Radde's Warbler, Phylloscopus schwarzi, is a leaf warbler

Leaf warbler

Leaf-warblers are small insectivorous birds belonging mainly to the genus Phylloscopus. They were formerly included in the Old World warbler family but are now considered to belong to the Phylloscopidae, a family created in 2006. The genus is closely related to Seicercus and some species have been...

 which breeds in Siberia

Siberia

Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...

. This warbler is strongly migratory

Bird migration

Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

 and winters in southeast Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

.

This is a bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

 of open woodlands with some undergrowth near water. The nest is built low in a bush, and eggs are laid. Like most Old World warbler

Old World warbler

The "Old World Warblers" is the name used to describe 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 cisticolas into...

s, this small passerine

Passerine

A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...

 is insectivorous.

This small warbler is prone to vagrancy as far as western Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 in October, despite a 3000 km distance from its breeding grounds. It has been recorded from the Copeland Bird Observatory

Copeland Islands

The Copeland Islands is a group of three islands in the north Irish Sea, north of Donaghadee, County Down, Northern Ireland consisting of Lighthouse, Mew and Copeland Island.-Area of Special Scientific Interest :...

 in County Down

County Down

-Cities:*Belfast *Newry -Large towns:*Dundonald*Newtownards*Bangor-Medium towns:...

, Northern Ireland

Northern Ireland

Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...

 where it was first recorded for Northern Ireland in 2008.

This is a warbler similar in size to a Willow Warbler

Willow Warbler

The Willow Warbler is a very common and widespread leaf warbler which breeds throughout northern and temperate Europe and Asia, from Ireland east to the Anadyr River basin in eastern Siberia...

. The adult has an unstreaked brown back and buff underparts. There is a very long prominent whitish supercilium, and the pointed bill is thicker than that of the similar Dusky Warbler

Dusky Warbler

The Dusky Warbler, Phylloscopus fuscatus, is a leaf warbler which breeds in east Asia. This warbler is strongly migratory and winters in southeast Asia. It has a foothold in North America in Alaska, and has also occurred in California...

. The legs are paler than Dusky's, and the feet look large, reflecting the more terrestrial lifestyle of this warbler. The sexes are identical, as with most warblers, but young birds are yellower below. The call is a soft chick.

The binomial commemorates the German astronomer Ludwig Schwarz (1822-1894).