Chestnut-bellied hummingbird  (Amazilia castaneiventris)

Classified as Endangered (EN) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

The wonderfully vibrant chestnut-bellied hummingbird has a glittering golden-green throat and chest, and bronze-green upperparts (2). As its common name suggests, the belly is a chestnut colour that extends to the tail, and fades to buff on the rump (2) (4). This small hummingbird has a straight, medium-sized, blackish bill, with a red base, while inconspicuous white feathers give the legs a ‘fluffy’ appearance (2) (4). The female is similar to the male, but somewhat duller, with a paler belly and barring on the upper throat feathers. Juveniles lack the bright colouration of adults and have a reddish-brown tinge to the throat feathers (2). 

Endemic to Colombia, the chestnut-bellied hummingbird has a fragmented distribution across the western slope of the East Andes, and the Serranía de San Lucas. As the species has been largely unrecorded over recent decades, its exact distribution is unclear, but it is known to occur in around 15 locations through the Departments of Bolivar, Santander and Bojacá (4).

The chestnut-bellied hummingbird is typically found in dry forested valleys with bushes and low trees, between 850 and 2,200 metres above sea level (5). It is also relatively tolerant of habitat degradation, and has been recorded in fruit and coffee plantations, and agricultural pastures (4).

The diminutive hummingbirds display remarkable manoeuvrability in flight, capable of hovering whilst feeding, with up to 200 wing beats per second. Owing to this energy-demanding behaviour, hummingbirds feed almost exclusively on nectar, the carbohydrate-rich sugar secretions of plants, feeding from as many as 1,000 to 2,000 flowers each day. Hummingbirds also have the highest oxygen requirement of any vertebrate and, as a result, have uniquely structured lungs that enable them to breathe at a rate of up to 500 breaths per minute. These physiological adaptations have allowed hummingbirds to occupy a vast array of habitats and altitudes throughout the Americas (6). 

A little studied species, the biology of the chestnut-bellied hummingbird remains largely unknown. However, this tiny bird is thought to feed from the flowers of several plant species, including Salvia  and Trichanthera, using its long, specialised tongue to collect nectar from the bottom of the nectaries (2). Breeding pairs form between August and December and, in common with other hummingbirds, males will attract partners with elaborate courtship displays (2) (6). It is also likely that males are territorial and will vigorously defend their home range from intruders (6). Males may mate with several females, but females are responsible for incubating the clutch of two eggs and raising the offspring (2) (6). Once fledged, the young birds may remain fairly sedentary, or undertake nomadic movements in response to seasonal fluctuations in water availability and flowering in key plant species (4).

Inhabiting a region with a large human population and intensive agriculture, the chestnut-bellied hummingbird is suffering from extensive habitat loss. The status of this species has been somewhat unclear, having been unrecorded over recent decades, but it is now obvious that this rare species occupies a vulnerable position in a number of small, fragmented populations (4). Deforestation has become progressively prevalent in the Colombian Andes, with large tracts of forest replaced by coffee and sugarcane plantations, pasture and crop cultivation (5) (7). Mining activity, largely stimulated by a gold rush in 1996, has also had negative effects on the environment, through habitat loss, pollution and increased human immigration (4) (7).

Fortunately for the chestnut-bellied hummingbird, it is the target of numerous conservation measures. Since 2002, the Colombian conservation organisations Fundación Colibri, Organizacion Ambiental Ocotea and Fundacion Ecodiversidad have been directing community involvement projects in a reserve that supports the species. In 2008, they also began a banding and nest monitoring scheme, and have undertaken awareness campaigns involving school children (8). Furthermore, Fundación ProAves, in collaboration with the Amercian Bird Conservancy, have successfully created the Pauxi Pauxi reserve and the Cerulean Warbler Reserve, and are working to protect the forests there (9). The chestnut-bellied hummingbird is also afforded sanctuary in the newly established Chicamocha National Park (4).

View information on this species at the UNEP World Conservation Monitoring Centre.

For more information on the conservation of the chestnut-bellied hummingbird, see:

• The American Bird Conservancy: 
  http://www.abcbirds.org/abcprograms/international/action/pauxi.html
• Fundación ProAves: 
  http://www.proaves.org/sommaire.php?lang=en

For more information on this and other bird species please see:

• BirdLife International:
  http://www.birdlife.org