Plumages, Molts, and Structure

The Canyon Wren has 10 primaries (numbered distally, p1 to p10, with p10 reduced in length), 9 secondaries (numbered proximally, s1 to s9, and including 3 tertials, s7 to s9 in passerines), and 12 rectrices (numbered bilaterally, r1 to r6, on each side of the tail). See Molts for molt and plumage terminology. The following is based primarily on detailed plumage descriptions of Ridgway (7 Ridgway, R. (1904). The Birds of North and Middle America Part III. Bulletin of the United States National Museum 50. Close ), Oberholser (8 Oberholser, H. C. (1974). The Bird Life of Texas. University of Texas Press, Austin, TX, USA. Close ), and Howell and Webb (9 Howell, S. N. G., and S. Webb (1995). A Guide to the Birds of Mexico and Northern Central America. Oxford University Press, New York, NY, USA. Close ); see Pyle (10 Pyle, P. (1997). Identification Guide to North American Birds Part I. Slate Creek Press, Bolinas, CA, USA. Close ) for criteria used for age and sex determinations. Geographic variation in appearance is slight; the following pertains to the northern subspecies (C. m. conspersus and C. m. albifrons); see Systematics: Subspecies for differences in the nominate subspecies of central Mexico. Sexes are similar in all plumages; definitive appearance is assumed at the Second Basic Plumage.

Natal Down

Present primarily May–July, in the nest. Hatchlings are born largely naked. Natal down described as "dull tilleul buff, pale vinaceous buff, or drab" (8 Oberholser, H. C. (1974). The Bird Life of Texas. University of Texas Press, Austin, TX, USA. Close ), or gray and in sparse tufts on crown (3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ).

Juvenile (First Basic) Plumage

Present primarily April–August. Similar to Definitive Basic plumage but overall duller, otne grayer, sometimes darker chestnut brown; crown throat and breast variable pale gray to dull whitish; upperparts more coarsely vermiculated dusky and fewer or no white specks or dots; upperwing coverts with heavier black bars and cinnamon tips (see Figure 220 in 10 Pyle, P. (1997). Identification Guide to North American Birds Part I. Slate Creek Press, Bolinas, CA, USA. Close ); bars of juvenile primaries and secondaries tend to line up as in other wrens (cf. 11 Taylor, R. C. (2012). Ageing Wrens Troglodytes troglodytes using the barring pattern across remiges. Ringing & Migration 27:106–108. Close ); white throat and breast sometimes speckled with black; chestnut of abdomen duller, often grayer, with no or less distinct narrow dusky bars; juvenile body feathering (especially undertail coverts) filamentous due to lower barb densities.

Formative Plumage

"First Basic" or "Basic I" plumage of Humphrey and Parkes (12 Humphrey, P. S., and K. C. Parkes (1959). An approach to the study of molts and plumages. Auk 76(1):1–31. Close ) and some later authors; see revision by Howell et al. (13 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 Definitive Basic plumage but can be identified by molt limits (contrasts) between replaced formative and retained juvenile upperwing feathers; one or more juvenile outer greater coverts and all primary coverts retained, relatively worn and faded, with more distinct and bar-like dark markings (see Figure 220 in 10 Pyle, P. (1997). Identification Guide to North American Birds Part I. Slate Creek Press, Bolinas, CA, USA. Close ), the greater coverts with rufous tips, contrasting with replaced inner greater coverts or median coverts with whiter tips; 1–3 tertials usually replaced (s8, s8–9, or s7–s9), contrasting with retained tertials or outer secondaries; juvenile primaries and rectrices retained, the remiges showing more-even bars as in Juvenile but not showing molt clines, the outer primaries relatively narrow, brownish, and worn, and the rectrices relatively narrow and abraded.

Definitive Basic Plumage

Present primarily September–August.

Crown and nape are variably dark to pale gray or brownish gray, the feather tips with sparse to extensive black subterminal bands and white tips forming speckled appearance, the grayish coloration extending variably into the upper back; remainder of upperparts brown to rufous-brown, often more rufous on the rump and uppertail coverts, with speckled black-and-white pattern present variably through back, but less so on rump or uppertail coverts; rectrices cinnamon-rufous with 5–6 narrow and distinct dark bands. Upper sides of head and auriculars same color as crown, usually with very indistinct darker eyeline (variably broadening to include auriculars) and paler supercilium. Upperwing coverts brown to rufous brown, the lesser and median coverts with speckled pattern of back, the greater coverts with whitish to pale cinnamon tips, and the greater and primary coverts with indistinct bar-like markings (see Figure 220 in 10 Pyle, P. (1997). Identification Guide to North American Birds Part I. Slate Creek Press, Bolinas, CA, USA. Close ); tertials rufous with distinct dark bars; primaries and remainder of secondaries dusky brown, the outer webs rufous with uneven dark bars; upperwing can look entirely rufous with variably distinct barring when wing closed. Malar region below eye, chin, throat, sides of neck, and breast immaculate white, forming prominent white bib; belly through undertail coverts dark rufous to cinnamon-rufous (sometimes pinkish cinnamon in transition area), the feathers usually with indistinct dark spotting or barring and pale tips when fresh; underwing coverts dull cinnamon and grayish, some feathers with white tips.

