Insular Fauna

Insular fauna is the fauna situated on an island. There are different types of islands and they are different from each other because of their age and there way of emergence. There are Continental Islands, Oceanic islands and ancient islands.

1. Insular Fauna

2. Insular Fauna : Insular means “ situated on an island ” and fauna means “ animals”.  The study of animal life on islands forms one of the fascinating chapters in the study of Zoogeography  The biological environment on the island is different from that of the continents and this has a far reaching effect on its fauna. In 1859, Darwin suggested that islands are generally classified into two distinct categories named as:

3. 1 . Continental Islands 2.Oceanic Islands The term ancient island is reserved for such islands which were separated from main land million of years ago. These means that they are oceanic islands but separated for a very long period. CONTINENTAL ISLAND : Islands that have been connected with the nearby mainland at one time or other  Through the sinking of the land or by a rise in the sea level they must have become separated from the continent by a stretch of the sea

4. The sea, separating the two may be narrow like the straits of Dover which separates the continental islands of Great Britain form the continent of Eurasia or may be wide like the Formosa strait which separates the island of Formosa from mainland China  Are close to the mainland and they resemble each other geologically  Great Britain is a young continental island  Borneo, Formosa and Japan are older

5. Strait of Dover

6. The fauna of the continental island as well as the mainland are more or less identical and always include certain proportion of mammals and amphibia.  The terrestrial fauna of the continental island must have reached the island across the dry land when the island was still connected with the continent.  The difference that one notices in the faunal content of the island and the mainland depends upon the length of time a continental island has been independent form the mainland.  If the island is an old one it will be lacking in animals which are comparatively new comers to mainland and secondly the animals in the island would have undergone extensive adaptive radiation resulting in the production of a wide variety of species unknown in the mainland.

7. Some of the peculiar life forms present in the continent islands are mainly due to the evolution of the new forms under changed insular conditions  Sometimes continental islands have preserved some of the species which have become extinct on the mainland  The survival of such forms on the continental islands is due to lack of competition from the more progressive forms and hence they are shielded from the hazardous effects of natural selection  The following are the important continental islands:  1. Great Britain, 2. Java, 3. Philippines, 4 Formosa and 5. Japan

8. BRITISH Isles: Consist of 2 main islands off the coast of Europe, namely 1. Great Britain, about 89,000 sq. miles 2. Ireland, about 32,900 sq. miles in area. CLIMATE : It’s cold temperate type and islands have low mountains and low lands. FAUNA: Modern fauna is very poor when compared with Europe. The paucity of mammalian and reptilian fauna has been due to successive glaciation to which the islands seem to have been subjected. The whole of British fauna of Pliocene was wiped out during Pliestocene glaciation and modern fauna has been gained since then.

9. fresh water fish Newts, toads, frog Red grouse Hedgehogs, moles, Shrews, rabbits

10. Fishes: 1 6 species of fresh water fish in Britain and only 8 of these are in Ireland. Amphibian : 3 species of Newts, 2 sp. Of toads and 1 of frog. And Ireland has only one species of Newts. Reptiles: Britain has 3 species of lizards, 3 species of snakes( Grass, Smooth and Viper) but of these 6 species of retiles only one species of lizards is found in Ireland and even snakes are not found in Ireland. Both islands lacks Turtles . Birds: Too many species of birds is in both islands and one is endemic which is Red grouse, Lagopus acoticus . Mammals : Ireland mammalian fauna is insignificant while, in Britain Hedgehogs, moles, Shrews, rabbits, squirrels, foxes, cats and bats.

11. JAPAN The Japanese archipelago (extensive group of islands) is a chain of more than 1,000 islands paralleling east coast of Asia. The largest island HOUSHU is about 87,000 sq. miles, KYUSHU 16,000 sq. miles and SHIKOKU 7,000 sq. miles in area. These islands are the main part of what is called Japan. CLIMATE: Warm temperate type and is ecologically diverse with lowlands and high mountains. FAUNA : Fish: 45 sp. Of fresh water fish . Amphibians : 3 Families of salamander and 10 sp. Of frogs and toads. Reptiles : 2 sp. Of Turtles, few lizards and several sp. Of snakes. Birds: Numerous. Mammals : 6 genera of insectivores, one monkey one wild boar, one deer, 3 rabbits, 10 rats, 11 bats, 2 bears and 6 mustelids. The main island of Japan is about size of Britain but Japan is warmer and had not been subjected to glaciation and it’s fauna is more diverse .

12. Sea of Japan North Pacific Ocean 45 sp. of Fish salamander toads. frogs Birds Turtles lizards snakes . insectivores monkey wild boar deer 11 bats Insectivores, Monkey, wild boar, Deer, bats,

13. FORMOSA It’s Chinese name is TAIWAN. It lies about 9 miles away from china. Size is 14,000 sq. miles and ecologically diverse and rich with huge mountains. Fauna: The vertebrate fauna is moderately rich. Fish : 54 sp. Of fresh water fish . Birds: Avian fauna rich and bears striking resemblance to South india , Malaya and Japan. Mammals : 5 genera of insectivores, 1 mole, 11 carnivores, 1 bear, 1 leopard, 1 anteater, 5 ungulates, 1 pig, 3 deer, 1 rabbit and several rats are included.

