Plumages, Molts, and Structure

The Northern Flicker (Colaptes auratus) has 10 functional primaries (numbered distally, from innermost p1 to outermost p10, with the p10 reduced in length), 10 secondaries (numbered proximally, from innermost s1 to outermost s10, and including 3 tertials, s8–s10), and 12 rectrices (numbered distally, from innermost r1 to outermost r6, one on each side of the tail, the r6 pair reduced in length). The following pertains to both the Yellow-shafted Flicker (C. a. auratus) and Red-shafted Flicker (C. a. cafer) subspecies groups in North America (8 Ridgway, R. (1914). The birds of North and Middle America. Bulletin of the United States National Museum 50, part VI. Close , 9 Bent, A. C. (1939). Life histories of North American woodpeckers. United States National Museum Bulletin 174, Smithsonian Institution, Washington, DC, USA. Close , 10 Oberholser, H. C. (1974). The Bird Life of Texas. University of Texas Press, Austin, Texas, USA. Close , 11 Short, L. L. (1982). Woodpeckers of the World. Monograph Series 4, Delaware Museum of Natural History, Greenville, DE, USA. Close , 12 Shunk, S. A. (2016). Peterson Reference Guide to Woodpeckers of North America. Houghton Mifflin Harcourt Publishing Company, New York, NY, USA. Close ) ; see Geographic Variation for appearance variation within each of these groups, variation among intergrades between the groups, and variation among subspecies of Mexico, Central America, and the Caribbean. For age-related descriptions of molt patterns, see Pyle and Howell (13 Pyle, P., and S. N. G. Howell (1995). Flight-feather molt patterns and age in North American woodpeckers. Journal of Field Ornithology 66(4):564–581. Close ) and Pyle (14 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ). Sexes differ in all plumages; definitive appearance typically assumed at Third Basic Plumage but sometimes at Fourth Basic Plumage.

Natal Down

Hatchlings altricial and naked; no down develops in woodpeckers including the Northern Flicker (9 Bent, A. C. (1939). Life histories of North American woodpeckers. United States National Museum Bulletin 174, Smithsonian Institution, Washington, DC, USA. Close , 15 Test, F. (1945). Molt in flight feathers of flickers. Condor 47:63–72. Close , 11 Short, L. L. (1982). Woodpeckers of the World. Monograph Series 4, Delaware Museum of Natural History, Greenville, DE, USA. Close ).

Juvenile (First Basic) Plumage

Present primarily May–August.

Yellow-shafted Flicker

Similar to Definitive Basic Plumage except colors duller and plumage softer and looser (9 Bent, A. C. (1939). Life histories of North American woodpeckers. United States National Museum Bulletin 174, Smithsonian Institution, Washington, DC, USA. Close ); crown variably suffused with red (especially in males); red nuchal patch somewhat broader; black and tan bars across feathers of upperparts and upperwing coverts broader and less distinct; uppertail coverts with more-extensive black bars, giving them a darker appearance in comparison to boldly contrasting black and off-white bars in adult; black tips to rectrices duller and less sharply defined (see Figure 130 in 14 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ); tan portions of head and neck more grayish; shaft color of remiges and rectrices duller; outer primary (p10) rounded and larger (tip usually > 17 mm from tip of primary coverts versus usually < 16 mm in basic plumages); black crescent on breast smaller, especially laterally; breast and belly paler, duller, and with larger spots. The malar (moustachial) stripe can be present in both sexes, but is sootier, less black (9 Bent, A. C. (1939). Life histories of North American woodpeckers. United States National Museum Bulletin 174, Smithsonian Institution, Washington, DC, USA. Close ) and can be less distinct to lacking in female (8 Ridgway, R. (1914). The birds of North and Middle America. Bulletin of the United States National Museum 50, part VI. Close ); reddish malar stripe in Yellow-shafted Flicker mentioned by Pyle (16 Pyle, P. (1997). Identification Guide to North American Birds. Part I. Slate Creek Press, Bolinas, CA, USA. Close ) in error (KLW) and probably based on an intergrade with Red-shafted Flicker or a pigment anomaly (14 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ; P. Pyle, personal communication); intergrade nestlings can have malar stripes with both colors (as in some intergrade adults). Some females and males in Juvenile Plumage may not be separable from a distance; although in the hand, males in Juvenile Plumage tend to have more red suffusion in crown (often lacking in females) and a more-distinct and darker (blacker) malar stripe.

