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Molts And Plumages
Molts and plumages of Roseate Spoonbill have been described mainly by Bent (1926); subsequent descriptions (Allen 1942, Palmer 1962, Oberholser 1974) are based primarily on Bent’s information. Within Bent’s scheme, adult (Definitive) plumage is not acquired until fourth Prebasic molt, at about 34 mo (or by third Prebasic and third Prealternate molts as interpreted by Palmer and Oberholser), and adults undergo 2 molts per year: a complete Prebasic (postnuptial) molt after breeding, and a partial Prealternate (prenuptial) molt before breeding. Bent’s assertion that adults molt twice a year was based on the assumption that adults have different breeding and winter plumages, but he acknowledged that birds he had described as “winter adults” may have been “second winter birds,” and “adults may show little seasonal change” (Bent 1926: 19). Thus, Bent’s description of 2 molts/yr, a scheme followed by Oberholser and Palmer (but not Allen), was never verified by direct observation of molt in living birds or specimens of known age. Adults and subadults develop somewhat brighter colors just prior to the breeding season. For example, Bent states that “at the second prenuptial molt, in late winter or early spring, a second nuptial plumage is assumed, including the buff tail, the carmine lesser wing-coverts and more or less of the roseate and carmine colors in the body plumage.” Bent also made similar statements regarding replacement of feathers by young birds in their first winter and subsequent spring. These statements suggest that a Prealternate molt does exist in Roseate Spoonbills, and that this molt involves the replacement of the tail, lesser wing- coverts and some unknown extent of body plumage. However, little information about molt has been verified in this species (see Palmer 1962: 534–535). Since Palmer’s descriptions were published, some new information (contradictory to some information presented by both Allen and Palmer) has been gained about the appearance of hatchlings (White et al. 1982), but nothing new has been learned about molts and plumages of older birds. Thus, most of what is known today about the species’ molts, in particular, can still be attributed to Bent’s (1926) scheme, which is best viewed as a working hypothesis awaiting confirmation (Fig. 4). Thorough studies using birds or specimens of known age and location are needed before the number, extent, and timing of the species molts, including geographic variation due to different breeding schedules, can be fully understood (see Fig. 4; Breeding: phenology, above).
The following molt and plumage descriptions follow Bent 1926 and Allen 1942, unless otherwise stated. However, because so little information is available on the timing and extent of Prealternate molt in this species, only Prebasic molts and Basic plumages will be formally described in this account. Although the sexes differ in size (see Measurements, below), they appear to be similar in plumage coloration, as in other spoonbills. For a discussion of individual variation in plumage coloration, including extent of carmine in wing, tail-coverts, mottling on back of head and neck, and extent of bare black skin, see Allen 1942 .
See Breeding: young birds, above.
See Breeding: young birds, above.
Basic I Plumage
Prebasic I molt partial; includes mantle, breast, wing-coverts, and rectrices, as indicated by plumage changes in these areas; no information on molt sequence. The Prebasic I molt may occur over extended period beginning at 4 mo and lasting until about 10 mo old, as evidenced by “progressive changes towards maturity” (Bent 1926: 18) which occur during first year of life. These changes tentatively attributed to separate Prebasic and Prealternate molts by Bent (1926), Palmer (1962) and Oberholser (1974), but confirmation of the existence of Prealternate I molt and Alternate I plumage needed.
Basic I plumage similar to Juvenal plumage, except mantle and breast become pinker, dusky-tipped primary and greater wing-coverts replaced by feathers without dusky tips, and tail becomes very pale buff. Traces of carmine occasionally appear in lesser wing-coverts and uppertail-coverts, but this is unusual (Bent 1926). Head remains feathered and white, and black tips on retained Juvenal remiges gradually become paler due to wear.
Basic II Plumage
Prebasic II molt first complete molt occurs at 14–15 mo of age. In Florida Bay, occurs mainly in Feb (Palmer 1962). No details on sequence of molt. Basic II plumage complete by about 16 mo and worn until next Prebasic molt begins, at about 20 mo. Bent and Palmer speculated that an Alternate II plumage occurred but had little information (mentioned above) with which to verify this.
Forehead, crown, cheek, and throat become bare; thin line of black skin extends from ear opening around nape and adjoins feathering on neck that may be fluffy, accentuating bare head; neck and upper breast remain white, but pink on remainder of body, wings, and tail becomes deeper in color. Little or no carmine on lesser wing-coverts.
