The tesias are a genus, ''Tesia'', of

Old World warbler The Old World warblers are a large group of birds formerly grouped together in the bird family Sylviidae. They are not closely related to the New World warblers. The family held over 400 species in over 70 genera, and were the source of much taxo ...

. Though once included in the large

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Sylviidae Sylviidae is a family of passerine birds that includes the typical warblers ''Sylvia'', and closely related genus '' Curruca'', formerly included in ''Sylvia''. They are found in Eurasia and Africa, with the greatest diversity in the Mediterrane ...

, more recent research placed it within a new family,

Cettiidae Cettiidae is a newly validated family of small insectivorous songbirds (" warblers"), formerly placed in the Old World warbler "wastebin" assemblage. It contains the typical bush warblers ('' Cettia'') and their relatives. As a common name, cet ...

. The four species inhabit undergrowth of

montane forest Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures lapse rate, fall as elevation increases, causing the ecosystem to stratify. This stratification is ...

South South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both west and east. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþa ...

and

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

, where they are resident or short-range migrants. They have longish legs and appear tailless, with (seemingly) only 8 rectrices. Their simple songs are fairly loud, and their nests are typically ball-shaped. Their name is derived from ''Tisi'', the Nepalese name for the grey-bellied tesia (''Tesia cyaniventer'').

Taxonomy

The genus ''Tesia'' was erected in 1837 by the English naturalist

Brian Houghton Hodgson Brian Houghton Hodgson (1 February 1801 – 23 May 1894) was a pioneer natural history, naturalist and ethnologist working in India and Nepal where he was a British Resident (title), Resident. He described numerous species of birds and mammals fr ...

. The name is from the Nepalese word ''Tisi'' for the grey-bellied tesia. The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

was designated as the grey-bellied tesia (''Tesia cyaniventer'') by the English zoologist

George Robert Gray George Robert Gray (8 July 1808 – 6 May 1872) was an English zoology, zoologist and author, and head of the Ornithology, ornithological section of the British Museum, now the Natural History Museum, London, Natural History Museum, London f ...

in 1847. The chestnut-headed tesia was formerly included in the genus. A

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

study published in 2011 found that the chestnut-headed tesia was embedded in a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

containing members of the genus ''

Cettia ''Cettia'' is a genus of small insectivorous songbirds ("warblers") which make up the core of the newly recognized family Cettiidae. They were formerly placed in the Sylviidae, which at that time was a wastebin taxon for the warbler-like Sylv ...

''. The species was therefore moved but retained the same common name.

Range and diversity

The genus has a disjunct distribution in South and South East Asia. The three northern species range widely across southern China, Burma, Northern Thailand and Laos and into India, southern Nepal and Vietnam; whereas the other two species are found in

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

and the

Lesser Sundas The Lesser Sunda Islands (, , ), now known as Nusa Tenggara Islands (, or "Southeast Islands"), are an archipelago in the Indonesian archipelago. Most of the Lesser Sunda Islands are located within the Wallacea region, except for the Bali pr ...

in southern

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

. The russet-capped tesia was once considered to be a race of the Timor stubtail, ''Urosphena subulata''. The three northern species are sometimes known as ground-warblers.

Description

Tesias are tiny ground-living warblers which range in length from 7 to 10 cm and weigh between 6 and 12 g.Franz Bairlein, Per Alström, Raül Aymí, Peter Clement, Andrzej Dyrcz, Gabriel Gargallo, Frank Hawkins, Steve Madge, David Pearson & Lars Svensson "Family Sylviidae (Old World Warblers)" ''in'' del Hoyo, J.; Elliot, A. & Christie D. (editors). (2006). ''

Handbook of the Birds of the World The ''Handbook of the Birds of the World'' (HBW) is a multi-volume series produced by the Spanish publishing house Lynx Edicions in partnership with BirdLife International. It is the first handbook to cover every known living species of bird. ...

