The Western Palaearctic or Western Palearctic is part of the

Palaearctic realm The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...

, one of the eight

biogeographic realm A biogeographic realm or ecozone is the broadest biogeographic division of Earth's land surface, based on distributional patterns of terrestrial organisms. They are subdivided into bioregions, which are further subdivided into ecoregions. De ...

s dividing the Earth's surface. Because of its size, the Palaearctic is often divided for convenience into two, with Europe, North Africa, northern and central parts of the

Arabian Peninsula The Arabian Peninsula, (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَبِيَّة, , "Arabian Peninsula" or , , "Island of the Arabs") or Arabia, is a peninsula of Western Asia, situated northeast of Africa on the Arabian Plate ...

, and part of temperate Asia, roughly to the

Ural Mountains The Ural Mountains ( ; rus, Ура́льские го́ры, r=Uralskiye gory, p=ʊˈralʲskʲɪjə ˈɡorɨ; ba, Урал тауҙары) or simply the Urals, are a mountain range that runs approximately from north to south through western ...

forming the western zone, and the rest of temperate Asia becoming the Eastern Palaearctic. Its exact boundaries differ depending on the authority in question, but the '' Handbook of the Birds of Europe, the Middle East, and North Africa: The Birds of the Western Palearctic'' (''BWP'') definition is widely used, and is followed by the most popular Western Palearctic checklist, that of the Association of European Rarities Committees (AERC). The Western Palearctic realm includes mostly

boreal Boreal may refer to: Climatology and geography *Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch *Boreal climate, a climate characterized by long winters and short, cool to mild ...

and

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 ...

climate ecoregions. The Palaearctic region has been recognised as a natural zoogeographic region since Sclater proposed it in 1858. The oceans to the north and west, and the

Sahara , photo = Sahara real color.jpg , photo_caption = The Sahara taken by Apollo 17 astronauts, 1972 , map = , map_image = , location = , country = , country1 = , ...

to the south are obvious natural boundaries with other realms, but the eastern boundary is more arbitrary, since it merges into another part of the same realm, and the mountain ranges used as markers are less effective

biogeographic Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...

separators. The climate differences across the Western Palearctic region can cause behavioral differences within the same species across geographical distance, such as in the sociality of behavior for bees of the species ''

Lasioglossum malachurum ''Lasioglossum malachurum'', the sharp-collared furrow bee, is a small European halictid bee. This species is obligately eusocial, with queens and workers, though the differences between the castes are not nearly as extreme as in honey bees. Ea ...

''.

References

{{reflist Palearctic realm Biogeography Phytogeography Natural history of Europe