Alström's warbler (''Phylloscopus soror''), or the plain-tailed warbler, is a species of

Old World warbler Old World warblers are a large group of birds formerly grouped together in the bird family Sylviidae. The family held over 400 species in over 70 genera, and were the source of much taxonomic confusion. Two families were split out initially, the ci ...

in the family

Phylloscopidae Leaf warblers are small insectivorous passerine birds belonging to the genus ''Phylloscopus''. Leaf warblers were formerly included in the Old World warbler family but are now considered to belong to the family Phylloscopidae, introduced in 20 ...

. It was first described in 1999. It breeds only in

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

and winters as far as

Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...

Laos Laos (, ''Lāo'' )), officially the Lao People's Democratic Republic ( Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ, French: République démocratique populaire lao), is a socialist ...

Cambodia Cambodia (; also Kampuchea ; km, កម្ពុជា, UNGEGN: ), officially the Kingdom of Cambodia, is a country located in the southern portion of the Indochinese Peninsula in Southeast Asia, spanning an area of , bordered by Thailand t ...

and

Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...

. Its natural

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

is temperate

forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...

Habitat and migration

Alström's warbler often

forages Foraging is searching for wild food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce. Foraging theory is a branch of behavioral ecology that studies the foraging behavi ...

in a low, dense growth of forests. This bird is known to eat insects and catch prey during short flights. The bird is not currently globally threatened. This bird has a very large range and does not approach the potential of being a

vulnerable species A vulnerable species is a species which has been Conservation status, categorized by the International Union for Conservation of Nature as being threatened species, threatened with extinction unless the circumstances that are threatened species, ...

. The warbler typically breeds in warmer,

temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

areas. These areas are found within evergreen broadleaf forest zones and lush

undergrowth Undergrowth usually refers to the vegetation in the lower part of a forest, which can obstruct passage through the forest. The height of undergrowth is usually considered to be 0.3 – 3 m (1 – 9 ft.). Undergrowth can also refer to all ...

in mature forests. It has a scattered breeding range across central and eastern China. The warbler tends to breed in bushes and small trees of low to moderate height, in recently cleared areas. This bird is a migratory species. It migrates during the winter to southern Myanmar, Thailand, Cambodia, southern Vietnam, and southern China.

Genus

Alström's warbler was previously placed in the genus ''Seicercus''. 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 2018 found that neither '' Phylloscopus'' nor ''Seicercus'' were

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

. In the subsequent reorganization the two genera were merged into ''Phylloscopus'' which has priority under the rules of the

International Commission on Zoological Nomenclature The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries. Orga ...

. The

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

honours the Swedish ornithologist

Per Alström ''Per'' Johan Alström (born 9 April 1961) is a Swedish Professor of ornithology. He researches in taxonomy, systematics, and evolution, with birds in Asia as a specialty. Alström works at the Department of Ecology and Genetics (Animal Ecology) a ...

Appearance and identification

Alström's warbler measures 11-12 cm in size. The female is on average smaller than the male. The Alström's warbler can be commonly mistaken for Martens's, Gray-crowned, White-speckled, and Bianchi's

warblers Various Passeriformes (perching birds) are commonly referred to as warblers. They are not necessarily closely related to one another, but share some characteristics, such as being fairly small, vocal, and insectivorous. Sylvioid warblers Th ...

. The bird has a greyish-black color that fades on the forehead as well as a mix of green that surrounds the eyes. The underside of the bird is a vibrant yellowish-green color whereas the wings and back have a grey crown with black stripes. This bird has a distinct yellow

eye-ring The eye-ring of a bird is a ring of tiny feathers that surrounds the orbital ring, a ring of bare skin immediately surrounding a bird's eye. The eye-ring is often decorative, and its colour may contrast with adjoining plumage. The ring of feather ...

that may diffuse above the eye. To distinguish this bird from others, the Alström's warbler is larger billed, smaller tailed, and has a more distinct white lining in the outer tail feathers than Martens's and Gray-crowned warblers.

Breeding

Based on male singing activity, the mating activity of the warbler is from May to June. The non-breeding distribution and migratory periods are not fully known at this time. This bird has been located in southern China outside of its breeding range from early September to early October. The warbler has been seen in Thailand during mid-September, as well as in southern Vietnam in late September. The non-breeding warbler has been observed in southern Myanmar up until mid-April. The warbler has been spotted on Chinese breeding grounds in late April. Its distribution in the non-breeding season is hard to estimate because there is an overlap of non-singing similar species which makes identification very difficult.

Birdsong

This bird has a very simple song, which consists of short, quick

strophes A strophe () is a poetic term originally referring to the first part of the ode in Ancient Greek tragedy, followed by the antistrophe and epode. The term has been extended to also mean a structural division of a poem containing stanzas of varying ...

, typically with a short ''chip'' as an introductory note. The introductory note is followed by 2-5 short, whistled notes. The whistled notes are arranged into an element group that is usually given 2-4 times, followed by a pause. The warbler has a distinctly higher-pitched and broader

frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...

span than the ''P. valentini''. The song can be easily simplified by a brief ''che-witchy-chew-witchy-chew''.

References

Alström's warbler Birds of China Alström's warbler Alström's warbler Alström's warbler Taxonomy articles created by Polbot {{Phylloscopidae-stub