The Crimson Sunbird, Aethopyga siparaja, is a diminutive yet striking bird, measuring a mere 11 cm in length. The adult male is resplendent with a crimson breast and a maroon back, set off by black malar stripes. A vibrant yellow rump and olive belly complete its palette. The female, in contrast, sports an olive-green back and a yellowish breast, with white tips adorning the outer tail feathers.
To identify the Crimson Sunbird, look for the male's distinctive coloration—crimson and maroon with a yellow rump. Females are more subdued in color but can be recognized by their olive-green back. The species is characterized by medium-length, thin, down-curved bills and brush-tipped tubular tongues, specialized for nectar feeding. In most of their range, males boast a long green-blue tail, though some regional variations exist.
This species is known to inhabit both forests and cultivated areas, demonstrating a degree of adaptability to human-altered landscapes.
The Crimson Sunbird is a resident breeder across tropical southern Asia, with its range extending from India and Nepal through Bangladesh and Myanmar to Indonesia and Brunei.
These sunbirds exhibit fast and direct flight on their short wings. While they are capable of hovering like hummingbirds to take nectar, they more commonly perch to feed. They are also known to consume insects, particularly when provisioning their young.
The call of the Crimson Sunbird is a distinctive "chee-cheewee," a sound that once heard, is not easily forgotten.
The Crimson Sunbird lays two or three eggs in a nest that is suspended within a tree, a testament to their architectural ingenuity.
While the Crimson Sunbird is unique in its coloration, it may be confused with other sunbird species. However, the long green-blue tail of the male is a helpful distinguishing feature.
Primarily nectar feeders, Crimson Sunbirds have evolved bills and tongues ideally suited for this diet. They do, however, supplement their diet with insects, a necessary protein source during the breeding season.
The Crimson Sunbird is currently classified as Least Concern by the IUCN, indicating a stable population without immediate threats to its survival.