Species Examples


While many extinctions in historical times have been directly observed or inferred (e.g., Tasmanian "wolf," passenger pigeon, Carolina parakeet, ivory-billed woodpecker, great auk, dodo, Steller's sea cow, Caribbean monk seal, etc.), future extinctions are usually predicted by combining empirical and theoretical relationships between land area size and species numbers.

This prediction process is difficult since it involves estimating two unknowns: the number of species found only in particular areas and the rate at which those natural areas will become unsuitable for these organisms with increasing resource use by humans.

Given that biologists can only roughly estimate the total number of species, obtaining the more detailed information required to calculate precise "rates" is a major challenge.

Whatever the actual value might be, however, there is substantial agreement that current extinction rates are comparable and perhaps even greater than the five geologic mass extinctions.

Moreover, if biologists are anywhere close in their estimates of future species losses (e.g., 5 to 50% lost in 30 years), the present mass extinction is the fastest, being on the order of 100 to 10,000 times greater than background rates of extinction.

Whereas all previous mass extinctions were driven by geological and astronomical processes and took millions of years to take their tolls on species diversity, the current one is measurable over mere decades (see the gallery of images below).

Furthermore, this mass extinction is the first one caused, directly and indirectly, by a single species - humans.

Passenger pigeon (Ectopistes migratorius), extinct. Drawing by: Mark Catesby

Carolina parakeet (Conuropsis carolinesis), extinct. Drawing by: Mark Catesby	Round Island Boa (Bolyeria Multocarinata), extinct. Artist unknown

Martinique Lizard (Leiocephalus herminieri), extinct. Drawing by: John Gabriel Pretre

Quagga (Equus Quagga), extinct. Drawing by: William Cornwallis Harris

Large Copper (Lycaena Dispar Dispar), extinct. Drawing by: John Obadiah Westwood	Round Combshell (Epioblasma Personata), extinct. Drawing by: George Brettingham Sowerby

Japanese Wolf (Canis Lupus Hodophilax), extinct. Artist Unknown

Losses of Species and Habitats menu