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Microcerculus philomela

Nightingale Wren

  • Order: Passeriformes
  • Family: Troglodytidae
  • Monotypic

Authors: Rentschlar, Kate, C. Soberanes-González, C. Rodríguez-Flores, and M. C. Arizmendi

Identification

Summary

Overall, Nightingale Wren is a dark bird; from a distance it appears to be entirely dark brown or black. Males and females are similar in size. It has a long, slender bill and a very short tail. The body is dark brown, with a pale gray throat and breast. Feathers on both the upperparts and underparts are tipped black, producing a scalloped pattern. There also are white to pale buff tips to the upperwing coverts. Juveniles are similar to adults, but the crown and upperparts have pale gray scaling and the underparts are sparsely flecked whitish.

Similar Species

At the very southern edge of its range, Nightingale Wren may be confused with Scaly-breasted Wren (Microcerculus marginatus), but Scaly-breasted is much paler below, with less scaling, than Nightingale Wren. Juveniles of the two species look very similar; because they cannot be confidently distinguished visually, location is the best means of identification. Nightingale Wren also is similar to the other wrens in the genus Microcerculus, which occur allopatrically in South America.

Vocalizations

Song

One can assume with a name like Nightingale Wren, recalling the Common Nightingale (Luscinia megarhynchos) which is famous throughout European literature for its melodic song (Chandler 1934), that this species would have an equally impressive song. Nightingale Wren’s song has been described as "haunting"; listeners are unable to discern a definite reoccurring pattern in their song and because of this, the pattern of the song has been labeled as "random" (Howell and Webb 1995). Howell and Webb (1995) describe the song of Nightingale Wren as "confident to hesitant, rising and falling series of whistles… hee hoo, hee hoo, hoo hoo hee hoo, ss hoo hee…or tee tee-tee-tee ssi tee tee-tee-tee-tee-tee tee tee-tee ssi". Although hard to describe the song, after hearing it once it is unmistakable. Leger et al. (2000) showed that, in fact, there is a pattern to the song. They found that the wren has only one song with about 32 notes in it. The variation and seeming randomness of their song is due to stoppages of singing at almost any point in the song and then starting their song over from the beginning after a brief pause. Stiles (1983) notes that there is some local variation within the population, "in other dialects the rhythm may be slightly more choppy, the song itself less strikingly melodious". He also points out that the "pure-tone" of their whistles helps transmit the song in an "obstruction filled habitat" (Stiles 1984). Slud (1958) hypothesized that Nightingale Wren’s song allows males and females to find one another for mating purposes. His other hypothesis is that it deters birds from intruding on occupied territories. Stiles (1984) collected data to support the latter hypothesis; he found that males respond strongly by answering and approaching a played recording of another Nightingale Wren singing, even a different dialect. The song is sung almost all year round, not just specifically in the breeding season.

Other vocalizations

Other vocalizations include a sharp "stchep" or "stchip" or "tseck", a light chatter, and a single long note that resembles the whistle of Broad-winged Hawk (Buteo platypterus) (Slud 1958).

Nonvocal Sounds

None reported.

Detailed Description (appearance)

Nightingale Wren is considered to have the "most complex and variable plumage" in the family Troglodytidae (Stiles 1983). The following description is based on Stiles (1983).

Adult: Sexes are similar; males are slightly larger (see Measurements). Upperparts rich dark brown, scalloped with black. Remiges fuscous, broadly edged with rich brown. Wing coverts fuscous brown. The greater coverts have a bright brown subterminal bar, bordered with dusky; this bar is paler towards the feather shaft, where a small buffy or whitish spot is present, forming an indistinct wing bar of pale dots. Rectrices blackish brown. Underparts dull dark gray, heavily scaled with dusky to brownish black; the scaling is more distinct on the throat, and also is, on average, heavier in males. Flanks and belly dark brown, more or less scalloped fuscous black.

