Asian Koel

About

The Asian Koel is a large, long-tailed cuckoo found across Asia. It is a brood parasite, laying its eggs in the nests of other birds, primarily crows. Known for its distinctive, loud calls, especially during the breeding season, it is often heard more than seen.

Size & lifespan

Length

39-46 cm

Wingspan

Approximately 55-65 cm

Weight

190-327 g

Lifespan

Approximately 5-8 years in the wild

Diet

Omnivore, primarily frugivorous, but also consumes insects, caterpillars, eggs, and nestlings of host birds.

Physical characteristics

Plumage

Adult male is glossy bluish-black or greenish-black all over. Adult female is dark brown on the crown and upperparts, heavily spotted and barred with white or buff. The underparts are paler, buffy-white, also heavily barred with dark brown. Juveniles resemble females but are duller and have a blackish beak.

Beak shape

Stout, slightly decurved, and conical. Adult males have a pale greenish-yellow to yellowish-green beak, sometimes with a reddish tinge at the base. Females and juveniles have a blackish beak.

Eye color

Bright crimson red in adults, dark brown in juveniles.

Leg color

Greyish-black to dark grey

Distinguishing features

The striking red eyes of adults, the glossy black plumage of the male, and the heavily spotted and barred plumage of the female are key features. Its large size and long tail are also distinctive.

Juvenile appearance

Juveniles are duller than adult females, with a blackish beak and dark eyes. They have a similar spotted and barred pattern but are generally less contrasting.

Seasonal changes

No significant seasonal plumage changes in adults. Plumage remains consistent year-round.

Sexual dimorphism

Pronounced sexual dimorphism, with males being entirely glossy black and females being brown with extensive white/buff spotting and barring.

How to identify

1. 1

   Male Plumage

   Look for a large, entirely glossy bluish-black bird with striking red eyes and a pale greenish-yellow bill. Its long tail is also noticeable.

2. 2

   Female Plumage

   Identify by its dark brown upperparts heavily spotted and barred with white/buff, paler underparts with similar barring, red eyes, and a blackish bill. The overall impression is a heavily patterned bird.

3. 3

   Vocalization

   Listen for the loud, repetitive, ascending 'ko-EL, ko-EL' call of the male, especially at dawn and dusk. The female's sharp 'kik-kik-kik' is also distinctive.

4. 4

   Behavior

   Observe its arboreal habits, often moving stealthily through dense foliage. Its presence is often revealed by its calls or by the agitated behavior of host crows.

5. 5

   Habitat

   Look in areas with fruit-bearing trees, especially figs, in gardens, parks, and woodlands, often near human habitation where host crows are common.

Habitat & range

Biomes

Tropical and subtropical forests, woodlands, groves, orchards, gardens, and urban parks.

Geographic range

Widespread across the Indian subcontinent, Southeast Asia, China, and extending to Australia (where it is known as the Eastern Koel, Eudynamys orientalis, often considered a separate species or subspecies group).

Elevation range

Sea level up to approximately 1,800 meters.

Preferred environments

Prefers areas with abundant fruit-bearing trees, especially figs, and the presence of host bird species (primarily crows) for brood parasitism. Often found in human-modified landscapes.

Behavior

Activity time

Diurnal, most active during early morning and late afternoon, especially vocal during these periods.

Feeding habits

Primarily arboreal, feeding on fruits, especially figs, berries, and other soft fruits. Also consumes insects, caterpillars, and occasionally eggs or nestlings of host birds. Forages stealthily among foliage.

Social behavior

Generally solitary or found in pairs during the breeding season. Not typically seen in large flocks.

Flight pattern

Strong, direct flight with rapid wing beats, often undulating. Can be quite agile when navigating through dense canopy.

Migration pattern

Many populations are migratory, particularly those in northern parts of their range (e.g., China, northern India), moving south for winter. Southern populations (e.g., peninsular India, Southeast Asia) are largely resident or undertake local movements. Australian populations are migratory, breeding in Australia and migrating to New Guinea and Indonesia for the non-breeding season.

Territoriality

Males are territorial during the breeding season, defending calling perches and areas where host nests are likely to be found. Calls are often used to establish and maintain territory.

Breeding & reproduction

Breeding season

Varies geographically, typically coinciding with the breeding season of its host species. In India, generally April to August; in Southeast Asia, March to July.

Nesting habits

Obligate brood parasite. Does not build its own nest. Females lay eggs in the nests of other bird species, primarily corvids (crows, magpies), but also sometimes bulbuls, babblers, and shrikes. The female typically removes one host egg before laying her own.

Clutch size

A female koel may lay multiple eggs in different host nests over a breeding season, usually one egg per host nest.

Egg description

Eggs are typically pale greenish-grey to olive-brown, often with reddish-brown spots or blotches, resembling the eggs of its host species (e.g., House Crow). They are relatively small for the size of the koel.

Incubation period

Approximately 12-14 days, similar to that of its crow hosts. Incubation is performed by the host parents.

Fledging period

Koel chicks fledge around 20-28 days after hatching, often staying in the host's territory and being fed by host parents for several weeks post-fledging.

Parental care

No parental care from the biological parents. The host parents incubate the egg, feed the chick, and raise it until independence. The koel chick often outcompetes or ejects host chicks/eggs.

Where to find

Field tips

1. Listen for Calls. The Asian Koel is often heard before it is seen. Learn its distinctive calls, especially the male's 'ko-EL' song, and locate it by sound. They are most vocal during the breeding season.
2. Look in Fruit Trees. Scan fruit-bearing trees, particularly fig trees, as these are a primary food source. They can be well-camouflaged among the leaves.
3. Observe Host Birds. Pay attention to the behavior of crows. Agitated crows mobbing a bird might indicate the presence of a koel, as crows often harass koels due to their brood parasitic nature.
4. Dawn and Dusk. These are the most active and vocal times for Asian Koels, making them easier to detect.

Similar species

Quick facts

Primary Diet:

Fruits (frugivorous)

Nesting Strategy:

Obligate brood parasite

Host Species:

Mainly crows (Corvidae)

Distinctive Feature:

Loud, repetitive 'ko-EL' call

Eye Color:

Bright crimson red in adults

Fun facts

• The Asian Koel's scientific name 'Eudynamys' means 'true powerful one', referring to its loud voice.
• In many cultures, the call of the Asian Koel is associated with the arrival of spring or the monsoon season.
• Despite being a brood parasite, the koel chick does not always eject host eggs or chicks, sometimes growing up alongside them, though it usually outcompetes them for food.
• The female koel is known to observe host nests for suitable egg-laying opportunities, often waiting for the host to be absent.

Scientific classification

Kingdom

Animalia

Phylum

Chordata

Class

Aves

Order

Cuculiformes

Family

Cuculidae

Genus

Eudynamys

Species

Eudynamys scolopaceus

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