Brush Cuckoo

Brush Cuckoo The Secretive Nest Parasite of Australia’s Rainforests

In days gone by, the lush rainforests of eastern Australia were often referred to as ‘brushes’ or ‘big scrubs,’ hence the origin of the Brush Cuckoo’s name. The esteemed Australian ornithological book, “What Bird is That?” by Cayley, still dedicates a section to the ‘Birds of the brushes and scrubs.’

The Brush Cuckoo Cacomantis variolosus is typically found in the more humid locales of eastern and northern Australia, gracing the edges of rainforests, mangroves, riverside vegetation, and monsoon forests, though it tends to avoid the drier, inland areas.

Some folks might find it a tad challenging to tell the Brush Cuckoo apart from its cousin, the Fan-tailed Cuckoo. The Brush Cuckoo sports a rather plain appearance, with a shorter tail and fewer white markings compared to the Fan-tailed. The most noticeable difference lies in the eye-ring colour – bright yellow for the Fan-tailed, while the Brush Cuckoo’s is a modest grey or pale yellow.

Their calls are quite distinctive too, if you listen carefully.

Did you know?
The Brush Cuckoo possesses a remarkable ability to lay eggs that mimic the colour and size of the host bird’s eggs – a cool feat of nature’s mimicry.

In the eastern regions, Brush Cuckoos are migratory, arriving in late September and departing at different times depending on the location. In contrast, the northern Australian birds are considered a separate subspecies and are generally resident.

These cuckoos often parasitise birds that build open nests, such as honeyeaters, robins, flycatchers, and fantails, and occasionally fairy-wrens and gerygones.

Description

The male Brush Cuckoo dons a grey-brown coat above and a light grey to buff belly, with a grey head, neck, and breast. Its tail finishes with a white tip and is barred in white underneath. The female can appear in two forms: unbarred and barred. The unbarred morph resembles the male but is a lighter buff below, with faint grey barring across the chest. The barred morph is less common, featuring streaked or barred upper parts and a darkly barred underbody. Juveniles are heavily barred dark brown above and mottled with bars underneath.

This bird serenades with a series of descending, loud whistled notes, often sounding like ‘fear-fear-fear-fear.’ It also has a distinct three-note call that seems to ask, ‘where’s-the-tea?’

Similar Species

The Brush Cuckoo shares a similar shape with the Pallid Cuckoo, C. pallidus, but boasts more buff underparts. The Fan-tailed Cuckoo, C. flabelliformis, is more slate-grey on the back with a yellow eye-ring and a longer, more fanned tail, while the Chestnut-breasted Cuckoo, C. castaneiventris, displays a rich chestnut hue on the underbody.

Distribution

The Brush Cuckoo is found across the northern expanse of Australia, stretching from the Kimberley region to the east coast, reaching down to Victoria. Its range also includes eastern Indonesia, such as Timor and the Moluccas, as well as New Guinea and the Solomon Islands.

Habitat

This bird thrives in wooded habitats, including rainforests, wet sclerophyll forests, paperbarks, along waterways, and in more open forests and woodlands. Occasionally, it even graces gardens with its presence.

The Brush Cuckoo is partially migratory, with southern populations migrating northward during winter.

Diet

The Brush Cuckoo’s diet consists mainly of insects, particularly hairy caterpillars. It usually forages high in the forest canopy but may occasionally venture to the ground for a meal.

Breeding

A nest parasite by nature, the Brush Cuckoo lays its eggs in the nests of other birds. Its preferred hosts include flycatchers, particularly Rhipidura species, robins, fairy-wrens, gerygones, and honeyeaters. In northern Australia, the Brown-backed and Bar-breasted Honeyeaters are common hosts, while in the south, the Grey Fantail, Scarlet Robin, and Leaden Flycatcher are typically chosen. The cuckoo lays just one egg per host nest, with its egg closely resembling the host’s in markings. Once hatched, the young cuckoo ousts any other eggs or chicks. The unwitting host parents continue to care for and feed the young cuckoo, sometimes for up to a month after it fledges.