The Bluish Flowerpiercer (Diglossa caerulescens) is a smaller lighter dullish blue bird with black lores, black orbital rings and whitish grey vent and belly. A notable field mark of this bird is the intense reddish orange color in the eyes. Its bill is thin and slightly conical until the tip, where on the upper mandible it has a hooked protrusion bending down. However, this protrusion is not as big as seen on the bills of other members of Diglossa (Hilty 2003). Some researchers previously placed the Bluish Flowerpiercer in the genus Diglossopis (Restall et al 2007)
The Bluish Flowerpiercer is commonly confused with the Masked Flowerpiercer (Diglossa cyanea) due to many similar features. Both species have mostly blue plumage with black lores, although the Masked Flowerpiercer’s plumage is more vibrant in color (Hilty 2003). The songs of the two species are also similar, except the Bluish Flowerpiercer’s song is a quick series of separated chirps. The Masked Flowerpiercer’s song begins in a similar manner but ends in a chirp-like trill for 2 or 3 seconds.
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Tanagers that have been studied have either a Complex Basic Strategy or Complex Alternative Strategy (Ryder and Wolfe 2009). However, most tanagers only molt once a year (Isler and Isler 1987), and this prebasic molt likely occurs after the breeding season (Isler and Isler 1987, Ryder and Wolfe 2009). Although a juvenile plumage is described for the Bluish Flowerpiercer (Restall et al. 2007), more specific information on molt and its timing is not available for this species.
Eyes: orange or dark-red eyes (Hilty and Brown 1986)
Upper and lower mandible: black with streaks of faint yellow (Restall et al. 2007).
Legs and feet: black (Restall et al. 2007).
Length: 13 cm Mass: 13 g (10.1-16.0 g, n=27) (Isler and Isler 1987).