Basic III Plumage
Prebasic III molt second complete molt; occurs at 20–21 mo of age. In Florida Bay, may occur in Aug–Sep (Palmer 1962). Plumage is worn from about 22 mo until next Prebasic molt begins, at about 32 mo of age. No details on sequence of molt. Palmer and Oberholser presumed that Basic III was the Definitive Basic plumage in some birds.
Basic III plumage superficially resembles Definitive Basic plumage but is less colorful. Compared to Basic II plumage, neck and upper breast remain white, trace of carmine streaking possible on upper breast; wings and belly deeper pink, with carmine on lesser wing-coverts; upper and undertail-coverts deep pink, with some carmine; tail buffy.
Definitive Basic Plumage
Adult (Definitive) plumage achieved by fourth Prebasic molt; occurs at about 32–33 mo of age. No details of sequence. In Florida Bay, molt may occur in Aug–Sep as birds in fresh plumage in Oct (Palmer 1962). Colors brighten compared to previous plumages. Neck, upper back, and upper breast remain white. On back of upper neck, streaks of carmine, rarely forming small mane. On upper breast and lower foreneck, a patch of stiff re-curved feathers (neck ruff), magenta-ruby to carmine. Patch of buffy yellow on side of breast by bend of wing. Lower back, lower breast, abdomen, wings bright pink. Lesser wing-coverts brilliant carmine; upper and undertail-coverts also carmine; tail is rich tawny buff, almost orange (Palmer 1962, Hancock et al. 1992).
The plumage described above typifies the appearance of birds during breeding and would be considered Definitive Alternate plumage under 2 plumages per year. Like Bent, Palmer (1962) described both Basic and Alternate plumages in adults. Palmer’s Definitive Basic (nonbreeding) plumage resembles Definitive Alternate (breeding) plumage, but with the following exceptions: the curly feathers on the breast are lacking (this change not discussed by Bent), the carmine color on the upper and undertail-coverts becomes deep pink, and the tail becomes plain buffy (Bent calls nonbreeding tail pink). Whether these changes occur in the wild is uncertain. Confirmation and description of changes would help document any differences in summer range and seasonal movement of adults versus younger birds (Robertson et al. 1983, Bjork and Powell 1996; see Migration).
Melanism has been reported (Pearson 1921).
Carotenoid pigments in plumage derived from diet but deposition of pigment (amount, location) associated with age (Brush 1990). Carotenoid pigments from flight and body feathers of adults primarily are canthaxanthin and astaxanthin (Fox 1962). Canthaxanthin is also the chief carotenoid deposited in feathers of several species of flamingos (American Flamingo [Phoenicopterus ruber], Andean Flamingo [P. jamesi]; Chilean Flamingo [P. chilensis]) and Scarlet Ibis.
In Basic I plumage, bill dirty yellow to dullish green; in Basic II, dull greenish or bluish; in Basic III, surface rough and greenish blackish as in adults. In Definitive Basic plumage, hornlike excrescences at base of upper mandible and various colors: grayish green to grayish tan, with mottled areas of green, black, and yellow.
In Basic I plumage, possibly amber; probably same as “light orange red” in Florida (JVD). In Basic II plumage, reported as amber; but red in Florida, different from previous color (JVD). In Basic III plumage, reddish. In Definitive Basic plumage, cherry red to scarlet.
Bare Skin On Head
Head feathered until Basic II plumage attained, when it becomes bare; Basic II head blue-green; thin black line adjoins neck-feathering. In Basic III plumage, greenish. In Definitive Basic plumage, pale or apple green to golden buff; thick area of black skin most prominent in this plumage, sometimes extending into V-shape down back of neck, but varies among individuals. Courting captives develop bright saffron-orange gular sacs and orange rings around eyes (Hancock et al. 1992). Orange color observed in Florida for only short period during breeding season (A. Sprunt IV in Hancock et al. 1992); also observed in South America.
Legs And Feet
In Basic I plumage, reported as dark, but legs of living birds appear flesh-colored (feet not seen; JVD). In Basic II plumage, reported as more flesh-colored, but legs dark red in Florida birds (feet not seen; JVD). In Basic III plumage, legs dull red, feet blackish. In Definitive Basic plumage, legs magenta-ruby, feet blackish; some black at tibiotarsal joint and down back of tarsus.