.'' Volume 11: Old World Flycatchers to Old World Warblers. Lynx Edicions. . They have long legs and an upright stance, and appear to almost lack a tail, as their tail rectrices are shorter than the tail coverts.Captain J. Delacour (1942) "The Bush-Warblers of the Genera Cettia and Bradypterus, with Notes on Allied Genera and Species". ''Ibis'' 84 (4): 509-519, The

plumage Plumage () is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, there can b ...

of the northern species is olive backs and wings and grey bellies (darker slate in the slaty-bellied tesia); the southern species have brown wings and backs. All species have an eye-stripe and all except the slaty-bellied tesia have a

supercilium The supercilium is a plumage feature found on the heads of some bird species. It is a stripe which runs from the base of the bird's beak above its eye, finishing somewhere towards the rear of the bird's head.Dunn and Alderfer (2006), p. 10 Also k ...

; this is most prominent in the Javan tesia. The plumage of the chestnut-headed tesia is different from the other species; it has a bright yellow belly, chest and throat, and a deep chestnut coloured head and an incomplete white orbital ring. It lacks the facial stripes of the other species. The

bill Bill(s) may refer to: Common meanings * Banknote, paper cash (especially in the United States) * Bill (law), a proposed law put before a legislature * Invoice, commercial document issued by a seller to a buyer * Bill, a bird or animal's beak Pl ...

of all species is long and bicoloured, with a dark upper mandible and a flesh-coloured lower one, as well as strong ridge on the upper mandible.

Habits

Tesias live in the undergrowth of forest, usually montane broadleaf forest. They have a preference for damp forest, and are often found near water, particularly the Chestnut-headed and slaty-bellied tesias, although they use a range of microhabitats within the forest, including patches of bamboo or nettles. The three northern species are altitudinal

migrants Migrant is a term that may refer to: Human migration *Human migration, including: **Emigration, leaving one's resident country with the intent to settle elsewhere. 1988 Webster's Definition. One who migrates, esp. from 1 region to another in sear ...

, breeding up to 4,000 m but wintering as low as 150 m. The two southern species are resident within their range. The tesias are active insectivores that usually feed near the ground amongst the undergrowth and leaf litter, but may forage as high as 25 m off the ground (in the case of the russet-capped tesia) amongst the tangle of creepers on large tree trunks. The slaty-bellied tesia will move leaves around in the manner of a

thrush Thrush may refer to: Birds * Thrush (bird), any of the birds in the family Turdidae ** List of thrush species * Antthrushes, the Formicariidae family of birds * Dohrn's warbler, or Dohrn's thrush-babbler, a species ''Sylvia dohrni'' in the famil ...

while foraging, and the grey-bellied tesia has been recorded joining

mixed-species feeding flock A mixed-species feeding flock, also termed a mixed-species foraging flock, mixed hunting party or informally bird wave, is a flock of usually insectivorous birds of different species that join each other and move together while foraging. These ar ...

s in the non-breeding season.

Breeding

There is little information about the breeding biology of the tesias, only three species, the Grey-bellied, Chestnut-headed and Javan, have even had their nests described. They are seasonal breeders, with the Grey-bellied and russet-capped tesias nesting in May–July, and the Javan tesia having two seasons, April–June and October to December. The

nest A nest is a structure built for certain animals to hold Egg (biology), eggs or young. Although nests are most closely associated with birds, members of all classes of vertebrates and some invertebrates construct nests. They may be composed of ...

is a ball of moss for the grey-bellied tesia and plant fibres, moss and roots, and is fixed into vegetation or moss on the side of a tree, low down. The clutch size of the grey-bellied tesia is 3-5 eggs, but only 2 eggs for the Javan tesia and chestnut-headed tesia. In the chestnut-headed tesia both sexes incubate the clutch; this species is also known to occasionally be parasitized by the

lesser cuckoo The lesser cuckoo (''Cuculus poliocephalus'') is a species of cuckoo in the family Cuculidae. It is found in Bangladesh, Bhutan, China, Democratic Republic of the Congo, Hong Kong, India, Japan, Kenya, North Korea, South Korea, Laos, Malawi, Mya ...

Status

None of the tesias are considered to be

threatened A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensatio ...

by human activities, and are all listed as

least concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

by the

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

. Even the island species, which have restricted ranges, are described as common within their ranges.IUCN (2007)
IUCN Red List of Threatened Species: ''Tesia''
. Downloaded on 27 April 2008.

Species

The four species are:

References

{{Taxonbar, from=Q1187610 Bird genera Taxa named by Brian Houghton Hodgson Taxonomy articles created by Polbot