Definitive Basic Plumage distinguished from Formative Plumage by upperwing coverts and tertials uniform in wear, without molt limits, the primary coverts with weaker and less bar-like dark markings; primaries and secondaries duskier and glossier with broader tips, less-even barring as in other wrens (cf. 11 Taylor, R. C. (2012). Ageing Wrens Troglodytes troglodytes using the barring pattern across remiges. Ringing & Migration 27:106–108. Close ), and showing molt clines from more-worn p1 to fresher p10 and more worn s1 to fresher s6; rectrices broader and relatively fresher.

Molt and plumage terminology follows Humphrey and Parkes (12 Humphrey, P. S., and K. C. Parkes (1959). An approach to the study of molts and plumages. Auk 76(1):1–31. Close ), as modified by Howell et al. (13 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 Canyon Wren exhibits a Complex Basic Strategy (cf. 13 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 , 14 Howell, S. N. G. (2010). Peterson Reference Guide to Molt in North American Birds. Houghton Mifflin Harcourt, Boston, Massachusetts, USA. Close ), including complete prebasic molts and a partial preformative molt but no prealternate molts (8 Oberholser, H. C. (1974). The Bird Life of Texas. University of Texas Press, Austin, TX, USA. Close , 10 Pyle, P. (1997). Identification Guide to North American Birds Part I. Slate Creek Press, Bolinas, CA, USA. Close , Figure 1).

Prejuvenile (First Prebasic) Molt

Complete, primarily April–July, in the nest. Little information on sequence of juvenile plumage development. Feathers emerge from pins around day 8. Molt of body feathers close to complete by fledging at 13–16 d but outer primaries and (especially) rectrices may take up to a week post-fledging to complete growth.

Preformative Molt

"First Prebasic" or "Prebasic I" molt of Humphrey and Parkes (12 Humphrey, P. S., and K. C. Parkes (1959). An approach to the study of molts and plumages. Auk 76(1):1–31. Close ) and later authors; see revision by Howell et al. (13 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 ). Partial, primarily August–October (Figure 1). Includes all body feathers and lesser upperwing coverts, most to all median coverts, 2 to all 10 (in ca. 8% of birds) greater coverts, and usually (in ca. 92% of birds) 1–3 tertials but no primaries, rectrices, or other secondaries (15 Pyle, P. (1997). Molt limits in North American passerines. North American Bird Bander 22:49–89. Close , 10 Pyle, P. (1997). Identification Guide to North American Birds Part I. Slate Creek Press, Bolinas, CA, USA. Close ).

Definitive Prebasic Molt

Complete, primarily July–October Figure 1. Primaries are replaced distally (p1 to p10), secondaries are replaced bilaterally from the second tertial (s8) and proximally from s1, and rectrices are generally replaced proximally on each side of the tail (r6 to r1), with some variation probable. Barring across remiges may reflect growth bars, each bar representing a day of growth (11 Taylor, R. C. (2012). Ageing Wrens Troglodytes troglodytes using the barring pattern across remiges. Ringing & Migration 27:106–108. Close ). Sequential molt of primaries results in bars not lining up as well and in juvenile primaries that are grown synchronously, as in other wrens (11 Taylor, R. C. (2012). Ageing Wrens Troglodytes troglodytes using the barring pattern across remiges. Ringing & Migration 27:106–108. Close ).

Bill and Gape

Mandible dull whitish or yellowish, becoming grayish or dusky terminally; maxilla dusky horn, with paler tomia (7 Ridgway, R. (1904). The Birds of North and Middle America Part III. Bulletin of the United States National Museum 50. Close ). Gape yellow, swollen and more prominent in nestlings and juveniles (SLJ).

Iris

Brown (7 Ridgway, R. (1904). The Birds of North and Middle America Part III. Bulletin of the United States National Museum 50. Close ).

Tarsi and Toes

Black to dark brown (7 Ridgway, R. (1904). The Birds of North and Middle America Part III. Bulletin of the United States National Museum 50. Close ).

Linear Measurements

Mean total length 13.0 cm (range 11.4–15.4, n = 286). On average, males are larger than females, particularly in exposed culmen, wing chord, and tail length, but all morphometric measurement ranges overlap between the sexes (Table 1). One study found that mean culmen length is longer in males than in females, but bill depth did not differ between sexes (2 Mirsky, E. N. (1976). Ecology of coexistence in a wren-wrentit-warbler guild. Ph.D. dissertation, University of California, Los Angeles, CA, USA. Close ). From museum species (subspecies conspersus) measured by SLJ and JSD, mean wing chord of females 58.06 mm (range 50.0–65.0, n = 36) and males 59.59 mm (range 52.0–69.0, n = 74); mean tail length of females 51.52 mm (range 43.0–59.0, n = 33) and males 53.27 mm (range 44.0–65.0, n = 75); mean culmen length of females 18.73 mm (range 15.1–22.1, n = 34) and males 20.01 mm (range 12.4–23.9, n = 76) (Table 1).

Mass

Mean adult mass (C. m. conspersus): female 11.1 g (range 9.9–12.2, n = 13); male 11.4 g (range 9.9–14.8, n = 42) (16 Jones, S. L., and J. Scott Dieni (1995). Canyon Wren (Catherpes mexicanus). In The Birds of North America, No. 197 (A. Poole and F. Gill, Editors). Academy of Natural Sciences, Philadelphia, PA and American Ornithologists' Union, Washington DC, USA. Close ). See Table 1.