Plumages, Molts, and Structure

Mrs. Moreau's Warbler has 10 primaries (numbered distally, from innermost p1 to outermost p10, the p10 reduced in length), 9 secondaries (numbered proximally, from outermost s1 to innermost s9 and including 3 tertials, s7‒s9 in passerines), and 12 rectrices (numbered distally, from innermost r1 to to outermost r6 on each side of the tail). The following plumage descriptions are based on those of Moreau (1 Moreau, R. E. (1938). A new Artisornis. Bulletin of the British Ornithologists' Club 58:139. Close , 2 Moreau, R. E. (1946). The adult of Mrs Moreau’s Warbler. Bulletin of the British Ornithologists' Club 66:44. Close ), Williams (3 Williams, J. G. (1951). Notes on Scepomycter winifredae and Cinnyris loveridgei. Ibis 93:469–470. Close ), Ryan (4 Ryan, P. G. (2006) Family Cisticolidae (cisticolas and allies). In Handbook of the Birds of the World, Volume 11 (J. del Hoyo, A. Elliott, and D. Christie, Editors). Lynx Edicions, Barcelona, Spain, pp. 378–491. Close ), and Bowie et al. (5 Bowie, R. C. K., J. Fjeldså, and J. Kiure (2009). Multilocus molecular DNA variation in Winifred’s Warbler Scepomycter winifredae suggests cryptic speciation and the existence of a threatened species in the Rubeho–Ukaguru Mountains of Tanzania. Ibis 151:709–719. Close ), along with examination of Macaulay Library images. See Systematics for slight geographic variation in plumage and see Molts for molt and plumage terminology. Definitive appearance may be attained following the preformative molt (if complete) or following the second prebasic molt; study is needed. Sexes are likely similar in plumage, as in other species of Cisticolidae.

Natal Down

Information needed.

Juvenile (First Basic) Plumage

Birds collected in January and February (probably shortly after fledging; see Phenology) were dark olive-brown above, and olive-buff below with dense grayish mottling (5 Bowie, R. C. K., J. Fjeldså, and J. Kiure (2009). Multilocus molecular DNA variation in Winifred’s Warbler Scepomycter winifredae suggests cryptic speciation and the existence of a threatened species in the Rubeho–Ukaguru Mountains of Tanzania. Ibis 151:709–719. Close ).

Formative Plumage

Individuals collected in June and July, described as older juveniles, had the forehead and crown olive green intermixed with rufous brown (1 Moreau, R. E. (1938). A new Artisornis. Bulletin of the British Ornithologists' Club 58:139. Close ), with the chin dusky white, merging to pale rufous gray on the throat and upper breast, and the remainder of the underparts pale yellowish gray with indistinct barring in the center of the belly (1 Moreau, R. E. (1938). A new Artisornis. Bulletin of the British Ornithologists' Club 58:139. Close , 3 Williams, J. G. (1951). Notes on Scepomycter winifredae and Cinnyris loveridgei. Ibis 93:469–470. Close ). These birds may have been undergoing the Preformative Molt, following which Formative plumage may essentially be indistinguishable from Definitive Basic plumage. Study is needed on whether or not some juvenile flight feathers can be retained following the Preformative Molt, allowing separation of birds in formative plumage.

Definitive Basic Plumage

The entire head, throat, and upper-central breast are rufous. The upperparts are dark gray with an olivaceous tinge. The wings and tail are dusky black with an olivaceous wash on the outer edges of the primaries and outer tail feathers. The sides of the breast are buffy-gray brown with the center of the upper belly buff. The rest of the belly, flanks, thighs, vent, and undertail coverts are buffy grayish brown with an olive tinge.

The upperwing coverts and wing feathers are uniformly basic following complete molt. Basic primaries, secondaries, and rectrices are likely broader and more squared than juvenile feathers, as in other species of Cisticolidae. The lack of molt limits may allow the separation of Definitive Basic from Formative plumage, but study is needed.