Red-shafted Flicker

Juvenile similar to Red-shafted Flicker in Definitive Basic Plumage except most of differences mentioned above apply; crown with less red suffusion than in Yellow-shafted Flicker (male with little or none, female usually without red); sexes easily distinguished by the red malar stripe which is absent in most femalesand present in males; rarely, females may display pale salmon-pink malar color (KLW).

The innermost primaries (p1 and p2) are reportedly abbreviated (5–20 mm in length) in woodpeckers in Juvenile Plumage (17 Chapin, J. P. (1921). The abbreviated inner primaries of nestling woodpeckers. Auk 38(4):531–552. Close , 18 Sibley, C. G. (1957). The abbreviated inner primaries of nestling woodpeckers. Auk 74(1):102–103. Close , 19 Koenig, W. D., M. T. Stanback, and J. Haydock (2006). Abbreviated inner primaries: a sex-linked dimorphism in the Acorn Woodpecker. Journal of Field Ornithology 77(2):157–162. Close ), but description and length of these feathers in the Northern Flicker is needed; they are usually replaced before the nestling fledges from the nest cavity. It is possible that these feathers are not inherently short but drop during the Preformative Molt before being fully grown, thus being at various lengths when replaced (P. Pyle, personal communication).

Formative Plumage

"First Basic" or "Basic I" plumage of Humphrey and Parkes (20 Humphrey, P. S., and K. C. Parkes (1959). An approach to the study of molts and plumages. The Auk 76(1):1–31. Close ) and some subsequent authors; see revision by Howell et al. (21 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 105:635–653. Close ). Present primarily August–July. Similar to respective Definitive Basic Plumages by subspecies group and sex except juvenile primary coverts are retained, uniform in wear, with paler shaft colors, and becoming worn and brown by winter or spring; back feathers and replaced formative inner upperwing coverts deeper buff or brown with distinct black bars, often contrasting with retained juvenile outer greater coverts with paler (more faded) and broader more triangular brown bars and less-distinct and grayish dark bars (see Figure 131 in 14 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ); secondaries uniform in wear, with tertials becoming very worn by spring, or (occasionally) 1–3 tertials replaced and contrastingly fresh (13 Pyle, P., and S. N. G. Howell (1995). Flight-feather molt patterns and age in North American woodpeckers. Journal of Field Ornithology 66(4):564–581. Close ; Figure 119A–B in 14 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ).

Second Basic Plumage

Present primarily September–August. Similar to respective Definitive Basic Plumages by subspecies group and sex except some juvenile primary coverts and (sometimes) secondaries retained, brown, and very abraded compared to replaced feathers. Retained primary coverts include 4–7 consecutive medial feathers (among those corresponding to p4–p9), brown and very abraded, contrasting with 1–5 consecutive replaced distal feathers (among those corresponding to p5–p10), forming paler panel or badge on upperwing. Juvenile secondaries, when present, occur in block of 1–4 feathers among s1–s5. See Pyle and Howell (13 Pyle, P., and S. N. G. Howell (1995). Flight-feather molt patterns and age in North American woodpeckers. Journal of Field Ornithology 66(4):564–581. Close ) and Figure 119C in Pyle (14 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ) for details.

Third Basic Plumage

Apparently identifiable in some Northern Flickers (see Third Prebasic Molt); present primarily September–August. Similar to respective Definitive Basic Plumages by subspecies group and sex, and indistinguishable for most birds, but occasional individuals are identified by having 1–2 adjacent juvenile primary coverts retained, among those corresponding to p5–p7, along with 2 generations of basic coverts found proximal and distal to these feathers (cf. 22 Siegel, R. B., M. W. Tingley, R. L. Wilkerson, C. A. Howell, M. Johnson, and P. Pyle (2016). Age structure of Black-backed Woodpecker populations in burned forests. Auk 133(1):69–78. Close ), as shown in Figure 5F in Pyle and Howell (13 Pyle, P., and S. N. G. Howell (1995). Flight-feather molt patterns and age in North American woodpeckers. Journal of Field Ornithology 66(4):564–581. Close ) and Figure 119D in Pyle (14 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ).

