In September 2017 during a long drought, 15 Horsfield’s Bronze Cuckoos were sitting on a powerline above a paddock in Priors Pocket in the west of Brisbane. The farmer had irrigated a patch of about a hectare of pasture for his cows in his battle against the drought. The surrounding habitat was typical for the species: an open-structured landscape with stands of trees and some undergrowth. What was not typical was that there were fifteen: they are normally seen singly or in small groups. So why were they there in such numbers?
Horsfield’s Bronze Cuckoo is the easiest of the bronze cuckoos to identify because of the broad line through the eye below a pale supercilium. It also has bright rufous at the base of the undertail, much stronger than other bronze cuckoos (except the Gould’s subsp. of Little), and also incomplete barring on the underparts, unlike the complete barring of the other two species. All three have bronze-green upperparts. Immature Horsfield’s can have a much weaker line through the eyes, making them more similar to immature Shining and Little Bronze Cuckoos, but they are usually not difficult to identify. One should also be aware of Black-eared Cuckoo, found almost exclusively west of the Divide. It has a much darker patch through the eye, and has grey upperparts, and is slightly larger.
The most frequently heard call is a series of long, descending high-pitched whistles. Each call lasts about a second, and each call is separated by about a second. One of the Shining Bronze Cuckoo’s calls is also a series of descending whistles, but these are much shorter with a very short gap between each call. Black-eared has a similar call to Horsfield’s, but is lower in pitch, and descends in pitch much less. It also has a similar call to another vocalisation of Horsfield’s, a short, rising and falling trill a little like an Australian Pipit. If you want to find Horsfield’s Bronze Cuckoo in Queensland, the best time is spring and early summer. Their calls are far-carrying, and sometimes continue for minutes on end, long enough for you to have a good chance to approach them to where they usually sit on an exposed perch. So once located, they are not hard to see.
Horsfield’s Bronze Cuckoos are very widespread across Australia, and in Queensland they are usually most common in the inland south but can occur anywhere in the state. They are less common east of the Divide and can fluctuate in numbers from year to year. Like the other bronze cuckoos in Australia, they are partial migrants, but in times of drought they are probably also nomadic. This species avoids closed forests, unlike Shining and Little Bronze Cuckoos, which prefer wetter habitats and thicker vegetation, while Shining Bronze Cuckoo is also found in rainforest. As partial migrants, though, they sometimes turn up in similar habitat to Horsfield’s. So these birds had sought out a patch of green where they could find a relative abundance of insects at a time when most of south-east Queensland’s paddocks and pastures were yellow or brown.
