Olive-backed Sunbird

About

The Olive-backed Sunbird, also known as the Yellow-bellied Sunbird, is a small passerine bird of the sunbird family Nectariniidae. It is widely distributed across Southeast Asia and northeastern Australia, known for its vibrant iridescent plumage in males and its active, nectar-feeding behavior. These birds are common residents in a variety of habitats, often found in gardens and urban areas.

Size & lifespan

Length

10-12 cm

Wingspan

13-15 cm

Weight

6-11 g

Lifespan

3-5 years in the wild

Diet

Nectarivore (primarily nectar, supplemented with small insects and spiders)

Physical characteristics

Plumage

Males have a metallic, iridescent blue-black throat and upper breast, contrasting with a bright yellow belly and olive-green back. The rump is also olive-green. Females lack the iridescent throat, having a duller olive-green head and upperparts, and a bright yellow underparts. Both sexes have a slender, decurved black bill and dark legs.

Beak shape

Long, slender, and decurved (downward-curved) black bill, adapted for probing into flowers.

Eye color

Dark brown

Leg color

Dark grey to black

Distinguishing features

The combination of a metallic blue-black throat/upper breast (male) or plain olive-green head (female) with a bright yellow belly and olive-green back is distinctive. Their small size and rapid, darting flight are also key features.

Juvenile appearance

Juveniles resemble adult females, but are generally duller, with a paler yellow belly and sometimes a faint streaking on the breast. Young males gradually acquire the iridescent throat patch as they mature.

Seasonal changes

No significant seasonal plumage changes. Plumage remains consistent throughout the year, though wear and tear can make colors appear slightly duller over time.

Sexual dimorphism

Pronounced. Males are much more brightly colored with iridescent blue-black on the throat and upper breast, while females are duller, lacking the iridescent patch and having an olive-green head.

How to identify

1. 1

   Size and Shape

   Small, slender bird with a long, thin, decurved bill. Often appears active and restless.

2. 2

   Male Plumage

   Look for the striking metallic blue-black throat and upper breast, contrasting sharply with the bright yellow belly and olive-green back. The iridescent patch can appear black in poor light.

3. 3

   Female Plumage

   Identify by the plain olive-green head and upperparts, and bright yellow underparts. Lacks any iridescent patches.

4. 4

   Behavior

   Observe its feeding habits: hovering or perching at flowers to sip nectar. Its rapid, darting flight is also characteristic.

5. 5

   Vocalizations

   Listen for its high-pitched, rapid, and often repetitive 'chew-chew-chew' song or sharp 'chip' calls.

Habitat & range

Biomes

Tropical and subtropical moist broadleaf forests, mangroves, shrublands, gardens, and urban areas.

Geographic range

Southeast Asia, including India (northeastern), Bangladesh, Myanmar, Thailand, Laos, Cambodia, Vietnam, Malaysia, Singapore, Indonesia, Philippines, Papua New Guinea, and northeastern Australia.

Elevation range

Sea level up to 1,800 meters, occasionally higher.

Preferred environments

Highly adaptable, preferring areas with abundant flowering plants, including coastal scrub, forest edges, plantations, parks, and residential gardens. They are often found in disturbed habitats.

Behavior

Activity time

Diurnal, most active during daylight hours, particularly in the morning and late afternoon.

Feeding habits

Primarily feeds on nectar, using its long, brush-tipped tongue to extract nectar from a wide variety of flowers. Also consumes small insects and spiders, especially when feeding young, which are caught on the wing or gleaned from foliage. They often hover briefly in front of flowers or perch while feeding.

Social behavior

Typically seen singly or in pairs, especially during the breeding season. Outside of breeding, they may form small, loose foraging groups. They are generally quite tame and accustomed to human presence in urban environments.

Flight pattern

Fast, direct, and often darting or hovering, especially when feeding at flowers. Their small size and rapid wingbeats give them a 'bee-like' flight.

Migration pattern

Resident throughout its range, with no significant migratory movements. Local movements may occur in response to flowering seasons or food availability.

Territoriality

Males can be territorial, especially during the breeding season, defending prime feeding areas and nesting sites from rivals. They will chase away other sunbirds and even larger birds.

Breeding & reproduction

Breeding season

Varies geographically, often coinciding with the availability of flowering plants. In many parts of its range, it can breed year-round, with peaks during the dry season or after monsoons.

Nesting habits

The female builds a distinctive pear-shaped or purse-shaped nest, suspended from a branch or leaf, often in a sheltered location like a porch or under a roof eave. The nest is constructed from fine grass, plant fibers, spider webs, and often decorated with bits of leaves, bark, or even rubbish, with a small side entrance.

Clutch size

2-3 eggs

Egg description

Typically 2-3 eggs, oval-shaped, whitish or pale greenish-blue, often speckled or mottled with brown or grey, particularly at the broader end.

Incubation period

13-14 days, primarily by the female.

Fledging period

13-16 days after hatching. Both parents feed the nestlings.

Parental care

Both parents participate in feeding the young, though the female does most of the incubation and initial brooding. Males are active in defending the nest and bringing food.

Where to find

Field tips

1. Look for flowering plants. Focus your search on areas with a variety of blooming flowers, as nectar is their primary food source. Hibiscus, bougainvillea, and banana flowers are often favored.
2. Listen for calls. Their high-pitched calls and songs are often the first indication of their presence, even before you see them.
3. Observe active feeding. They are very active feeders. Watch for small birds darting between flowers or hovering briefly to feed.
4. Check under eaves and sheltered spots. During breeding season, look for their distinctive hanging nests in sheltered locations around human habitation.

Similar species

Quick facts

Diet:

Nectar and small insects

Nest Type:

Pear-shaped hanging nest

Male Plumage:

Iridescent blue-black throat, yellow belly, olive back

Female Plumage:

Olive-green upperparts, yellow belly

Conservation Status:

Least Concern

Fun facts

• The Olive-backed Sunbird is one of the most common and widespread sunbird species in Southeast Asia and Australia.
• Despite their small size, they are quite aggressive and territorial, especially males defending their feeding patches.
• Their long, decurved bill and brush-tipped tongue are perfectly adapted for extracting nectar from deep flowers, similar to hummingbirds in the Americas.
• They are often seen 'robbing' nectar by piercing the base of flowers that are too deep for their bills, rather than entering through the opening.

Scientific classification

Kingdom

Animalia

Phylum

Chordata

Class

Aves

Order

Passeriformes

Family

Nectariniidae

Genus

Cinnyris

Species

Cinnyris jugularis

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