Plumages, Molts, and Structure

Chihuahuan Meadowlark has 9 functional primaries (numbered distally from innermost p1 to outermost p10), 9 secondaries (numbered proximally from outermost s1 to innermost s9 and including 3 tertials, s7-s9 in passerines), and 12 rectrices (numbered distally, r1 to r6 on each side of the tail). Wings are moderately rounded and rectrices are attenuated. Geographic variation is slight (see Systematics for subspecies descriptions). The following plumage descriptions pertain to all populations and are based on those of Ridgway (1 Ridgway, R. (1902). The birds of North and Middle America. Part II. United States National Museum Bulletin 50, part 2. Close ), Oberholser (2 Oberholser, H. C. (1974). The Bird Life of Texas. University of Texas Press, Austin, TX, USA. Close ), and Jaramillo and Burke (3 Jaramillo, A., and P. Burke (1999). New World Blackbirds: the Icterids. Princeton University Press, Princeton, NJ, USA. Close ); see Pyle (4 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ) for criteria to determine age and sex. See Molts for molt and plumage terminology. Plumage appearance becomes brighter for breeding in spring-summer due to wearing off of feather veiling in early spring (and not due to molt). Definitive-like appearance is assumed following the complete Preformative Molt. Sexes show broadly similar appearance in all plumages, although males are larger and average brighter and more extensively yellow than females, especially after feather veiling wears off (see below).

Natal Down

Present primarily April–July, in the nest. Not described for Chihuahuan Meadowlark but for Eastern Meadowlark (Sturnella magna) natal down described as "light drab to drab-gray" (2 Oberholser, H. C. (1974). The Bird Life of Texas. University of Texas Press, Austin, TX, USA. Close ), and for Western Meadowlark (Sturnella neglecta) natal down described as "pale cartridge buff" (2 Oberholser, H. C. (1974). The Bird Life of Texas. University of Texas Press, Austin, TX, USA. Close ), “pale” (5 Grinnell, J., and J. Linsdale (1936). Vertebrate animals of Point Lobos Reserve, 1934–1935. Carnegie Institute Publication, Washington, DC, USA. Close ), “pearl gray” (6 Bent, A. C. (1958). Life histories of North American blackbirds, orioles, tanagers, and their allies. United States National Museum Bulletin 211. Close ), and “conspicuously whitish” (7 Linsdale, J. M. (1936). Coloration of downy young birds and of nest linings. Condor 38:111-117. Close ). Down also described as longest and most abundant on capital and spinal tracts, shorter on humeral and femoral tracts, and down on head localized chiefly above eyes and on occiput (6 Bent, A. C. (1958). Life histories of North American blackbirds, orioles, tanagers, and their allies. United States National Museum Bulletin 211. Close ).

Juvenile Plumage

Present primarily June–September. Similar to that of Definitive Basic Plumage (below), but plumage often washed buff when fresh; upperparts often paler, the feathers including scapulars, upperwing coverts, and tertials with less-distinct dark barring and margined and tipped more distinctly and broadly with whitish or buff; head stripes less sharply defined, the superciliary stripe dull buff throughout; yellow of underparts paler and/or more restricted; sides and flanks much less distinctly streaked; black crescent of breast lacking, replaced by brownish mottling or flecking. Sexes may be indistinguishable, although juveniles with more extensive yellow to the breast and the sides of the head are likely males.

Formative Plumage

Present primarily September–August. Following the complete Preformative Molt, this plumage is indistinguishable from Definitive Basic Plumage (below).

Definitive Basic Plumage

Present primarily September–August. Center of crown brown to blackish-brown with pale flecking when fresh; nape pale with dark flecking; remainder of upperparts including two pairs of central rectrices brown with barred blackish patterning, feathers of the back and scapulars margined laterally (but not tipped) with white when fresh. Outer four rectrices primarily white, the fourth pair (r2) with variable dark edging to the inner and outer webs and the outer three pairs (r4-r6) usually with thin dark subterminal shaft streaks, often barely noticable (see Figure 326 in 8 Pyle, P. (1997). Identification Guide to North American Birds. Part I. Slate Creek Press, Bolinas, CA, USA. Close , or Figure 284 in 4 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ). Sides of head with distinct whitish supercilium, the anterior portion (lores) deep yellow; broad dark brown to blackish-brown eyeline indistinct or absent in front of eye and extends prominently behind eye to sides of neck; remainder of face whitish, the auriculars pale and unstreaked. Upperwing lesser coverts brown with dark barring; median coverts with dusky blackish centers and pale fringing; alula starkly blackish with pale edging when fresh; primary coverts brownish to cinnamon-brown with indistinct barring and darker terminal regions; greater coverts, tertials, secondaries, and primaries brown with dark barring, the barring more prominent on the tertials and less prominent on the primaries. Malar region whitish; chin throat, and center of underparts rich yellow to saffron with a distinct black V-shaped patch extending from sides of the throat to center of the breast; sides of underparts and flanks broadly whitish with thin short dark brown streaking that rarely touches the yellow of the breast; undertail coverts whitish with thin dark streaks.

