The bird species of this dictionary are those occurring in the Western and Central Palaearctic Region, as well as Northern Africa including the Sahara, and the North-East of North America, roughly within the circle on the globe above.
Avionary has always used broader limits of the Western Palaearctic region, to include Iran and the Arabian peninsula, which are now included by others as well. The southern limit of the Avionary region is now further to the South. It runs from the Atlantic Ocean from the Cape Verde Islands in the West, roughly along the 15 °N latitude line to include most of Mauritania, and the northern arid parts of Mali to North Sudan, and then includes the entire Arabian peninsula in the East. The eastern limit of the Central Palaearctic runs from the Arabian Sea east of Baluchistan and Afghanistan, where the region neighbours the Oriental (Indo-Malayan) region and then over the Hindu Kush, Tian Shen and Altai mountains and further North-East to the East Siberian Sea. Thus, the region includes almost all of Siberia, as well as the Central Asian Republics, Afghanistan and Arabia, and as a result, the whole area covered by the Ornithological Society of the Middle East (OSME). In the West, Northern and Eastern Canada, New England, as well as the entire Arctic Ocean are covered. The area covered by Avionary is expanding step by step and will eventually cover the Holarctic and African regions.
Species that only have a single or even a disputed record in the region are also included, and even a few species that have no recorded occurrence (yet) in the region, but which are taxonomically or linguistically closely related to species from the region. For many families the entire Palearctic is already covered and some selected families are extended to the Holarctic or even the whole world. Details can be found in the Species Lists.
The regions of the world where a species regularly occurs are presented indicatively under the heading “Geo”, as follows:
WPal: Western Palaearctic within the conventional limits: Europe, Northern Africa (South to about 22 °N), Middle East
rWP: Rare to more regular visitors to the Western Palaearctic
CPal: Central Palaearctic; when both WPal and EPal are covered, CPal is not mentioned
EPal: Eastern Palaearctic: Eastern Siberia, Mongolia, China except its South-East, Korea, Japan
Afr: Africa South of the Sahara (22°N)
Arab: Arabian peninsula; when the species occurs both in Afr and CPal, Arab is not added
Ori: Oriental (Indo-Malayan): from Pakistan to Indonesia and South-Eastern China
Aus: Australia and its neighbours
NAm: North America, including most of Middle America
SAm: South America
(S)AtlO: (Southern) Atlantic Ocean
(S)IndO: (Southern) Indian Ocean
(S)PacO: (Southern) Pacific Ocean
SOc: Southern Oceans, Antarctica