<Tr> <Td_colspan="2"> <P> Geospiza Camarhynchus / Platyspiza Certhidea Pinaroloxias </P> </Td> </Tr> <P> Geospiza Camarhynchus / Platyspiza Certhidea Pinaroloxias </P> <P> Darwin's finches (also known as the Galápagos finches) are a group of about fifteen species of passerine birds . They are well known for their remarkable diversity in beak form and function . They are often classified as the subfamily Geospizinae or tribe Geospizini . They belong to the tanager family and are not closely related to the true finches . The closest known relative of the Galápagos finches is Tiaris obscurus . They were first collected by Charles Darwin on the Galápagos Islands during the second voyage of the Beagle . Apart from the Cocos finch, which is from Cocos Island, the others are found only on the Galápagos Islands . </P> <P> The term "Darwin's finches" was first applied by Percy Lowe in 1936, and popularised in 1947 by David Lack in his book Darwin's Finches . David Lack based his analysis on the large collection of museum specimens collected by the 1905--06 Galápagos expedition of the California Academy of Sciences, to whom Lack dedicated his 1947 book . The birds vary in size from 10 to 20 cm and weigh between 8 and 38 grams . The smallest are the warbler - finches and the largest is the vegetarian finch . The most important differences between species are in the size and shape of their beaks, which are highly adapted to different food sources . The birds are all dull - coloured . </P>

How many types of finch species are there