Green Warbler vs Greenish Warbler – differences and similarities in vocalization
Green Warbler (Phylloscopus nitidus) is a regular and locally fairly common winter migrant in Sri Lanka, whereas Greenish Warbler (P. trochiloides) is a rare winter migrant to the country. Both these closely related leaf-warblers are similar in their plumage and the similarity is even very close when at their certain plumage stages. Recognizing them apart can be tricky by their appearance but their vocalization often helps in this to some extent. The Green Warbler’s typical call is trisyllabic and it is in the Greenish Warbler disyllabic, and higher in pitch and delivered in shorter duration (faster in utterance of notes in the syllables).
The Green Warbler also utters the trisyllabic call in higher pitch than the usual typical pitch, which is then similar to the pitch of Greenish Warbler’s call. The Green Warbler also has a few high-pitched, more or less drawn out monosyllabic calls (see below). Further it occasionally utters a disyllabic call too which reminiscent of that of the Greenish Warbler and especially when is uttered in higher pitch it is then very similar in sound to the call of Greenish. (However, analysis of notes in these calls reveals the difference between the two.)
Besides the typical trisyllabic call and the other calls, the Green Warbler utters a few warbling songs (see below), and these are in high pitch as its own high-pitched calls (and those of the Greenish Warbler too.)
The Greenish Warbler has a similar variations in diversity of the vocalization as in the Green, and its songs are very similar to of those of the Green too (see below). Further, it sometimes utters trisyllabic-like call that rather reminiscent of the Green Warbler’s higher-pitched call. However, all vocalizations of the Greenish are higher in pitch than the typical trisyllabic call of the Green Warbler and also structure of notes between the similar-sounding calls of the two warblers is different.
Utterance of songs in between the calls by both these warblers in their wintering grounds is obviously for maintaining and defending individual feeding territory for each bird from others of their own kind during their stay in the tropics away from winter.
Green Warbler’s vocalizations
Typical trisyllabic call of the Green Warbler, recorded at Tanamalwila, Sri Lanka, in Jan. 2016.
Typical trisyllabic call of the Green Warbler in higher pitch than the usual, recorded at Horton Plains National Park, Sri Lanka, in Dec. 2011. (Call of Large-billed Leaf Warbler also in the foreground of the recording).
Monosyllabic and disyllabic calls, and songs of the Green Warbler, recorded at Horton Plains National Park, Sri Lanka, in Nov. 2013.
Greenish Warbler’s vocalizations
Typical disyllabic calls of the Greenish Warbler, recorded at Thekkady, South India, in Oct. 2015.
Calls, including trisyllabic-like call, of the Greenish Warbler, recorded at Thekkady, South India, in Oct. 2015.
Calls and songs of the Greenish Warbler, recorded at Thekkady, South India, in Oct. 2015.