Definitive Basic Plumage

Present primarily September–August. Color enumeration corresponds to Kornerup and Wanscher (23 Kornerup, A., and J. H. Wanscher (1967). Methuen Handbook of Colour. Second edition. Metheun, London, United Kingdom. Close ).

Yellow-shafted Flicker

Female. Crown gray (4D–E3), sometimes tinged olive; nape with narrow red (10A8) patch; back barred with blackish brown (8F2) and buffy brown (5D3–4); rump white, usually unmarked; uppertail coverts white with black bars, chevrons, or U-shaped marks; upper surfaces of rectrices blackish brown, distinctly tipped black, edged with buffy white in fresh plumage, and often with white or buffy bars on outer web of outer feathers and inner web of central pair; undersurfaces of rectrices yellow (3A7) with black tips. Upperwing secondary coverts and tertials similar to back feathers; primary coverts and primaries brownish with yellow (3A7) shafts and inner webs at bases on undersurfaces; uppersurfaces of secondaries except tertials brownish with yellow shafts and pale brown scalloping (circular spots) along inner and outer webs becoming larger proximally within the tract; undersurfaces of secondaries with yellow edges to inner webs. Sides of head and auriculars fawn-tan (6C4–5), the loral area and area above eye often tinged buffy cinnamon (6D6). Chin and throat pale tan (6C–D3–4); upper breast with distinct crescent-shaped black patch; remaining underparts white tinged weak to strong buffy yellow (4–5B3) and marked with rounded black spots, becoming elongate bar-spots on flanks and the breast markings occasionally reduced to sparse spots or streak-spots; undertail coverts with elongate, often cup-shaped, bars; underwing coverts pale to deep yellow, sometimes slightly tinged orange proximally.

Male. Similar to Definitive Basic female, but distinct black malar (moustachial) stripe present, extending from base of bill to side of neck.

Red-shafted Flicker

Female and Male. Similar to respective sexes of Yellow-shafted Flicker in Definitive Basic Plumage except crown various shades of brown; nape without red patch; shafts and undersurfaces of flight feathers salmon (7A–B6–7); auriculars, chin, and throat gray (1D1); malar stripe red (10A8); breast, belly, and underwing coverts white, often with pinkish cast (6B2–3); differences summarized in Table 1. Note that intergrades between subspecies groups can show various and mixed combinations of character differences (see Geographic Variation).

In both sexes, Definitive Basic Plumage is separated from Formative Plumage and Second Basic Plumage by having uniformly basic and/or mixed generations of basic feathers among secondaries (1–4 feathers among s1–s8) and primary coverts. When mixed, older feathers usually do not contrast as severely with replaced feathers as in Second and Third Basic Plumages, the feathers usually do not occur in blocks, and they often occur asymmetrically between wings (13 Pyle, P., and S. N. G. Howell (1995). Flight-feather molt patterns and age in North American woodpeckers. Journal of Field Ornithology 66(4):564–581. Close , 14 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ). Various positions of retained and replaced secondaries and primary coverts should enable minimum age determination up to four years or more, but details need to be worked out. In some cases basic feathers may be retained for two or more years and become quite abraded, but their position within the tracts, not corresponding with those of retained juvenile feathers, will confirm Definitive Basic Plumage.

