Green-tailed Goldenthroat Polytmus theresiae Scientific name definitions

The Green-tailed Goldenthroat inhabits the edges of sandy forests or sandy savannas with scattered bushes. This species gathers nectar from scattered plants, especially those in the Melostomataceae genus, and forages for insects by hawking or gleaning. Male Green-tailed Goldenthroat are entirely green, and females are mostly green with green speckles on white underparts. Both sexes are smaller than the very similar White-tailed Goldenthroat (Polytmus guainumbi).

8·9–9·9 cm (including bill 2·5 cm); 3·0–3·9 g (1 Grantsau, R. (1988). Os Beija-flores do Brasil. Expressão e Cultura, Rio de Janeiro, Brazil. Close ). Male  has long bill  , slightly decurved, upper mandible black, lower pinkish, tipped black; upperparts  and underparts shining green, small white postocular spot; tail roundish, central rectrices green, others green, basally white. Female similar to male, smaller; throat and breast whitish, thickly spotted with green; outer rectrices with narrow white tips. Juvenile like adult female but with head feathers fringed buff.

Formerly separated in monotypic genus Smaragdites.

Forest edge and sandy savanna with scattered stands of bushes and small trees from 100 to 300 m altitude.

Sedentary, but some wandering is known in Suriname, where species may occur at coastal mangrove areas in January–February.

Nectar  of flowering Melostomataceae. Arthropods are gleaned from leaves or caught in the air by hawking. Male occasionally occupies feeding territories  ; usually both sexes forage by trap-lining.

Vocal Array

Song. A repeated, whinnying series of 20–25 thin nasal notes, typically first rising then slightly falling, and fading at the end. Duration c. 2–3 seconds, fundamental frequency around 2kHz, with 3rd to 5th harmonic also loud. Shorter versions of song phrase, with fewer notes and flat-pitched, are also uttered and may have a different function .

Kek. A short nasal kek or kuk is uttered at intervals when feeding.

Other. Also single high-pitched tsit notes have been reported.

Geographic Variation

Song is structurally similar over its entire range, but pace of notes in song phrase is slightly higher in Colombia and even faster in the isolated population of NW Peru. Whether there is an east-west clinal variation in song pace or rather two distinct vocal groups requires further investigation.

Phenology

Little information. Recordings of song are available from all months of the year, but there are likely regional differences.

Daily Pattern of Vocalizing

Mainly sings in early morning and from late afternoon till dusk. Lek gathering, in which several birds continuously sing from a perch only separated some 20-50m from each other , apparently mainly occurs during the evening till dusk.

Places of Vocalizing

Birds sing from a perch in open habitat, either some tall grass stem or a twig in a small shrub at a height of ⁓1.0‒2.0m.

Sex Differences

Little information. Song is uttered by males, possibly also by females (only short song phrases?).

Social Context and Presumed Functions of Vocalizations

Little information. Lekking behavior suggests several males sing to compete and attract a female.

None documented.

March–April and August–October (the Guianas), October–November (Venezuela), November–March (Brazil). Small cup-shaped nest of fine, buff-colored plant fiber and cobweb is built, rather visibly, in fork of low shrub, often Melostomataceae such as Rhynchanthera or Tibouchina. Nest height 42 mm, external diameter 37 mm, internal diameter 33 mm (1 Grantsau, R. (1988). Os Beija-flores do Brasil. Expressão e Cultura, Rio de Janeiro, Brazil. Close ). Clutch size two eggs, size 15 mm × 9·1 mm, mass 0·54–0·58 g (1 Grantsau, R. (1988). Os Beija-flores do Brasil. Expressão e Cultura, Rio de Janeiro, Brazil. Close ); incubation 14 days, by female; chick  black with two rows of buff dorsal down; fledging period 20 days, sometimes up to 28 days.

Not globally threatened (Least Concern). CITES II. A common and locally very abundant savanna bird at table mountain borders in La Gran Sabana, southern Venezuela, and similar habitats in Suriname and French Guiana.