14. fresh water fish Birds Bats, Leopard ,,, bats, ungulates , moles

15. SRI LANKA Sri Lanka (Ceylon) lies southeast of the tip of India and is about 25,000 sq. miles in area. Climate: Tropical island with some Mountains. Fauna: It’s fauna is moderately rich in all main classes of vertebrates but fish and mammals are most significant . Fish: Ceylon has variety of fresh water fish . Mammals : Has 83 mammalian species. Many of the mammals are same as those of south India. However, Sri Lanka lacks some significant mammal groups. Among large mammals, sri lanka lacks Wolves, Wild dogs, but has a Jackal , lacks tiger but has a leopard----- lacks rhinoceros but has the Elephant----lacks all types of bovids of India except buffaloes . Although most of the vertebrates of Sri Lanka are Indian, few lizards, snakes and birds have their closest relatives in Indochinese or Malayan region.

16. fresh water fish . Jackal Elephant buffaloes

17. OCEANIC ISLANDS Oceanic islands are those which never had a connection with the main continent. Features: They are generally the islands of volcanic origin or may be formed by the building up of coral reef or by the combination of both. Strong winds prevail on these islands forcing insects to become wingless. Flora and fauna is different from the nearest mainland, although some of it may have been derived from there. Freshwater fishes, amphibians and mammals are rare or absent. Most likely mammals on these islands are bats, rats and insectivores.

18. It has certain features that are common with other mainland. Vegetation and fauna tend to be sparse. Mammals , Amphibians and freshwater fishes are totally absent except few bats and rats. The absence of carnivores on oceanic islands leads to certain general trends in the evolution of other island inhabitants. For example: Birds also have a tendency to become flightless as in the case of Dodo in Mauritius. Lizards and turtles have a tendency to become giants as on the Galapagos Islands.

19. Dodo in Mauritius

20. SOME Selected OCEANIC ISLANDS ARE FOLLOWING: St. Helena, Galapagos, Easter Islands, Fiji, Azores, Bermuda, Mauritius

21. GALAPAGOS ISLANDS: Lie in pacific ocean and composed of 5 large and 10 smaller islands. Covers the area of 2,870 sq. miles. Geologically they all are volcanic and separated from other mainlands by deep waters. Coastal areas are dry and bare. Inland areas are covered with humid forest. Fauna 2 species of mammals Many land birds Many reptiles No amphibians and freshwater fishes. It has 100 species of birds, in which 72 species are unique. It has a penguin specie that live in tropics Unique flightless comorants . Has famous birds ‘’Darwin finches’’

22. amphibians and freshwater fishes. birds penguin comorants . ’Darwin finches

23. Two species of giant iguana lizards occur of which one is cactus feeding on land And the other dives in the sea to feed on sea-weed. Tortoises are giant, their shell about a meter in diameter. There are two species of snakes and two species of geckos. Few bird species exist and resemble South American birds. . Flightless comorants

24. KRAKATAU It is a group of 3 islands which lie in sundra straits between Sumatra and java. Early accounts describes that it was consisted of one large and 2 small islands, but on 17 august 1883 the large island blew up, leaving a small piece of original island above water and the other part completely covered in hot volcanic ash. Since then these islands are continues to sink and rising. So it continually changes its profile. Fauna Due to eruption its fauna and flora were completely destroyed. Within 2 years 11 ferns 8 flowers 8 plants are recorded

25. According to 1908 survey It has 13 species of birds 2 species of lizards 192 species of insects which includes ants , flies, beetles, dragon flies, spiders etc. According to 1921 survey It has 3 times more species of animals as compared to the survey of 1908. Birds has increase to 29 species. 2 species of earthworms were also present. Insects were increase to 500 species. 7 species of arthropods were also recorded.

26. ferns flowers birds lizards insects earthworm

27. St. helena Volcanic island Area is 80 square miles Fauna is poor and sparse. There are no native mammals, reptiles, amphibians and fishes. 203 species of beetles 29 species of land snails African plover is the only resident bird. Land molluscs include snails, which perhaps have reached here through their eggs carried stuck on the legs of migratory birds. Plants resemble those of South America, whose seeds must have also been carried by birds.

28. African plover

29. beetles land snails African plover Land molluscs

30. ANCIENT ISLANDS There are two good examples of ancient islands : Newzealand Madagascar   1-Newzealand: Geography:- Newzealand lies about 1000 miles south east off Australia. It is composed of two main islands covering up an area of 0.1 million sqaure miles. It is characterized by :- Mountain Open country Wide variety of temperate vegetation The islands are geologically compkex and composed of extinct volcanoes as well as sedimentary rocks .