Flight Feather Pigmentation

The striking color in remiges of Yellow-shafted and Red-shafted flickers are derived from carotenoids that the birds must obtain from their diet but which may be modified by metabolic processes (24 Hudon, J., K. L. Wiebe, E. Pini, and R. Stradi (2015). Plumage pigment differences underlying the yellow-red differentiation in the Northern Flicker (Colaptes auratus). Comparative Biochemistry and Physiology B-Biochemistry & Molecular Biology 183:1–10. Close ). The yellow pigments are mainly lutein, zeaxanthin, and β-cryptoxanthin (25 Stradi, R. (1998). The Colour of Flight: Carotenoids in Bird Plumage. Solei Press, Milan, Italy. Close ); whereas, the red shafts of cafer contain oxygenated products of the yellow pigments including astaxanthin, α-doradexanthin, and canthaxanthin. The red of the nuchal and malar patches are primarily astaxanthin. The degree of oxidation of the molecules positively correlates with the degree of redness (24 Hudon, J., K. L. Wiebe, E. Pini, and R. Stradi (2015). Plumage pigment differences underlying the yellow-red differentiation in the Northern Flicker (Colaptes auratus). Comparative Biochemistry and Physiology B-Biochemistry & Molecular Biology 183:1–10. Close ). Within Red-shafted Flicker, the color deepens with age for males, but this is not detectable by human eye (26 Wiebe, K. L., and G. R. Bortolotti (2002). Variation in carotenoid-based color in Northern Flickers in a hybrid zone. Wilson Bulletin 114(3):393–400. Close ). The orange remiges of intergrades, in addition to the yellow and red pigment molecules of auratus and cafer, have unique molecules that are incompletely oxidized and may be the result of disruptions along the normal pigment modification pathways (27 Hudon, J., K. L. Wiebe, and R. Stradi (2021). Disruptions of feather carotenoid pigmentation in a subset of hybrid northern flickers (Colaptes auratus) may be linked to genetic incompatibilities. Comparative Physiology and Biochemistry, Part B 251:110510 Close ).

"Odd" yellow or pale feathers within the otherwise red remiges of cafer individuals appear to be replacement feathers regrown outside the normal molting period (26 Wiebe, K. L., and G. R. Bortolotti (2002). Variation in carotenoid-based color in Northern Flickers in a hybrid zone. Wilson Bulletin 114(3):393–400. Close ). In Yellow-shafted flicker, anomalous red feathers can also result from rhodoxanthin, ingested from berries of nonnative bush honeysuckles (Lonicera spp.), which interferes with the production of lutein (28 Hudon, J., R. J. Driver, N. H. Rice, T. L. Lloyd-Evans, J. A. Craves, and D. P. Shustack (2017). Diet explains red flight feathers in Yellow-shafted Flickers in eastern North America. Auk 134(1):22–33. Close ). The activity of the enzymes that regulate color are controlled by several genes including CYP2J19 (29 Aguillon, S. M., J. Walsh, and I. J. Lovette (2021). Extensive hybridization reveals multiple coloration genes underlying a complex plumage phenotype. Proceedings of the Royal Society B 288:20201805. Close ) and efforts to clarity the Mendelian inheritance and dominance relationship of the alleles that control plumage coloration are ongoing.

Consistent with the hypothesis that carotenoid pigmentation is a signal of health or body condition in birds, nestlings with higher body mass had higher carotenoid chroma (i.e., more intense pigment saturation) in their flight feathers (30 Musgrove, A. B., and K. L. Wiebe (2015). Condition-dependent expression of carotenoid- and melanin-based plumage colour of northern flicker nestlings revealed by manipulation of brood size. Journal of Avian Biology 47:176–184. Close ). Furthermore, healthy male nestlings with strong immune responses had more color intensity in flight feathers (31 Musgrove, A. B., K. L. Wiebe, C. E. Parker, and M. Romero (2017). Brood size manipulations reveal relationships among physiological performance, body condition and plumage colour in Northern Flicker Colaptes auratus nestlings. Ibis 159:600–610. Close ). Female nestlings have overall lower carotenoid deposition (i.e., more reflective feathers) than do males (30 Musgrove, A. B., and K. L. Wiebe (2015). Condition-dependent expression of carotenoid- and melanin-based plumage colour of northern flicker nestlings revealed by manipulation of brood size. Journal of Avian Biology 47:176–184. Close ).

