cetia japanese (Cettia diphone), also know as Japanese warbler, japanese bastard nightingale o Uguisu It is a songbird known for its beautiful song, common in the Asian continent. Although it is most common in regions throughout Japan, where it is found throughout the year


Six subspecies of Japanese cetia are recorded in Japan. Is about:

  • C. d. cantans widely distributed in the main islands of Japan.
  • C. d. diphone of the Ogasawara Islands.
  • C. d. riukiuensis.
  • C. d. restreined of the Nansei Islands.
  • C. d. sakhalinensis in the southern Kuril Islands.
  • C. d. borealis

But the classification is reconsidered now. C. d. restricta was discovered on the island of Minami-daitojima and has been considered extinct. However, in recent years, two types of Japanese cetia were observed on the island of Okinawajima and on the one that has characteristics of C. d. restricted. This subspecies is alive on the Amami and Ryukyu islands.

The other type observed on Okinawajima Island has characteristics of C. d. riukiuensis, and appears only in winter. Therefore, it probably breeds in the north of the country.

It is believed that C. d. riukiuensis is synonymous with C. d. cantans. and / or Cd sakhalinensis. Furthermore, the identification of C. d. sakhalinensis and C. d. cantans is unclear, although the former has more grayish plumage. These subspecies should also be reconsidered.


A small bird, the uguisu is known for its rather muted coloration, particularly compared to the beauty of its song. They tend to be olive green or light brown in color with darker plumage towards the wingtips and tail. Their underparts are normally beige. The plumage coloration varies slightly between subspecies or local populations.

Their tails are relatively long in relation to their body size and are made up of straight feathers, making them similar in appearance to long-tailed teats. Like other species of small perching birds, the uguisu also has slender legs with long, clawed toes to help them grip branches more easily. It also has small dark eyes with pale stripes on each of them and a straight, tan-colored bill.


The males sing a loud "Hoh, hokekyo" with the accent on the "ke" of the second syllable, and shout as "Pirrrrrr-kekkyo, kekkyo ...", which is called by the Japanese "Taniwatari (call crossing the valley) ». Males also sing the same song but in a whispering voice when courting females.

Females whisper "Chee, chee" softly during incubation and sing the one named by the people of Japan "Sasanaki (called bamboo grass) »in periods other than incubation and chicken rearing.

Male Japanese cetia also pronounce this "Sasanaki" in winter, but not in the breeding season.


Japanese cetia prefers shrubs on forest edges and open forest areas from the mountain belt to the area's subalpine forest, although they are widely distributed in a dense thicket of bamboo, grass, and shrubs from a coastal area to a region alpine.

In recent years, on the other hand, they have bred more frequently in hills and lowlands probably because shrub habitat has increased in flood-controlled river basins and abandoned farmlands.


Japanese cetia is distributed in Northeast China, the Russian Far East, the Korean Peninsula, and Japan.


The diet of the Japanese cetia is not well known, but it is presumed that the uguisu shares a similar diet with other songbirds. They feed primarily on insects, such as flies, beetles, moths, and grasshoppers, but they also eat worms, berries, and fruits to supplement their diet.

The need for food is one of the reasons why Uguisu migrate to their natural environment, and during the winter months they face difficulties finding food in these conditions without compromise. When moving to the lowlands, food is more likely to be less scarce.

The song of the Japanese cetia varies in name if it is male or female,

The song of the Japanese cetia varies in name if it is male or female,


The Japanese cetia has a large number of predators, such as cats and dogs, as well as snakes, lizards, and birds of prey.


The Japanese cetia has a polygynous mating system (a single male breeds with two or more females within the same territory). There is a record of a male mating with six females one after another in the same breeding season.

The females are in charge of building the nest, incubate the eggs and raise the young. Males try to attract as many females as possible by singing throughout the breeding season, regardless of the females' breeding stages. This is because males attempt to reproduce again with other females after they have successfully run away from their young or lost their eggs or chicks due to predation.

Although their mating system is polygyny, a male does not necessarily acquire two or more females at the same time, nor does a female mate with a single male in a breeding period.


They build a nest in the shape of a rugby ball with an opening on the side or on the upper side using mainly dead bamboo grass blades (Sasa spp.). The nest is often built low, such as in bushes.


They usually lay 4 to 6 eggs, which are chocolate brown in color.

Incubation and nesting periods

The incubation and nesting periods are approximately 15 and 13 days, respectively. The birth rate is low, roughly 27% due in large part to predation.

State of conservation

This species has been listed on the IUCN Red List as Least Concern (LC) with very little imminent threat to its survival. This is because its range includes several countries at different altitudes and habitats. Apart from natural predation, population numbers in some areas are stable, but are declining in other regions, mainly due to deforestation, their greatest threat.

They are also bred in Japan for their guano, which is used as a component in certain creams. For these reasons, IUCN and other conservation organizations do not focus their attention on it and have no established conservation plan.

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