The previously mentioned maps and data demonstrated that wildlife adapt to specific areas and that many species are only found in certain habitats.  Many habitats are being destroyed.  Barely 1% of the original tall-grass prairie remains in the U.S.; it once covered 400,000 square miles.  About half of the short-grass prairie habitat remains in the U.S.; it once covered over 600,000 square miles.  Only 2-5% of the old growth forests remain in the U.S. (since 1970, 1 billion acres have been cut).  The amount of forested land in the United States has decreased by about one quarter since 1700.

     Between 1960 and 1990, 20% of all the earth’s rainforests were cut.  During this time period, Asia lost 1/3 of its forests.  Since 1980, 80% of the Amazon rainforest has been cut and 100 square kilometers of Amazon rainforest is cut each year,  About fifty acres of rainforest are cut each minute globally.

     Islands frequently carry species that occur nowhere else in the world.  For example, of the 135 birds that occurred only in Hawaii, 101 are already extinct, 24 more are in danger.  The majority of the 161 birds which have become extinct have been island species.

     About 140,000 square kilometers of tropical rainforest are cut/year.  During the 1990s, the earth’s forest cover decreased by 4% and about half of the world’s forests have been lost since the dawn of agriculture.  More than half the earth’s wild wetlands have been lost during the past century.

     Due to population growth alone, the percentage of species in an average nation is expected to rise to about 7% by the year 2020 and 14% by 2050.  Human population growth is a primary factor in an estimated 88% of the species whose condition is considered threatened (McKee, 2003).



Extinction is a natural process; it is estimated that over 99.9% of all the living things that have ever existed in earth's history are now extinct.  Sometimes extinction occurs at a slow rate; there are other times known as mass extinctions.

Due to the human impact on the natural world, it is estimated that at least 100 species become extinct every day; at this rate, the mass extinction through which we are now living will soon (by the year 2000?) surpass the Cretaceous extinction and become the 2nd largest in earth's history.

Why aren’t you aware of the species which become extinct every day?

1)     They are Rare:

--Look at the list of endangered species in New York State and those species which only exist in a few states.  How many of those have you heard of?

2)     Most people are unfamiliar with many groups of organisms, such as insects, freshwater mollusks, etc.  Ninety-five percent of all animal species are invertebrates and therefore many species could go extinct from your area without your being aware of them ever existing.

3)     Since most of the species on earth do not even occur in the U.S., most of the extinctions are not occuring in the U.S.  Two thirds of earth’s plant and animal species live in the tropics; many of which have yet to be discovered.  Island species are particularly vulnerable to extinction.



1)     Some currently endangered species are very close to extinction because their numbers are so small (all of the following population estimates are from the mid-1990s):

--Schaus Swallowtail Butterfly: under 100

--Florida Panther: 30-50

--Black Footed Ferret: 450

--Cooke’s Kokio: a Hawaiian tree that no longer occurs in the wild, fewer than 50 grafts still survive that have yet to produce seeds

--Flat Spired Three Toothed Land Snail: fewer than 180

--Flat Pocketbook Pearly Mussel: 9 small colonies

--Laysan Duck: 500

--Swamp Pink: 120 known sites

--Wyoming Toad: 50

--Northeastern Beach Tiger Beetle: 45 groups

--Red Wolf: fewer than 300

--Macfarlanes Four-O’Clock: 10 patches

--Plymouth Redbelly Turtle: 300

--Green Pitcher Plant: 26 known sites

--Hellers Blazing Star: 7 groups (most fewer than 50 plants)

--Arizona Agave: 60 clones

--Florida Key Deer: 200-400

--Na’u: 15 bushes

--Santa Cruz salamander: 9 colonies

--Chisos Mountain Hedgehog Cactus: under 200

--Kauai Hau Kuahiwi: 100 (a flowering tree)

--Whooping Crane: 175

--Key Tree Cactus: under 200

--Boulder Darter (a small perch): 8 small groups

--Dwarf Wedge Mussel: 19 groups (some in New York)

--Tenessee Purple Coneflower: 5 patches

--Running Buffalo Clover: 24 colonies


2)     Many U.S. species have already become extinct

     There are a number of organisms on the Endangered Species List that have not been seen in years/decades and may already be extinct such as the turgid blossom, yellow blossom, little Mariana fruit bat, Mariana mallard, scioto madtom.  The Bachman’s warbler and Ivory billed woodpecker are extinct from the U.S. but small populations still survive in Cuba. 