Immature (First Basic?): Resembles the adult. The scaling on the underparts is more distinct, especially on the lower breast and the belly. The gray of the underparts also is paler, contrasting more with the blackish scales. The dark scaling on the breast is less heavy. Males may breed and sing in this plumage.

Juvenile: In juveniles, the under- and upperparts are more contrasting, with the upperparts having heavier and less distinct scaling and the underparts heavily scaled with whitish to pale gray. The wing pattern is similar to that of adults but the pale spots are whiter and more distinct. The scaling of the underparts may be broken up, especially in females, giving the bird a mottled effect of whitish, gray and dusky.

Bare Parts

Iris: dark brown

Bill: black, shading to dark horn on the gonys

Tarsi and toes: blackish

Bare parts color data from Stiles (1983).

Measurements

Total length: 10 cm (Stiles and Skutch 1989), 10-11.5 cm (Howell and Webb 1995).

Linear measurements: Males average slightly larger in all measurements.

Bill length (exposed culmen): male, mean 16.93 ± SD 0.54 mm (range 15.9-18.2 mm, n = 31; Stiles 1983); female, mean 16.86 ± SD 0.56 mm (range 16.0-18.1 mm, n = 21; Stiles 1983)

Wing length (chord): male, mean 55.25 ± SD 1.24 mm (range 52.4-58.6 mm, n = 31; Stiles 1983); female, mean 54.41 ± SD 1.80 mm (range 51.7-58.3 mm, n = 19; Stiles 1983)

Tarsus length: male, mean 20.76 ± SD 0.41 mm (range 19.9-21.5 mm, n = 31; Stiles 1983); female, mean 20.63 ± SD 0.52 mm (range 19.8-21.6 mm, n = 19; Stiles 1983)

Mass: male, mean 18.64 ± SD 1.58 g (range 17.4-21.5 g, n = 7; Stiles 1983); female, mean 17.02 ± SD 0.47 g (range 16.4-17.4 g, n = 4; Stiles 1983)

Molts

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Geographic Variation

Monotypic. Stiles (1983) searched for geographic variation in morphometrics across the range of Nightingale Wren, but concluded that "significant geographical variation … is lacking".

Systematics

Described as Cyphorhinus philomela by Salvin in 1861, with a type locality of Alta Vera Paz, Guatemala.

The nomenclatural history of philomela is complicated; see Stiles (1983) for a complete review. Philomela long was recognized as a distinct monotypic species (Ridgway 1904), confined to Guatemala, or as a polytypic species including populations (squammulatus, corrasus, and taeniatus) from Mexico south to northern South America (Hellmayr 1934). Griscom (1932) further merged all populations from Middle America and northern South America with the marginatus group (occidentalis, marginatus) of Amazonia and of western Colombia and western Ecuador. Note that in the classifications of Griscom (1932) and Hellmayr (1934), philomela includes the taxon luscinia Salvin 1866, of Costa Rica, Panama, and northwestern Colombia.

Slud (1958, 1964) observed that there were two distinct song types present in Costa Rica, although he was unable to match song types with described taxa. Stiles (1983) investigated in more detail the geographic variation of Microcerculus in Costa Rica, with reference to vocalizations, plumage and morphometrics. Stiles concluded that two populations readily could be distinguished, based on concordance of variation in voice, plumage, and measurements; the northern population (Mexico to northern Costa Rica) corresponds to philomela, and he resurrected the name luscinia for the southern population

Currently most authorities recognize Nightingale Wren as a monotypic species, M. philomela, while luscinia is classified as a subspecies of Microcerculus marginatus (Scaly-breasted Wren) (AOU 1998, Dickinson 2003).

Recommended Citation

Rentschlar, Kate, C. Soberanes-González, C. Rodríguez-Flores, and M. C. Arizmendi. 2012. Nightingale Wren (Microcerculus philomela), Neotropical Birds Online (T. S. Schulenberg, Editor). Ithaca: Cornell Lab of Ornithology; retrieved from Neotropical Birds Online: http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=539756