Molt and plumage terminology follows Humphrey and Parkes (6 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. (7 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 ). Under this nomenclature, terminology is based on evolution of molts along ancestral lineages of birds from ecdysis (molts) of reptiles, rather than on molts relative to breeding season, location, or time of the year, the latter generally referred to as “life-cycle” molt terminology (8 Jenni, L., and R. Winkler (2020). Moult and Ageing of European Passerines. Second edition. Bloomsbury, London, United Kingdom. Close ; see also 9 Pyle, P. (2022). Defining moults in migratory birds: A sequence-based approach. Journal of Avian Biology e02958. Close , 10 Kiat, Y. 2022. Moult terminology: Let’s make it simpler! Ibis. Close ). In north-temperate latitudes and among resident passerines, the Humphrey-Parkes and life-cycle nomenclatures correspond to some extent, but terms are not synonyms due to the differing bases of definition. Prebasic molts often correspond to “post-breeding“ or “post-nuptial“ molts, and preformative molts often correspond to “post-juvenile“ molts. The terms prejuvenile molt and juvenile plumage are preserved under Humphrey-Parkes terminology (considered synonyms of first prebasic molt and first basic plumage, respectively) and the former terms do correspond with those in life-cycle terminology.

There is very little information on molt strategies of Mrs. Moreau's Warbler. It likely shows a Complex Basic Molt Strategy (see 7 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 ), with preformative and prebasic molts but no prealternate molts, as in other species of Cisticolidae. Study is needed on the extent of the preformative molt, reported as usually complete but sometimes of variable extent in Cisticola (11 Gauci, C., and J. Sultana (1981). The moult of the Fan-tailed Warbler. Bird Study 28(2):77‒86. Close , 12 Higgins, P. J., J. M. Peter, and S. J. Cowling, Editors (2006). Handbook of Australian, New Zealand and Antarctic Birds. Volume 7, Part B: Dunnock to Starlings. Oxford University Press, Melbourne, Australia. Close , 13 Blasco-Zumeta, J., and G.-M. Heinze (2022). Zitting Cisticola. Identification Guide of Birds of Aragón and Continental Spain. Aranzadi Sciences Society, Donostia-San Sebastián, Spain. Close ). As in other species of Cisticolidae, primaries are likely replaced distally (from p1 to p10), secondaries are replaced bidirectionally from the middle tertial (s8) and proximally from s1 such that the last feather replaced is s5 or s6, and rectrices are generally replaced distally from the central r1 to the outer r6 on each side of the tail, with some variation occurring.

From Ripley and Heinrich (14 Ripley, S. D., and G. Heinrich (1966). Comments on the avifauna of Tanzania I. Postilla 96:1–45. Close ).

Bill and Gape

Bill black.

Iris and Facial Skin

Eyes dark brown.

Tarsi and Toes

Legs and feet dark gray.

Linear Measurements

Uluguru Mountains, Tanzania

• Mean wing length, adult male 55.5 mm (56, 56, n = 2) (14 Ripley, S. D., and G. Heinrich (1966). Comments on the avifauna of Tanzania I. Postilla 96:1–45. Close ).
• Mean wing length, unsexed 57.5 mm (range 52.2‒60.7, n = 13) (5 Bowie, R. C. K., J. Fjeldså, and J. Kiure (2009). Multilocus molecular DNA variation in Winifred’s Warbler Scepomycter winifredae suggests cryptic speciation and the existence of a threatened species in the Rubeho–Ukaguru Mountains of Tanzania. Ibis 151:709–719. Close ).

Ukaguru and Rubeho Mountains, Tanzania

• Mean wing length, unsexed 58.1 mm (range 55.1‒60.8, n = 7) (5 Bowie, R. C. K., J. Fjeldså, and J. Kiure (2009). Multilocus molecular DNA variation in Winifred’s Warbler Scepomycter winifredae suggests cryptic speciation and the existence of a threatened species in the Rubeho–Ukaguru Mountains of Tanzania. Ibis 151:709–719. Close ).
• Mean bill length (exposed culmen), unsexed 14.4 mm (range 13.6‒15.7, n = 7) (5 Bowie, R. C. K., J. Fjeldså, and J. Kiure (2009). Multilocus molecular DNA variation in Winifred’s Warbler Scepomycter winifredae suggests cryptic speciation and the existence of a threatened species in the Rubeho–Ukaguru Mountains of Tanzania. Ibis 151:709–719. Close ).
• Mean tarsus length, unsexed 23.5 mm (range 22.8‒25.6, n = 7) (5 Bowie, R. C. K., J. Fjeldså, and J. Kiure (2009). Multilocus molecular DNA variation in Winifred’s Warbler Scepomycter winifredae suggests cryptic speciation and the existence of a threatened species in the Rubeho–Ukaguru Mountains of Tanzania. Ibis 151:709–719. Close ).

Mass

Uluguru Mountains, Tanzania

• Mass, female 16.5 g (n = 1) (L. Hansen, unpublished data).
• Mean mass, unsexed 16.6 g (range 15.5‒18.0, n = 4) (L. Hansen, unpublished data).