The Olive-tree Warbler (Hippolais olivetorum) is an 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...

 in the tree warbler

Tree warbler

Tree warblers are medium-sized warblers belonging to the genus Hippolais, formerly placed in the "Old World warbler" family Sylviidae but now separated in the marsh- and tree-warbler family Acrocephalidae. They are found in Europe, Africa and western Asia....

 genus Hippolais. It breeds in southeast 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...

 and the near east. It is 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...

, wintering in eastern and southern Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

, from Kenya

Kenya

Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...

 south to South Africa

South Africa

The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

.

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...

 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...

 is a species found in open-canopy oak

Oak

An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...

woods, olive

Olive

The olive , Olea europaea), is a species of a small tree in the family Oleaceae, native to the coastal areas of the eastern Mediterranean Basin as well as northern Iran at the south end of the Caspian Sea.Its fruit, also called the olive, is of major agricultural importance in the...

 groves, orchards and almond

Almond

The almond , is a species of tree native to the Middle East and South Asia. Almond is also the name of the edible and widely cultivated seed of this tree...

 plantations. 3-4 eggs are laid in a nest in a low tree or a bush.

This is a medium-sized warbler, similar to in size to the Barred Warbler

Barred Warbler

The Barred Warbler is a typical warbler which breeds across temperate regions of central and eastern Europe and western and central Asia. This passerine bird is strongly migratory, and winters in tropical eastern Africa....

, with a slightly longer bill and shorter tail. It is the largest Hippolais warbler, with a heavy bill, rather flat crown, long wings, and heavy legs. The adult has a dusty- or brownish-grey back and wings, and dusty-white underparts.

It feeds on invertebrate

Invertebrate

An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...

s. Its song is a succession of loud creaks and squawks, lower in pitch than other Hippolais warblers, and slower in delivery.