Melanin Pigmentation

The size of black (melanin) plumage patches or their hue may indicate the health or vigor of birds although the physiological mechanisms are not yet fully understood. In nestlings, experimental manipulation of nutritional availability revealed that the size of the black breast spots was positively correlated with nestling mass and with the intensity of the carotenoid color of their flight feathers (30 Musgrove, A. B., and K. L. Wiebe (2015). Condition-dependent expression of carotenoid- and melanin-based plumage colour of northern flicker nestlings revealed by manipulation of brood size. Journal of Avian Biology 47:176–184. Close ). Female nestlings on average had larger breast spots than males, but the size of a nestling's spots was not correlated with the size of either the mother's or the father's spots (30 Musgrove, A. B., and K. L. Wiebe (2015). Condition-dependent expression of carotenoid- and melanin-based plumage colour of northern flicker nestlings revealed by manipulation of brood size. Journal of Avian Biology 47:176–184. Close ). In adults, the width of the black terminal tail band did not differ between the sexes, but it increased with age for both males and females (32 Wiebe, K. L., and M. N. Vitousek (2015). Melanin plumage ornaments in both sexes of Northern Flickers are associated with body condition and predict reproductive output independent of age. Auk 132:507–517. Close ). The size of breast spots increased with age for females but not males, whereas the length of the malar stripe increased with age and body size for males (32 Wiebe, K. L., and M. N. Vitousek (2015). Melanin plumage ornaments in both sexes of Northern Flickers are associated with body condition and predict reproductive output independent of age. Auk 132:507–517. Close ). The chroma or "blackness" of the chest bib was greater on average in males and in old females compared to yearling (Formative) females, and it was correlated with body condition in yearling females. With age statistically controlled for, females with darker bib chroma had earlier laying dates, larger clutches and more fledglings. There was a tendency that the number of fledglings was positively correlated with the width of the male's terminal tail band, but not with the length of his malar stripe (32 Wiebe, K. L., and M. N. Vitousek (2015). Melanin plumage ornaments in both sexes of Northern Flickers are associated with body condition and predict reproductive output independent of age. Auk 132:507–517. Close ). With age controlled for, there was further assortative pairing according to chest bib blackness and terminal tail band width, suggesting that these could be used as cues of mate quality (32 Wiebe, K. L., and M. N. Vitousek (2015). Melanin plumage ornaments in both sexes of Northern Flickers are associated with body condition and predict reproductive output independent of age. Auk 132:507–517. Close ).

Molt and plumage terminology follows Humphrey and Parkes (20 Humphrey, P. S., and K. C. Parkes (1959). An approach to the study of molts and plumages. The Auk 76(1):1–31. Close ), as modified by Howell et al. (21 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 105:635–653. Close ). The Northern Flicker exhibits a Complex Basic Strategy (cf. 33 Howell, S. N. G. (2010). Peterson Reference Guide to Molt in North American Birds. Houghton Mifflin Harcourt, Boston, Massachusetts, USA. Close ), including incomplete to complete prebasic molts and an incomplete preformative molt, but no prealternate molts (34 Stone, W. (1896). The molting of birds with special reference to the plumages of smaller land birds of eastern North America. Proceedings of the Academy of Natural Sciences of Philadelphia 43:108–164. Close , 15 Test, F. (1945). Molt in flight feathers of flickers. Condor 47:63–72. Close , 10 Oberholser, H. C. (1974). The Bird Life of Texas. University of Texas Press, Austin, Texas, USA. Close , 13 Pyle, P., and S. N. G. Howell (1995). Flight-feather molt patterns and age in North American woodpeckers. Journal of Field Ornithology 66(4):564–581. Close , 14 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ; Figure 1). No geographic or sex-specific variation in molt strategies has been reported within North America (15 Test, F. (1945). Molt in flight feathers of flickers. Condor 47:63–72. Close ), although some variation in average timing and extent likely occurs through Mexico and Central America in response to variable environmental and migratory constraints, day-length regimes, and breeding seasonality.

