Friday, Aug 22, 2014

Mangrove Hummingbirds

Hummingbird Information


Mangrove Hummingbird (Amazilia boucardi)

The Mangrove Hummingbirds (Amazilia boucardi) can only be found in Costa Rica in Central America, where they are classified as endangered - with an estimated population of 2,500 to 10,000 birds.

Their numbers are declining due to the destruction of their mangrove habitat caused by the construction of Salinas and shrimp ponds, selective logging for charcoal production, illegal cutting, road construction and pollution.

Even though they primarily live in subtropical or tropical mangrove forests; they are occasionally seen in adjacent non-mangrove habitats.


Description

This medium-sized, mostly bronze and green hummingbird averages 9.5 - 11 cm in length (including its tail) and weighs around 4.5 grams. Its bill measures about 18 mm in length and is mostly straight except for a slight curve. The upper bill is blackish, while the lower bill is reddish in color.

The male's upper plumage is mostly bronze-green. The throat and chest are a glittering bluish-green. The feathers toward the chin have prominent white lines. The abdomen is whitish with bronze-green sides. The undertail feathers are whitish. The slightly forked tail is mostly bronzy-green.

The female is similar with a mostly white underplumage except for a little green spotting on the throat and sides. The female's outermost rectrices (flight feathers) have greyish tips.

Immature look like the female in throat coloration, and their under plumage is more greyish than that of the adults (Garrigues and Dean 2007, Ridgley and Gwynne 1989).

Similar Species:

The Mangrove Hummingbird resembles the Charming Hummingbird - except the bill of the Charming is straighter than that of the Mangrove Hummingbird. Also, the Charming has a violet-blue chest, while the Mangrove's is bluish-green (Garrigues and Dean 2007).

The female White-bellied Emerald is often confused with the female Mangrove, but the Mangrove Hummingbird has a mostly dark tail with bronze-green central long flight feathers, whereas the female White-bellied has a blacker tail and a greener chest  (Ridgley and Gwynne 1989).

Mangrove Hummingbirds can also be easily confused with the Snowy-breasted Hummingbird - which has an adjacent range yet not overlapping with that of the Mangrove. The males of both species are mostly green with a white abdomen. However, in the male Snowy-breasted Hummingbird, the contrast between the green throat and the white abdomen is clearer. Also, the Snowy-breasted 's tail is black, while the Mangrove's is bronzy green. In addition, the Snow-breasted 's rump is green to coppery green, while the Mangrove's is coppery bronze. (Ridgley and Tudor 1989). The bill of the Mangrove Hummingbird is also slightly larger than that of the Snowy-breasted.


Nesting / Breeding

Their breeding season usually stretches from October through February.

The female Mangrove Hummingbird alone constructs the cup-shaped nest using various plant fibers woven together. The nest structure is strengthenede with spider webbing and other sticky material, giving it an elastic quality to allow it to stretch to double its size as the young grow and require more space. The nest is lined with soft plant fibers, animal hair and feather down.

On the outside of the nest, she attaches green moss for camouflage. The nest is usually hidden in a shrub, bush or tree, where it is usually placed on a low, thin horizontal branch.

An average clutch consists of 2 white eggs, which are incubated by the female alone. The chicks are born blind, immobile and without any down.

The female alone protects and feeds the chicks with regurgitated food (mostly partially-digested insects since nectar is an insufficient source of protein for the growing chicks). The female pushes the food down the chicks' throats with her long bill directly into their stomachs.

As is the case with other hummingbird species, the chicks are brooded only the first week or two, and left alone even on cooler nights after about 12 days - probably due to the small nest size. The chicks leave the nest when they are about 7 - 10 days old.


Diet / Feeding

They primarily feed on nectar taken from a variety of brightly colored, scented small flowers of trees, herbs, shrubs and epiphytes - although favoring a flower known as the Tea Mangrove (Pelliciera Rhizophorae).

They use their long, extendible, straw-like tongues to retrieve the nectar while hovering with their tails cocked upward as they are licking at the nectar up to 13 times per second. Sometimes they may be seen hanging on the flower while feeding.

Many native and cultivated plants on whose flowers these birds feed heavily rely on them for pollination. The mostly tubular-shaped flowers actually exclude most bees and butterflies from feeding on them and, subsequently, from pollinating the plants.

They may also visit local garden nectar feeders for some sugar water, or drink out of bird baths or water fountains where they will either hover and sip water as it runs over the edge; or they will perch on the edge and drink - like all the other birds; however, they only remain still for a short moment.

They also take some small spiders and insects - important sources of protein particularly needed during the breeding season to ensure the proper development of their young. Insects are often caught in flight (hawking); snatched off leaves or branches, or are taken from spider webs. A nesting female can capture up to 2,000 insects a day.

Males establish feeding territories, where they aggressively chase away other males as well as large insects - such as bumblebees and hawk moths - that want to feed in their territory. They use aerial flights and intimidating displays to defend their territories.


Metabolism and Survival and Flight Adaptions - Amazing Facts


Calls / Vocalizations

Its call has been described as a soft, yet rapid, djt sound given in a descending twitter.


Species Research by Sibylle Johnson

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