Environmental Biology Presentation

Wildlife Extinction

Robert I. Walls

Spring 2012

Professor

Donald Keith

History

The Irish Elk

• First documented extinction– Discovered by Thomas

Molyneux, 1697

– Extinction described by Georges Cuvier, 1812

Museum of Natural History, Washington D.C.

The Five Extinction Events

• Ordovician–Silurian• Late Devonian

• Permian–Triassic• Triassic–Jurassic• Cretaceous–Tertiary

Palais de la Découverte, Paris, photo by David Monniaux.

The Sixth Extinction Event

The Two Phases

• Human dispersal ~100,000 B.P.

• Agriculture discovered ~10,000 B.P.

The Most Susceptible

• K-selected

• Specific survival requirements

• Small population size

• Close to humans

• No conservation programs

Major Causes

• Overexploitation

• Pollution

• Invasive exotics

• Habitat Degradation

Overexploitation

Dodo Birds

• Island of Mauritius• Used as food by

Portuguese sailors• Exotic species

introduced• Extinct by 1681• Tree found to depend

on Dodo digestion of seeds for germination

Saddle-backed RodriguesGiant Tortoise

• Island of Rodrigues, Republic of Mauritius

• Hunting pressure• Last reported: 1795

In 1761, Abbé Pingré wrote: "The tortoise is not a pretty animal, but it was the most useful of those we found at Rodrigues. In the three and a half months that I spent on the island, we ate almost nothing else: tortoise soup, fried tortoise, stewed tortoise, tortoise forcemeat, tortoise eggs, tortoise liver - these were pretty much our only savouries. This meat seemed to me as good on the last day as on the first; I did not eat many of the eggs; the liver seemed to me the most delicious part of the animal. After five weeks stay I was attacked by dysentery which I kept secret, because I counted more on myself to heal it than the island's surgeon. Diet and rest put me right in a few days, but it left me with an extraordinary involuntary repugnance for this liver that I had so liked until then. Should I thus regard it as the cause of my indisposition?...Tortoise fat is very abundant and does not congeal; it is what is known as tortoise oil. This oil had no bad taste, it is very healthy, and we seasoned our salads with it, used it in frying and all our sauces. Rodrigues tortoises are a foot and a half long and bout a foot across; they were formerly large, but they are no longer given time to grow. When a bigger one is found, it is called a carrosse. These carrosses cannot harm a waken man, though they have sometimes bitten sleepers hard. The shells of these tortoises served us like baskets to carry oysters and similar provisions. The flesh of these tortoises is the colour of mutton, and approaches it for taste" (Pingré, 1763; Cheke and Hume, 2008).

Quagga

• South Africa• Aggressively Hunted• Used for meat• Skin used for grain

bags and leather

The only living quagga ever photographed - at the London Zoo in 1870, 13 years before the subspecies went extinct

Sperm Whale Harvest Records for the United States

Year # Ships Est. Whales Est. Oil Barrels1835 500 7,598 172,6831840 559 6,943 157,7911845 696 6,494 157,9171850 543 4,088 92,8921855 638 3,197 72,6491860 569 3,243 73,7081865 276 1,463 33,2421870 321 2,428 55,18318751880 173 1,656 37,6141885 133 1,065 24,203

Data from Gosho et al. 1984

Pollution

Bird Sanctuary

• DDT effects on birds first studied by Rachel Carson (late 50’s to early 60’s)

• Deaths of robins, catbirds, doves, jays, wrens, and other birds linked to pesticide exposure

Invasive Exotics

The Tasmanian “Wolf”

• Canine-like marsupial• Competed with

introduced dingo• Bounty placed by

Europeans

Habitat Degradation

Three Tiger Subspecies

• Bali• Javan• Caspian

Guam Flying Fox

• Guam, Marianas Islands, Micronesia

• Last record: 1974• Habitat degradation

and hunting believed to be causes of extinction

Gastric Brooding Frog

• Eastern Australia• Offspring incubated in

stomach• Last seen in 1985

IUCN Red List of threatened species

• 10,002 vulnerable

• 5,689 endangered

• 3,879 critically endangered

• 64 extinct in wild

• 801 extinct

Literature CitedCarson, R. 1962. Silent Spring. Houghton Mifflin. Boston, MA.

Gould, S. J. 1974. The Origin and Function of 'Bizarre' Structures: Antler Size and Skull

Size in the 'Irish Elk,' Megaloceros giganteus. Evolution 28(2):191-220.

Lowenstein, J. M. and O. A. Ryder. 1985. Immunological systematics of the extinct Quagga

(Equidae). Experimentia 41:1192-1193.

Vernon, J. E. N. 2008. Mass extinctions and ocean acidification: biological constraints on

geological dilemmas. Coral Reefs 27(3):459-472.

Gosho, M. E., D. W. Rice, and J. M. Breiwick. 1984. The sperm whale, Physeter macrocephalus. Marine Fisheries Review 46(4):54-56.

Bringing Back the Quagga. 2006. http://www.southafrica.info/about/animals/quagga.htm.

Accessed 02/23/2012.

Cylindraspis vosmaeri. 2009. http://www.petermaas.nl/extinct/speciesinfo/rodriguestortoise.

htm. Accessed 03/16/2012.

Gastric Brooding Frog. 2012 http://www.conservation.org/learn/biodiversity/species/

profiles/amphibians/Pages/Rheobatrachus_vitellinus-silus.aspx. Accessed 03/17/2012.

Guam Flying Fox - Pteropus tokudae. 2011. http://www.petermaas.nl/extinct/speciesinfo/

guamflyingfox.htm. Accessed 03/16/2012.

The Dodo Bird Extinct. http://www.bagheera.com/inthewild/ext_dodobird.htm. Accessed

03/20/2012.