Prejuvenile (First Prebasic) Molt

Complete, primarily April–July, in the nest. By day 6, feather tracts first appear in hatchlings along posterior edge of alar tract, on caudal tract, and along anterior and midbody regions of dorsal tract; by days 7–8, flight feathers appear as pin feathers; by days 10–11, feather vanes begin to erupt from tips of flight-feather shafts; by days 12–15, contour feathers dramatically more conspicuous; by day 17, vanes of emerging flight feathers begin to unfold laterally, vanes of tail feathers extend 18–21 mm from shafts; by day 23, crown apterium closed to an inconspicuous furrow, vanes of tail feathers extend approximately 25 mm. By fledging at days 24–27, body feathers completely grown; primaries and rectrices usually complete growth within 5–10 d of fledging, by which time Preformative Molt (below) of inner primaries has commenced. See also Young Birds: Growth and Development.

Preformative Molt

"First Prebasic" or "Prebasic I" molt of Humphrey and Parkes (20 Humphrey, P. S., and K. C. Parkes (1959). An approach to the study of molts and plumages. The Auk 76(1):1–31. Close ), and some subsequent authors; see revision by Howell et al. (21 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 105:635–653. Close ). Incomplete, primarily June–October (Figure 1), on or near breeding grounds. As in other woodpeckers, the Preformative Molt likely begins in the nest, before fledging, with replacement of the innermost two primaries (p1–p2; see Juvenile Plumage) and perhaps some other feathers (study needed). Preformative Molt includes most or all body feathers, some to most inner, lesser, and medium upperwing coverts, no to most (occasionally all?) proximal greater coverts, occasionally (in approximately 8% of individuals) 1–3 tertials (among s8–s10), and all primaries and rectrices, but no primary coverts or other distal secondaries, an unusual Preformative Molt pattern unique to woodpeckers (13 Pyle, P., and S. N. G. Howell (1995). Flight-feather molt patterns and age in North American woodpeckers. Journal of Field Ornithology 66(4):564–581. Close ). Primaries are replaced distally (p1 to p10) and secondaries are usually replaced bilaterally from the second tertial (s9). Pairwise molt of rectrices begins when primaries are about half molted; small, outer rectrix (r6) usually molted first, but this is highly variable; large rectrices invariably molt in order r2–r3–r4–r5–r1 (15 Test, F. (1945). Molt in flight feathers of flickers. Condor 47:63–72. Close ), a sequence that enables the central rectrices, critical for stability on vertical tree trunks, to be replaced when other rectrices are fresher and stronger (see image under Plumages: Flight Feather Pigmentation).

Second Prebasic Molt

Incomplete, primarily June–October, occurring on or near the breeding territory. Includes all body feathers, secondary coverts, primaries, and rectrices, 1–2 inner and 1–5 outer primary coverts, and 6 to all (in approximately 75% of individuals) secondaries; 3–8 juvenile primary coverts are retained in the center of the tract, and 1–4 secondaries are sometimes retained in a block among s1–s5, usually symmetrically in both wings. Similar in extent to Definitive Prebasic Molt, but replacement of juvenile secondaries and primary coverts occur in fixed sequence: juvenile outer primary coverts are replaced distally from innermost coverts and proximally from the outermost covert, such that the last feather replaced usually is that coreresponding to p6, and juvenile secondaries are replaced distally from s1 and proximally from the tertials, such that the last feather replaced is usually s3. Sequence of primary and rectrix replacement as in Preformative Molt. See Pyle and Howell (13 Pyle, P., and S. N. G. Howell (1995). Flight-feather molt patterns and age in North American woodpeckers. Journal of Field Ornithology 66(4):564–581. Close ) and Pyle (14 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ) for details.

Third Prebasic Molt

Incomplete to complete, primarily June–October, occurring on or near the breeding territory. Some individuals in other woodpecker species continue to retain 1–2 juvenile primary coverts among the 4th to 6th coverts from the outside, corresponding to p5–p7, following the Third Prebasic Molt (22 Siegel, R. B., M. W. Tingley, R. L. Wilkerson, C. A. Howell, M. Johnson, and P. Pyle (2016). Age structure of Black-backed Woodpecker populations in burned forests. Auk 133(1):69–78. Close , 14 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ). This has not been confirmed in the Northern Flicker, but retention of 1–2 juvenile primary coverts should be looked for in a small proportion of third basic individuals (see images under Third Basic Plumage).

