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Monday, September 17, 2007

Purple-Throated Mountain-Gem, Costa Rica

The Purple-throated Mountain-gem (Lampornis calolaemus) is a hummingbird which breeds in the mountains of southern Nicaragua, northern Costa Rica and western Panama. It is replaced in southern Costa Rica by its close relatives, the White-throated and Gray-tailed Mountain-gems, with which it is sometimes considered conspecific. These three species form a closely-related group that evolved some 3.5 million years ago and has diversified since (GarcĂ­a-Moreno et al., 2006).

This bird inhabits forested areas in hilly terrain, and is found at altitudes from 800 m to 2500 m. It is 10.5 cm long. The male weighs 6.0 g and the female 4.8 g. The shortish black bill is slightly curved.

The adult male has bronze-green upperparts and underparts except for a brilliant green crown, purple throat and dark grey tail. The female lacks the bright crown and throat, and has rich cinnamon underparts. Young birds resemble the female but have buff fringes to the upperparts plumage.

The female Purple-throated Mountain-gem is entirely responsible for nest building and incubation. She lays two white eggs in a deep plant-fibre cup nest 0.7-3.5 m high in a scrub, small tree or vine. Incubation takes 15-19 days, and fledging another 20-26.

The food of this species is nectar, taken from a variety of small flowers, including epiphytic Ericaceae. Like other hummingbirds it also takes small insects as an essential source of protein. Male Purple-throated Mountain-gems defend flowers and scrubs in their feeding territories, and are dominant over most other hummingbirds. The call of this species is a sharp buzzy zeet.

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