     Some species that inhabited New York in the past several hundred years have become completely extinct: these include Passenger Pigeon, Eastern Bison, sea mink, heath hen, Townsends Finch, and the Eastern Wapiti (a deer).  Other species have become extinct from other parts of the U.S. including the badlands bighorn sheep, Oregon bison, Carolina parakeet, Florida wolf, and long-eared kit fox. The extinct pasenger pigeon was once considered one of the most common birds whose migrating flocks could darken the sky for hours. In 1810, a flock of passenger pigeons in Kentucky were estimated as having 2.2 billion individuals and another in 1871 as having 136 million individuals.



a)  Conservationist reasoning: They are useful to humans.

1) Plants (especially in rainforests) and phytoplankton supply most of the world's oxygen and remove large amounts of carbon dioxide from the air.   The climate will be altered without them.

2) Although seemingly insignificant, many small species are at the bottom of food chains and their loss impacts larger species.

3) The food supply: Most of the earth's crops come from 130 different plants; most of these originated from 12 regions of the world where the wild ancestors are still found.   Geneticists often look to these wild species once new strains of pests blight crops.  When blights hit Columbian or Brazilian coffee strains, new wild strains from the Ethiopian highlands were found.  In the late 1970s, grassy stunt virus hit the rice crop of southern and eastern Asia.  After searching 47,000 varieties for a resistant strain, a wild plant was found in an Indian valley that has since been flooded by a hydroelectric dam.

    After searching all 6,500 varieties of barley, the California Agricultural Lands Project found an Ethiopian strain resistant to the yellow dwarf virus that now protects all of California's $160 million barley crop.  The U.S. saves $50 million annually dus to disease resistant wheat genes which came from a seemingly worthless wheat strain from Turkey.  In 1981, British beer industry gained $15 million after incorporating a wild hop plant.  Our crops are bred to decrease genetic diversity; of the vegetable varieties that existed in 1900, only 3% exist today in the U.S.; this leaves crops in danger from new parasites.

4)  Drugs: About 1/4 all U.S. prescriptions are products extracted from plants, 13% from microorganisms, and 3% from animals.  Chemicals from palnts are the source of 80% of the top 150 prescription drugs.  Aspirin was originally isolated from the flower meadowsweet, armadillos are being used in experiments for cures against leprosy because they are the only other organism that can contract the disease.  More than $180 million/year is gained from 2 drugs produced from the small rosy periwinkle (a flower from Madagascar) that cure Hodgkin's disease (affects 5-6,000 Americans annually) and lymphocytic leukemia.  

     Other examples of drugs from plants include: bromelain (controls inflammation), codeine (analgesic), colchicine (anticancer), digitoxin (cardiac stimulant), diosgenin (source of female contraceptive), L-dopa (suppresses Parkinson's disease), ergonovine (migraines & hemorrhaging), glaziovine (antidepressant), indicine N-oxide (anticancer), menthol, morphine, quinine (antimalarial), reserpine (reduces high blood pressure), and scopolamine (sedative).

5) Defense from pests: The weed plants and insect pests which threaten food production and the insects which can spread disease have wild predators.  For example, certain wasps stop borers from destroying sugar cane crops.

6) Ecotourism:  The United Nations that about $230 billion/year in ecotourism.  Many wild areas and animal species can generate far more income for a country through tourism than through their destruction.

b) preservationist reasoning: Every species has a right to exist and the all species contribute to the beauty of the world.  Which of the species depicted in the images below could the world do without?  Probably all of them.  If any one of these species disappeared, life on earth would still exist and your life would probably continue unchanged.  Which of the following species would you like to see lost from the world?  Which of the following species do not add to the richness and wonder of the world?  Which of the following species could be lost without the next generation regretting their loss?

fungi dragonfly
iris mountain laurel
maidenhair fern millipede