31. bats KIWIS". old parrots lizards Sp henodon punctatus frog

32. Fauna: Fauna is characterized by absence of many animals and for presence of certain of relics or remains of old vertebrate stocks as well as by presence of flightless birds. Mammals: No native mammals except 2 families of bats. Birds: Flightless birds:- 3 unique species of flightless birds known as "KIWIS". Flightless rails and kakapo (old parrots) are present . Extinct ones: A number of flightless birds have already been extinct. There were about 20 species of Moas, some were as large as ostriches and they livrd in Newzealand from Miocene till recent times and are now extinct. Flight birds:- Some belong to worldwide familes . Some are Australian. There are 2 endemic families-

33. Wrens Wattlebirds A remarkable bird is Kea, genus of large parrot, which sits on back of sheep and tears holes in flesh to eat the kisney fat. Reptiles: Common lizards are present Snake and turtles are absent except marine ones. A unique and striking relic of past i.e. Sp henodon punctatus is present. It is last surviving member of reptilian order Rhyncocephalia , which became extinct 100 million years ago . Amphibians: Only one unique specie of frog Liopelma is present. Fish: No strictly freshwater fishes.   It appears that vertebrate fauna is very ancient one and fauna i highly endemic. These facts give rise to questions like 1-Where did this fauna originate? 2-How did it get into Newzealand ? 3-How long Newzealand has been an island?

34. Assumptions: Newzealand could have had a land connection with Australia in Mesozoic era. A narrow strip of shallow sea runs from North West corner of Newzealand to Northeast corner of Australia, a distance of some 100 miles and this may indicate the site of Mesozoic land bridge. The archaic animals of Newzealand might have migrated there at times of existance of land bridge. But once the connection was lost, sometimes in Jurassic period. It prevented further influx of other amphibians, reptiles and mammals. The later part of its vertebrate fauna has been acquired like that of an oceanic island from across the sea.  

35. 2-Madagascar: Geography: Madagascar is a large island in Indian ocean, about 1000 miles long with an average width of 260 mile. Its greatest breadth being 360 miles. It is an old island with scattered volcanic peaks in the centre. It is characterized by presence of dense forests bamboo jungles Tropical swamps bare rock country sand dunes The cannel between Africa and this island is called Mozambique Channel and is 100 km wide and 1000 meters deep .

36. insectivores . rat River hog Mongoose bats fruit eater) giant elephant bird rail like birds Tree frogs freshwater turtles chameolons snakes

37. Fauna: Fauna of this region is one of the most interesting in whole world. -86 families of terrestrial vertebrates are found in this area: 12 mammals 55 birds 15 reptiles 4 amphibia 8 families are totally confined to this area. Mammals: The most characteristic family of mammals is Lemuridae . Within this family, are grouped 'true lemurs' which are not found elsewhere. -->Insectivores: 3 families are present , of insectivores.

38. One is highly peculiar and unique to this region, known as Tenrecidae . This family is unknown elsewhere and represented by 30 species.   --> Carnivores: They are represented only by Civets Mongoose --> Rodents: They are represented by a family of rat only. --> Ungulates: They have only one representative that is River hog, Potamochasus . --> Bats: Many bats are present with African and Oriental affinities

39. Birds: Bird fauna is peculiar. Madaascar bird fauna is less rich than African one and many peculiar families are absent, like; Touracos Ostriches Hornbills Woodpecker Plaintain eaters Secretary birds Total 51 families are present. 4 families are endemic that are as follows:- Phillepittidae (fruit eater) Leptosomatidae (giant elephant bird) Mesoenatidae (rail like birds) Vaugidae (insect and chaeolon eaters)

40. Reptiles: This island is free from poisonous snakes, python, varanus , agamid lizards and turtles. There is a good representation of freshwater turtles, chameolons , skinks and snakes(typhons, boas and colubrid etc.) Amphibians: Tree frogs are present Common toads, pipid frogs and caecilians are absent . Affinity The great island is characterised by immense number of unique lemurs and tenrecs and absence of monkeys, ungulates, lions, tigers, hyenas and otters etc. The birds fauna is so much different from African one.

41. It shows affinity with America in presence of - Podocnemius (a turtle) -Iguanidae (lizard family) Its relationship with India is much marked. Some half a dozen of birds found in this region belong to Orientak region and are not represented in Africa. Assumptions: These pecularities entitle Madagascar to rank as an independent zoogeographical region. The term ancient island is supported by composition of its fauna. Presence of many endemic families and archaic animals indicate a fairly long isolation from mainland. Madagascar may be infact an ancient continental island which might have had land connections with Africa or India or both.

42. It is generally believed that Madagascar have had a land connection with Africa during Mesozoic period. This would have enebled African amphibians, reptiles, birds and mammals to enter into Madagascar by land. Other mammaks such as insectivores, lemurs, sudenecked turtles are said to have crossed during Cretaceous or Eocene period. There is no evidence to this theory. It is not easy to say the status of Madagascar whether it is an continental island or oceanic island. Perhaps, its recognition as "ancient island" is more appropriate.          

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