How many bird species are there????? – A Quick Comparison of Checklists of World Birds

How many bird species are there???? that’s a kinda common question which keeps coming in birders’s mind….so I did a quick analysis to check out the numbers of various avian taxa across various Avian Taxonomy Checklists…

There are approximately 10,500 bird species in the world. This number varies by a few hundred birds, depending on which classification system you use. As with most animal groupings, species are being redefined and what was considered to be one species may be split into two or more species, and in other cases. two species may be combined into one species. This splits and groupings happen regularly. It has been proposed that increasing numbers of vertebrate species are largely owing to ‘taxonomic inflation’. According to this hypothesis, newly recognized species result from reinterpretations of species limits based on phylogenetic species concepts (PSCs) rather than from new discoveries.

The Avian Taxonomy Checklists which I quickly analyzed are:

Out of this 8 World Checklist of Birds three are having subspecies level taxonomy eg. IOC World Bird Names (v 3.1), Clements checklist of birds of the world and Howard and Moore complete checklist of the birds of the world.

Quick Ananlysis:

Order Family Genus Species Subspecies
IOC World Bird Names (v 3.1) 40 229 2257 10596 20988
Clements checklist of birds of the world: Version 6.6 34 228 2171 10157 19676
Howard and Moore complete checklist of the birds of the world. 3rd edition. (Updated 2006) 200 2162 9693 21737
Sibley and Monroe (1990, 1993) 146 2064 9702
BirdLife checklist of the birds of the world, with conservation status and taxonomic sources. Version 4. 198 2136 10610
IUCN Redlist 2011 25 198 2128 10052
Taxonomy in Flux Checklist 2.80 (jboyd.net) 232 2315 10526
Handbook of the Birds of the World, Lynx Edicions 28 204 2184 9867

I also did tried to find the Unique Species and Subspecies Epithet occurring in all the above checklists.

Epithet means specific names in Zoological Nomenclature, which refers to the second part (the second name) or third part within the scientific name of a species or subspecies respectively. 

eg. In Kalij Pheasant (Lophura leucomelanos), the second part leucomelanos  means Species Epithet. Whereas In Western Himalayan Subspecies of Kalij Pheasant (Lophura leucomelanos hamiltoni) , the second part leucomelanos  means Species Epithet and third part hamiltoni is Subspecies Epithet.

Unique Epithet – Species Unique Epithet – Subspecies
IOC World Bird Names (v 3.1) 5917 10228
Clements checklist of birds of the world: Version 6.6 5685 9765
Howard and Moore complete checklist of the birds of the world. 3rd edition. (Updated 2006) 5478 10389
Sibley and Monroe (1990, 1993) 5453
BirdLife checklist of the birds of the world, with conservation status and taxonomic sources. Version 4.  5928
IUCN Redlist 2011 5670
Taxonomy in Flux Checklist 2.80 (jboyd.net) 5884
Handbook of the Birds of the World, Lynx Edicions 5562

Here are the list of Top 5 occurrences of Species and Subspecies Epithets.

Top 5 Unique Epithet – Species Top 5 Unique Epithet – Subspecies
Clements checklist of birds of the world: Version 6.6
Epithet Occurance Epithet Occurance
minor 26 minor 75
affinis 25 affinis 66
gularis 25 occidentalis 51
viridis 25 orientalis 50
superciliaris 23 intermedius 43
IOC World Bird Names (v 3.1)
minor 26 minor 77
affinis 26 affinis 64
viridis 25 occidentalis 60
capensis 24 orientalis 52
gularis 24 australis 46
Howard and Moore complete checklist of the birds of the world. 3rd edition. (Updated 2006)
minor 25 minor 80
viridis 24 affinis 67
gularis 23 occidentalis 59
capensis 23 orientalis 53
superciliaris 22 intermedius 47
Taxonomy in Flux Checklist 2.80 (jboyd.net)
affinis 26
minor 26
viridis 25
gularis 24
capensis 24
Handbook of the Birds of the World, Lynx Edicions
minor 25
viridis 25
affinis 24
gularis 23
capensis 22
Sibley and Monroe (1990, 1993)
minor 25
gularis 24
affinis 24
viridis 24
capensis 23
BirdLife checklist of the birds of the world, with conservation status and taxonomic sources. Version 4. 
minor 25
affinis 25
viridis 25
gularis 24
capensis 23
IUCN Redlist 2011
affinis 25
minor 25
viridis 25
gularis 24
capensis 23

Here is the quick rundown to Birdlife Checklist of the birds of the world with conservation status.

EXTINCT (EX) 132
EXTINCT IN THE WILD (EW) 4
CRITICALLY ENDANGERED (CR) 189
ENDANGERED (EN) 381
NEAR THREATENED (NT) 843
VULNERABLE (VU) 683
DATA DEFICIENT (DD) 62
NOT RECOGNISED (NR) 1036
UNCER REVIEW (UR) 81
LEAST CONCERN (LC) 7759

I’m currently analyzing Indian Birds Checklist in similar fashion…so keep watching this space for the updates……