Few birds carry a name as unsettling as the Diabolical Nightjar, also known as the Satanic Nightjar or Heinrich's Nightjar. It is a medium-sized, dark, exquisitely camouflaged nightjar found nowhere on Earth but the Indonesian island of Sulawesi. The German naturalist Gerd Heinrich collected the first known specimen, a single female, on the slopes of Mount Klabat in northern Sulawesi in 1931. For most of the twentieth century that lone bird was all science had. No one reliably saw another, and the species drifted into a kind of ornithological folklore, a name on a list attached to almost no field knowledge.
Its sinister reputation comes from a local story. Villagers spoke of a nocturnal sound, a soft plop, said to be the noise of a creature plucking out the eyes of sleepers, and the scientific epithet diabolicus nods directly to that legend. When the bird was finally relocated in the 1990s and its odd, liquid two-note call recorded and matched to the myth, one of the great mysteries of Indonesian ornithology was quietly solved. Even now, though, it remains among the least-known nightjars in the world, and shrinking montane forest keeps it listed as Vulnerable.
On Sulawesi, range and voice do most of the identification work: this is the island's only Eurostopodus eared-nightjar, and it is far more often heard than seen. It is a dark, cryptically patterned bird of the forest floor and night sky. Field observations remain scarce, so most descriptions lean on the handful of specimens and a small number of well-documented sightings. Look for the buff hindneck collar, pale scapular markings, and small white flashes in the outer wing when a bird is caught in a spotlight beam at dusk.
| Size | Medium nightjar, roughly 27 cm long, with a large flat head |
| Plumage | Dark greyish-brown overall, finely vermiculated and spotted for camouflage |
| Collar | A distinct buff or tawny band across the hindneck |
| Upperparts | Pale scapular patches breaking up an otherwise dark, mottled back |
| Wings | Small white spots on the outer primaries, flashing in flight or under a lamp |
| Habits | Strictly nocturnal; roosts motionless on the ground or a low branch by day |
Male vs. female
The sexes of the Diabolical Nightjar are poorly known and, as far as the limited material shows, look broadly similar. In many nightjars males carry more prominent white spots or panels in the wings and tail than females, but for this species the differences have never been clearly documented in the field. The 1931 type specimen was a female, and the small number of subsequent records has not built up a reliable picture of male versus female plumage. Honestly, this is a bird where the standard "how to sex it" advice simply does not yet exist, and any confident claim of a difference should be treated with caution.
Juveniles
The appearance of young Diabolical Nightjars is essentially undescribed. No nest, egg, or dependent chick of this species has been documented in the scientific literature in any detail, so there is no reliable account of downy young or juvenile plumage. By analogy with better-studied nightjars, newly hatched chicks would be covered in cryptic down and able to shuffle a short distance from the nest scrape within days, and juveniles would resemble a duller, softer-patterned version of the adult. All of that, however, is inference from relatives rather than observation of this bird.
The voice is the key to the whole story. Instead of the dry churring or trilling many people associate with nightjars, the Diabolical Nightjar gives a clear, liquid two-note phrase, usually rendered as a soft plip-plop or ploop, with the second note lower and fuller, like a drop of water falling into a pool. Birds call from perches or in flight through the night, the notes carrying well through humid forest and repeating at intervals.
It was precisely this strange, un-nightjar-like sound that fed the eye-plucker legend, and it was the same sound, tape-recorded and analyzed in the 1990s, that let researchers confirm the species still survived and begin locating it. To this day the call is the most practical way to detect the bird, since seeing one well is a matter of luck and a good spotlight.
The Diabolical Nightjar is endemic to Sulawesi, the large, oddly shaped island at the heart of Indonesia's Wallacea region. Confirmed and probable records come from the northern peninsula, where the type specimen was taken on Mount Klabat, and from central Sulawesi, notably in and around Lore Lindu National Park. Its true distribution is still being pieced together, and it may prove more widespread than the sparse record suggests simply because so few observers spend nights listening in the right forests.
It occupies moist forest across a wide elevation band, with records spanning roughly 250 to over 2,300 metres, taking in both lower hill forest and cooler montane forest. Birds have been noted around forest edges, clearings, and lightly disturbed areas as well as closed forest, hunting in the open airspace above and between the trees. Because Sulawesi sits in the humid equatorial tropics, there is no strong migratory pattern; the species is presumed resident year-round wherever suitable forest remains.
