Grey Nightjar (Caprimulgus jotaka) – Wildlife of Japan

Introduction

The Grey Nightjar (Caprimulgus jotaka), known as Yotaka in Japan, is a nocturnal bird inhabiting open forests and wooded lowlands across East Asia. Previously grouped within the Jungle Nightjar complex, it is now recognized as a distinct species with a breeding range extending from the Himalayas and China to Korea and Japan. In Japan, it arrives in spring as a summer visitor from Kyushu to Hokkaido and migrates to Southeast Asia in autumn. Its sharp, mechanical call is one of the defining sounds of summer nights in rural Japan.

Appearance

The Grey Nightjar measures about 29 cm in length and has a large head, short neck, long pointed wings, and a relatively long tail. Its plumage is a cryptic mix of gray, brown, and black markings that mimic dead leaves and bark, making a resting bird extremely difficult to detect.

Males show distinct white patches on the outer wings and white spots on the outer tail feathers. Females lack the bold white tail patches and instead show paler or buff-colored markings. The bill is small but opens widely, and fine bristles at the gape help the bird catch flying insects in midair.

Habitat & Distribution

Globally, the Grey Nightjar is found from the Himalayas through China and southeastern Russia to Korea and Japan, wintering mainly in Southeast Asia.

In Japan, the subspecies C. j. jotaka breeds as a summer visitor from Kyushu to Hokkaido. It favors open or semi-open forest habitats, including secondary broadleaf forests, young plantations, forest clearings, and sparsely vegetated slopes. Studies in Japan show that early-successional habitats—such as recently harvested plantation areas surrounded by forest—can be particularly important for this species.

Where to See in Japan

The species is usually detected by sound rather than sight, especially from late April to early summer.

Suitable areas include:

• Low hills and low mountains with a mosaic of forest and farmland
• Edges of secondary forests, young plantations, or clear-cut areas
• Forest roads at dusk, where birds may fly low while foraging
• Places with night lighting that attracts insects

These locations increase the likelihood of encounters but do not guarantee sightings, as the species is naturally elusive and has declined in many regions.

Behavior

The Grey Nightjar is crepuscular and nocturnal. During the day it rests motionlessly on the ground or along a branch, aligning its body lengthwise to enhance camouflage. After sunset it becomes active, flying with buoyant, twisting movements as it hunts flying insects.

The call is a rapid, mechanical series repeated for long periods from a perch within the territory.

Diet

The species feeds mainly on flying insects, including moths, beetles, flying ants, and other nocturnal insects. All prey is taken on the wing using its wide gape and bristle-fringed mouth.

Reproduction

In Japan, breeding occurs primarily from May to August. The Grey Nightjar does not construct a nest; the female lays two cryptically patterned eggs directly on bare ground, leaf litter, or gravel in open forest patches or along quiet forest tracks.

Because of the species’ excellent camouflage and nocturnal habits, detailed information on incubation behavior and parental roles remains limited for Japanese populations.

Conservation

Globally, the Grey Nightjar is listed as Least Concern. In Japan, however, long-term surveys show a marked decline since the late 20th century. It was listed as Vulnerable in the 2006 national Red List and is currently treated as Near Threatened. Many prefectural Red Data Books classify the species as Endangered, Vulnerable, or Near Threatened.

Major factors affecting the species include:

• Loss of early-successional habitats and open secondary forests
• Landscape changes in satoyama environments
• Development in former breeding areas
• Possible declines in large nocturnal insects (suggested but not yet well quantified)

Landscape-level studies suggest that maintaining a mosaic of young and mature forest stands may support stable populations.

Author’s Impression

The Grey Nightjar is usually very hard to find, but one night I was lucky enough to encounter one hunting along a quiet road and managed to photograph it. In the forest, its sharp, mechanical call echoing through the darkness is unforgettable. Moments like these highlight just how mysterious and special this nocturnal bird truly is.