Animal Spotlight: Uguisu

Taxonomy:images

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Aves
  • Order: Passeriformes
  • Family: Cettiidae
  • Genus: Cettia
  • Species: diphone
  • Also known as: Japanese Bush Warbler
  • Average Weight: 15g – 22g (0.5oz – 0.7oz)
  • Average Length: 14cm – 16.5cm (5.5in – 6.5in)
  • Average Wingspan 20cm – 22cm (7.9in – 9in)
  • Lifespan: 2-5 years

Known for its beautiful song, the Uguisu, also known as the Japanese bush warbler, is distributed throughout the Far East. While it is most common in regions throughout Japan where it is found all year round, populations exist in northeastern China, southern Russia, Korean peninsula, Taiwan, and northern Philippines.

This warbler can be found in mountainous regions at the varying altitudes of both lowland hills and high up in the mountain forests and bamboo thickets where there is plenty of foliage to hide amongst, along with an ample supply of food. They especially prefer bushes at a forest edge and in an open area of a forest. In recent years, they have more frequently bred in hills and lowlands probably because bushy habitat has increased in flood-controlled river basins and abandoned farmland.

Physical Description:

warbler
By Mitch Waite Group

A small-sized bird, the uguisu is known for it fairly dull coloration, particularly in comparison with the beauty of it’s song. They tend to be olive-green or light brown with darker plumage towards the tips of their wings and tail. Their underparts are normally beige. The plumage coloration varies slightly between the subspecies or the local populations.

Their tails are relatively long in relation to their body size and are comprised of straight feathers, making it similar in appearance to the long-tailed tits. Like other species of small perching bird, the uguisu also has thin legs with long, clawed toes to help them grip onto branches more easily. The warbler also has small dark eyes with pale stripes above each one and a straight, tan colored beak.

Diet:

Their diet is not well known but it is presumed that the uguisu shares a similar diet with other songbirds. They feed mainly on insects, such as flies, beetles, moths, and grasshoppers but they will also feed on worms, berries, and fruits to supplement its diet.

The need for food is one of the reasons why the uguisu migrate its natural environment.During the winter months, uguisu faces difficulties to find food in these conditions without compromise. Moving to the lowlands, there is a greater likelihood that food will not be so scarce.

Behavior:

The uguisu is a relatively solitary bird with individuals only interacting during the breeding season. During the winter months, they are fairly quiet with low chirping noises. But in early spring, they will break into song in order to try and attract a mate. Because of its solitary behavior, they are more often heard than seen by people.

In some areas, the uguisu are migratory birds flying between different countries with the changing seasons. This is most commonly to escape from the cold mountain winters, particularly on the large Japanese island of Hokkaido in the north. In other areas, such as the population in Mountain Tsukuba, central Japan, the same individuals are observed throughout the year. It is assumed that the populations of higher latitudes probably make a longer distance migration.

uguisu1

After mating, females will build a rugby ball-shaped nest with an opening on the side, using primarily dead leaves of bamboo grass. Usually, the nests are located in a low place in the bushes. Afterwards, they will lay four to six eggs, all of which are chocolate brown in color. After about 15 days of incubation, the hatchlings are fed and cared for by their mother until they fledged at around 2 weeks old. Fledgling rate is low, approximately 27%, largely due to predation.

Conservation and Threat:

This species has been listed on the IUCN Red List as ‘of least concern’ with very little imminent threat to its survival. This is because it’s range includes a number of countries at varying altitudes and habitats. Other than natural predation, population numbers in certain areas are stable, but numbers are declining in other regions, primarily due to deforestation, their biggest threat. They are also farmed 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 the Japanese bush warbler and do not have any conservation plans put in place.

Interesting Facts:

  • The uguisu was first described as a documented species by Heinrich von Kittlitz in 1830.
  • It is also known as the Japanese nightingale for its beautiful song, although it does not sing at night like a nightingale.
  • The uguisu is most closely related to other small songbirds including bushtits and nightingales, which they are similar in appearance too, although the uguisu is generally slightly larger.
  • Oddly enough, the droppings of the uguisu (known as guano) are now used as a product in certain face creams particularly, as it is thought to make skin softer and more radiant looking. This peculiar choice in moisturiser is thought to have been used by geishas and kabuki actors throughout Japan for centuries, and it is now sold as a commercial product.
  • The uguisu is seen as a sign of spring coming in Japan and is therefore also known by other names such as the Spring Bird and the Hanami Bird.
  • A group of warblers has many collective nouns, including a “bouquet”, “confusion”, “fall”, and “wrench” of warblers.

References + For More Reading

Uguisu

Japanese Bush Warbler

Field Guide to Birds of North America: Japanese Bush-Warbler

Japanese Bush Warbler · Horornis diphone

Cettia diphone (Japanese bush-warbler)

Data Zone: Japanese Bush-warbler Fact Sheet

Facts and Features of Uguisu

IUCN: Horornis diphone

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