Like all nightjars, the Diabolical Nightjar is an aerial insectivore, catching flying insects on the wing in the dark. Its diet has not been studied directly, but by the standards of the family it almost certainly takes moths, beetles, and other night-flying insects, snapping them up in its wide, bristle-fringed gape during sallying flights. Observers have reported birds foraging over clearings, forest gaps, and the canopy, where insects concentrate.
Beyond that broad picture, the specifics remain guesswork. No detailed analysis of stomach contents or prey selection has been published, and there is little information on whether it favors particular insect groups, hunting heights, or times of night. As with much of this bird's life, what we "know" about its feeding is largely extrapolated from its well-studied relatives rather than measured in the field.
The breeding biology of the Diabolical Nightjar is effectively a blank page. No nest has been formally described, and details of its eggs, incubation, and chick-rearing are unknown to science. Nightjars as a group do not build nests; they lay directly onto bare ground, leaf litter, or rock, relying on the sitting adult's superb camouflage rather than any structure for protection, and most eared-nightjars lay just a single egg per attempt.
On that basis the Diabolical Nightjar is presumed to lay a single, well-camouflaged egg on the forest floor, with the incubating adult sitting tight and trusting to its cryptic plumage. The number of broods, the length of incubation, and the roles of the sexes are all undocumented. This gap is a real one: a genuinely described nest of this species would be a notable ornithological find.
This is not a backyard bird, and there is no way to draw it to a garden. For anyone hoping to encounter one, the realistic goal is a well-planned night in the right Sulawesi forest, with modest but genuine odds if you go prepared and patient.
- Focus on Lore Lindu National Park in central Sulawesi, the most consistent area for the species and a hub for birders targeting Sulawesi endemics.
- Search in hill and montane forest, anywhere from the lower slopes up to around 2,000 metres, favoring forest edges, clearings, and openings where nightjars hunt.
- Go out at dusk and after dark, when the birds become active; a strong spotlight or head-torch is essential for turning a calling bird into a sighting.
- Learn the call first, that liquid plip-plop is the single most reliable way to detect the bird, so listen to recordings before you travel.
- Consider the drier months, roughly June to September, when nights are more settled and forest access is easier, though the resident birds can call year-round.
- Hire a local bird guide, someone who knows current territories and trails will hugely improve your chances and reduce disturbance to the birds.
- Great Eared Nightjar: A much larger eared-nightjar of Asian forests with prominent ear-like tufts and a churring, whistled voice.
- Sulawesi Nightjar: A smaller nightjar sharing the same island but with a different, more typical churring voice and pattern.
Why is it called the Diabolical or Satanic Nightjar?
The names trace back to Sulawesi folklore about a nocturnal creature whose soft, dripping call was said to signal that it was plucking out the eyes of sleeping people. The scientific epithet diabolicus captured that eerie reputation, and the English names followed.
Is the Diabolical Nightjar really that rare?
It is genuinely uncommon and restricted to Sulawesi, and it is listed as Vulnerable because of its small range and forest loss. Part of its mystique, though, comes from being nocturnal and easily overlooked, so it may be somewhat more numerous than the thin record of sightings suggests.
How was it rediscovered after 1931?
Following the single female collected on Mount Klabat in 1931, the species went essentially unrecorded for decades. In the 1990s researchers finally relocated it and recorded its distinctive whistled call, matching the sound to the old legend and confirming the bird still survived.
Where is the best place to look for one?
Sulawesi in Indonesia, especially Lore Lindu National Park in the center of the island. It is a bird of hill and montane forest, active after dark, so a night walk with a guide, a spotlight, and knowledge of its call gives the best chance.
What does its call sound like?
Unlike the dry churring of many nightjars, it gives a clear, liquid two-note phrase often written as a soft plip-plop, the second note lower and fuller, like a drop of water falling. This unusual sound is both the source of its legend and the main way surveyors find it.
Why do we know so little about this bird?
It is nocturnal, cryptically camouflaged, and confined to forests on one Indonesian island that few ornithologists visit at night. Its nest and eggs have never been formally described, and most of what is written about its diet and breeding is inferred from better-studied relatives rather than observed directly.