Definitive Prebasic Molt

Incomplete to complete, primarily July–October (Figure 1), on or near breeding grounds. All tracts are completely replaced, except primary coverts and/or secondaries can be incompletely replaced in some individuals. Sequence of primary covert and secondary replacement appears to continue where previous Prebasic Molt arrested, while a new sequence can commence, resulting in Staffelmauser-like patterns. In these individuals, retained basic primary coverts and secondaries occur throughout these tracts and may or may not occur in consecutive pairs or blocks as are retained juvenile feathers of Second Basic and Third Basic plumages, and retained feathers are less-often located symmetrically between the wings. One to 4 retained basic secondaries can occur among s1–s8 in approximately 18% of individuals, and a variable number of primary coverts can be retained at different positions among the tract (13 Pyle, P., and S. N. G. Howell (1995). Flight-feather molt patterns and age in North American woodpeckers. Journal of Field Ornithology 66(4):564–581. Close , 14 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ). Replacement sequence in other tracts as described above.

Bill and Gape

In hatchlings, the bill is pale pinkish-cream, becoming gray before fledging and the gape is pale pink/orange. The mandibles of nestlings are tipped with white. In adults, the bill is black to brownish black during breeding.

Iris

In juveniles (April–September), the iris is gray-brown, becoming deeper reddish brown to yellowish brown in adults (14 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ).

Tarsi and Toes

In hatchlings, the legs and feet are pale pinkish, becoming gray before fledging, In adults, bluish gray or gray (8 Ridgway, R. (1914). The birds of North and Middle America. Bulletin of the United States National Museum 50, part VI. Close ).

Linear Measurements

Variable among subspecies and geographically within subspecies. Body length 30–35 cm, wingspan 54 cm (35 Palmer, E. L., and H. S. Fowler (1975). Field Book of Natural History. Second edition. McGraw Hill Press, New York, NY, USA. Close ). Short (1 Short, L. L. (1965). Hybridization in the flickers (Colaptes) of North America. Bulletin of the American Museum of Natural History 129:307–428. Close , 2 Short, L. L. (1967). Variation in Central American flickers. Wilson Bulletin 79(1):5–21. Close ) provided useful comparisons among subspecies: Red-shafted Flicker (cafer) is the largest subspecies and Cuban Flicker (chrysocaulosus) averages the smallest; Yellow-shafted Flicker (auratus) and Guatemalan Flicker (mexicanoides) are intermediate, based on measures of bill, tarsus, wing and tail (see Table 2). Care must be taken when comparing measurements from different authors who may differ in technique, but body size seems to increase in northern populations, as shown in a comparison of Red-shafted Flicker in central British Columbia (see Table 3) with Short's population in the central United States (Table 2). Males are significantly larger than females in all measures, but only by about 1–2%, and second-year birds have shorter feather lengths than older individuals (Table 3). See also Geographic Variation.

Mass

Females weigh significantly less than males and, during the breeding season, the body mass of both sexes drops during the transition from incubation to nestling feeding. Mean mass of breeding adults in Riske Creek, British Columbia: female 153.6 g ± 9.14 SD (range 124–182, n = 1,355), male 160.6 g ± 8.99 SD (range 131–188, n = 1,390) (KLW); east-central Nebraska: female 131.8 g ± 7.46 SD (range 117–150, n = 20), male 139.6 g ± 8.08 SD (range 129–154, n = 17); north-central Colorado: female 139.2 g ± 4.63 SD (range 130–145, n = 6), male 156.5 g ± 7.85 SD (range 143–167, n = 9) (1 Short, L. L. (1965). Hybridization in the flickers (Colaptes) of North America. Bulletin of the American Museum of Natural History 129:307–428. Close ); western Pennsylvania: year-round adults: female 129.0 g ± 7.67 SD (range 106–164, n = 65), male 135.0 g ± 6.37 SD (range 114–160, n = 94) (36 Dunning, J. B., Jr. (1993). CRC Handbook of Avian Body Masses. CRC Press, Boca Raton, FL, USA. Close ).