as these become ragged and bleached by spring (when the feathers are approaching a year in age), while those of adults are much
less worn, being composed of feathers that are a few months younger
in many cases. However, tail wear can be difficult to ascertain with
certainty in Northern Shovelers, due to the fact that, like Mallard
but unlike any other ABA-area dabbling-duck species, their tails are
extensively white to begin with.
The upperside lesser and median secondary coverts of adult males
are solidly powder blue, creating an extensive, unrelieved, highlycontrasting patch of that color on the leading edge of the wing. These
feathers on first-year males are a dusky-washed dull blue, creating a
patch that contrasts less with the rest of the wing. The presence of
juvenile-type feathers can assist in correct ageing, with particularly
useful feathers being the side feathers adjacent to the wing (pointed
in juveniles, with pale chevron-shaped internal markings; rounded in
adults, generally lacking internal markings) and tertials (dull black
in juveniles, with limited whitish stripe and very pointed tip; metallic greenish in adults, with wide, white shaft streak and blunter tip).
Note that first-year males can be differentiated from all females by
the shape and pattern of their tertials (Figs. 1–3).
Confusion with Blue-winged Teal
From July deep into winter, male Northern Shovelers with white
loral crescents of greater or lesser extent and definition can readily
be found among large numbers of the species in Colorado, and the
feature is illustrated to a variable extent in a number of recent ABAarea field guides. While the text of Pyle (2008) seems to suggest that
it is immatures that sport such a feature, Sibley (2000) notes it as
a facet of plumage of adult males in fall, and National Geographic
Society (2008) describes it as a characteristic of fall males in general.
In fact, this crescent is a general feature of male Northern Shovelers
in plumages other than definitive basic (bright adult plumage). Some
of the extent and variation of male Northern Shoveler loral crescents
can be seen in Figs. 3–5.
The South Platte River in Southern Adams County
This locale is, perhaps, the best place in the extensive range of
Northern Shoveler to study the nearly-infinite variation in appearance of males of the species, for four reasons: 1) The species occurs
here in large numbers for well over half the year; 2) paved walking
trails along one or both banks allow for easy access to the river on
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which these birds loaf and forage; 3) the river is not at all wide in this
stretch; and 4) the birds get accustomed to foot and bicycle traffic,
thus allowing fairly close approach.
Acknowledgments
I greatly appreciate the review of a previous draft of this essay by Jessie
Barry.
Literature Cited
Howell, S. N. G., C. Corben, P. Pyle, and D. I. Rogers. 2003. The first basic
problem: A review of molt and plumage homologies. Condor 105:635653.
National Geographic Society. 2011. Field Guide to the Birds of North America, 6th ed. National Geographic Society, Washington DC.
Pyle, P. 2005. Molts and plumages of ducks (Anatinae). Waterbirds 28:208219.
Pyle, P. 2008. Identification Guide to North American Birds, part II. Slate
Creek Press, Bolinas, CA.
Pyle, P. 2013. Molt homologies in ducks and other birds: A response to
Hawkins (2011) and further thoughts on molt terminology in ducks.
Waterbirds in press.
Sibley, D. A. 2000. The Sibley Guide to Birds. Alfred A. Knopf, New York.
Tony Leukering, 102 Delaware Avenue, Villas, NJ 08251, [email protected]
Colorado Birds January 2013 Vol. 47 No. 1
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Fig. 4. Adult male Northern Shoveler in
alternate (“eclipse”) plumage, Oleron,
France, 18 July 2005. Photograph by
Philippe Boissel
Fig. 5. Male Northern Shovelers, Merritt
Island National Wildlife Refuge, Brevard
County, FL, 20 November 2012. Photograph by Larry Sullivan/Gatorphotography
Fig. 6. Adult male Northern Shoveler, Belmar, Monmouth County, NJ, 3 December
2011. Photograph by Jessica Kirste
In the Scope: Northern Shoveler . . . 58
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