Feathers of the face and underparts are extensively veiled with buff when fresh, creating a subdued appearance; buff wears off to reveal brighter underlying colors in March-August. Wear by end of breeding season can create paler and abraded upperparts with less-distinct patterning. Sexes are similar but females average duller than males, with paler and less-extensive yellow, especially in the lores (see Figure 325 in 8 Pyle, P. (1997). Identification Guide to North American Birds. Part I. Slate Creek Press, Bolinas, CA, USA. Close , or Figure 283 in 4 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ), and with the black V-shaped patch to the underparts somewhat more restricted. Along with the males being significantly larger than females (see Measurements), birds showing extremes in these plumage differences can be reliably sexed (4 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ).

General

Molt and plumage terminology follows Humphrey and Parkes (9 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. (10 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 ). Chihuahuan Meadowlark exhibits a Complex Basic Strategy (cf. 10 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 ), including complete preformative and prebasic molts but no prealternate molts (6 Bent, A. C. (1958). Life histories of North American blackbirds, orioles, tanagers, and their allies. United States National Museum Bulletin 211. Close , 2 Oberholser, H. C. (1974). The Bird Life of Texas. University of Texas Press, Austin, TX, USA. Close , 4 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ).

Prejuvenile (First Prebasic) Molt

Complete, primarily May–July, in the nest. No specific information known for Chihuahuan Meadowlark. For Eastern Meadowlark, feather tracts show developing contour feathers by day 3; feathers emerge from sheaths by day 6; by day 10–12 (when typically fledging), body fully covered by feathers but flight feathers still partly sheathed; incapable of sustained flight but strong, nearly full-sized legs enable bird to run quickly. At day 15–16, flight feathers still ensheathed basally, but bird capable of short flights; sustained flight by day 21.

Preformative Molt

"First Prebasic" or "Prebasic I" Molt according to Humphrey and Parkes (9 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. (10 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 ). Complete, primarily June–November, on or near breeding grounds. Other blackbirds can retain underwing greater and/or primary coverts during the preformative molt (4 Pyle, P. (2022). Identification Guide to North American Birds. Part I, Second Edition. Slate Creek Press, Forest Knolls, CA, USA. Close ) and this could occur in meadowlarks; study needed. Replacement sequence of flight feathers the same as in Definitive Prebasic Molt.

Definitive Prebasic Molt

Complete, primarily June–November, on or near breeding grounds, although study is needed on molting locations relative to breeding territories (cf. 11 Pyle, P., J. F. Saracco, and D. F. DeSante (2018). Evidence of widespread movements from breeding to molting grounds by North American landbirds. Auk: Ornithological Advances 135:506–520. Close ). Primaries replaced distally (p1 to p9), secondaries replaced proximally from s1 and bilaterally from the middle tertial (s8; s6 can drop after or before s5), and rectrices probably replaced more-or-less distally (r1 to r6) on each side of tail (as indicated in Macaulay Library images), although look for synchronous or proximal replacement of rectrices as reported for other blackbirds (12 Parkes, K. C. (1972). Tail molt in the family Icteridae. Paper read at Proceedings of the XVth International Ornithological Congress. The Hague, the Netherlands, Leiden, the Netherlands. Close ).

Bill And Gape

Bill pinkish buff in juveniles. In adults slaty or dull clay color. Upper mandible black or dusky, edged with paler tones; lower mandible grayish blue with dusky tip in life . In nestlings edges of mouth bright yellow; mouth lining pinkish.

Iris

Brown.

Tarsi and Toes

Pinkish buff in juveniles. In adults dusky pinkish.

See Appendix 1. Males larger than females.