There are about 1.5 million species which are known to exist on earth.  The number of as yet undescribed species is probably greater than the number already known to exist.  Why are there so many different species? Although there are widespread generalist species which are found throughout the world, most species only exist in certain parts of the world and often depend on food sources and environmental conditions which are specific to that part of the world.

For example, in comparing the wildlife of the Northeastern United States and central South America, there are different species of deer.


There are wild pigs (peccaries) which are found in Paraguay which do not exist in the Northeast, including the endangered tagua (the second image) which can only be found in the central South American region known as the Chaco.


North America possesses hoofed animals which are not found in South America such as bison.


Rodents such as beaver are native to North America while capybaras are native to South America.


While there are a handful of species of warbler in central South America, the majority of species are native to North America (and winter in Northern Latin America).


While there are a handful of species of flycatcher in the Northeast U.S., more than one hundred are native to central South America.


While the ruby-throated hummingbird is the only species of hummingbird found east of the Mississippi River, the small country of Paraguay is home to more than a dozen species of hummingbird.


The woodpeckers of North America


differ from those of South America.


The birds found in aquatic environments in central South America are different from those one would find in the Northeastern U.S.




No matter what groups of organisms were considered, those of central South America would be distinct from those of the Northeast U.S.


caimanworm lizard



tree fernflower



Because biomes vary across the world or across the country, one finds many organisms occurring only in certain areas. Within the United States, for example, there is great variation in the native species of birds.

1) the east coast: great black-backed gull, surf & white-winged scoters, black-bellied plover, purple sandpiper, Louisiana heron, white ibis, glossy ibis, tufted duck, whistling swan, red-necked grebe,

2) the Northeast: chestnut-sided warbler, golden-winged warbler, alder flycatcher, magnolia warbler, black-throated green warbler, blackburnian warbler, black-throated blue warbler

3) grasslands: greater prairie chicken, gray partridge, lark bunting, chestnut-collared, McCown's, & Smith's longspurs, 

4) Fla:brown noddy, black noddy, magnificent frigatebird, swallow-tailed kite (Georgia also), wood stork, great white heron, limpkin, short-tailed hawk, everglade kite, spotted-breasted oriole, gray kingbird, blue-gray tanager, black-whiskered vireo, mangrove cuckoo, red-whiskered bulbul, smooth billed ani

5) Texas:whooping crane (50 individuals), least grebe, green kingfisher, white tailed hawk, black-capped vireo, jacana, scaled quail, chachalaca, pauraque, white-winged dove, cave swallow, golden-fronted woodpecker, black-headed oriole, kiskadee flycatcher, yellow green vireo, black-crested titmouse, buff-bellied hummingbird 

6) New England: common eider,  mourning warbler, spruce grouse, hawk owl, boreal owl, bay-breasted warbler, yellow throated flycatcher, gray-cheeked thrush, boreal chickadee, blackpoll warbler



     About one quarter of the earth’s mammals and reptiles, 21% of amphibians, 30% of fish, and 12% of the earth’s birds are in danger of extinction.  The loss of habitat is the greatest threat to 85% of the earth’s most threatened birds.  About 1/3 of parrot species are endangered by habitat loss and collecting for pets or plumage.

     Many populations now exist in such small numbers that they are in danger of extinction.  Some occur in New York such as the Indiana Bat, Karner Blue Butterfly, Piping Plover, Eastern Puma, Shortnose Sturgeon, Dwarf Wedgemussel and the Eastern Sandplain Gerardia (a flower).  The humpback and right whales and hawksbill, Kemps Ridley, Leatherback, and Loggerhead sea turtles are also in danger of extinction; they can be found off the coast of New York.  A number of New York species are threatened (not as critical as endangered) including the bald eagle, lynx, bog turtle, Chittenango ovate amber snail, and 4 species of plants.



   The maps above depicted the limited distribution of many species globally.


II)                  MANY OF THE ENDANGERED ORGANISMS FOUND IN THE U.S. ARE SO SPECIFIC THAT THEIR HABITAT IS LIMITED TO ONE OR TWO STATES (abbreviations of the states follow the name of the organism):


1)     MAMMALS

--Columbia White Tail Deer: WA & OR

--Key Deer: FL

--San Joaquin Kit Fox: CA

--Jaguarundi: one subspecies TX, the other AR

--Hawaiian Hoary Bat: HI

--Mariana Fruit Bat: Guam

--6 species of Kangaroo Rat (Fresno, Giant, Morro Bay, Stephens, Tripton, San Bernardino Merriams): CA


2)     BIRDS

--Hawaii has a great diversity of birds that occur only there an nowhere else in the world; those that are endangered include the Nihoa Millerbird, Palila, Moorhen, Nukupu’u, and two species of ‘O’u

--Puerto Rican parrot, Puerto Rican nightjar, Puerto Rican plain pigeon: Puerto Rico

--Northern Spotted Owl: CA, OR, WA

--Atwaters Greater Prairie Chicken: TX

--Cactus ferrugineous Pygmy Owl: AZ

--San Clemente Shrike, California Least Tern, California and Light Footed Clapper Rails: CA

--Guam Rail: Guam

--Florida Scrub Jay, Florida Grasshopper Sparrow, Cable Seaside Sparrow: Florida



--Bluetail Skink, Sand Skink, Atlantic Saltwater Marsh Snake: Florida

--Almaeda Whipsnake, Giant Garter Snake: California

--Concho Water Snake: TX

--Lake Erie Water Snake: OH (and Ontario)

--Alabama Redbelly Turtle, Flattened Musk Turtle: Alabama

--Plymouth Redbelly Turtle: MA

--Yellow Blotched Map Turtle: MS



--Barton Springs Salamander: TX

--Cheat Mountain Salamander: WV

--California Tiger Salamander: CA

--Red Hills Salamander: AL

--Shenandoah Salamander: VA

--Houston Toad: TX

--Puerto Rican Crested Toad: Puerto Rico

--Wyoming Toad: Wyoming


5)     FISH

--Pygmy and Smoky Madtom: TN

--Pahrump Poolfish, Devils Hole and Ash Meadows Pupfish: NV

--Comanche Springs Pupfish: CA

--Chum Salmon: VA

--Coho Salmon: CA

--Pygmy Sculpin and Cahaba Shiner: AL

--Cape Fear Shiner and Waccamaw Silverfish: NC

--Pecos Bluntnose Shiner: NM

--Little Coloroado Spinedace: AZ

--Steelhead: OR, WA

--June Sucker: UT

--Warner Sucker: OR

--Greenback Trout: CO


6)     INVERTEBRATES (Spiders and Clams as examples)

--Bone Cave Harvestman, Bee Creek Cave Spider, Tooth Cave Pseudoscorpion: TX

--Spruce-fir Moss Spider: NC, TN

--Speckled Pocketbook, Arkansas Fatmucket: AR

--Carolina Heelsplitter: NC & SC

--Louisiana Pearlshell: LA
–Cumberland Pigtoe: TN

--Dark Pigtoe: AL

--James Spinymussel: VA & WV
Spinymussel: NC



--Brittons Beargrass, Amargosa Niterwort, White Birds in a Nest: FL

--San Clemente Island Bush Mallow, Santa Cruz Island and Island Malocothrix: CA

--Mohrs Barbaras Buttons: AL & GA

--a great diversity of plants native to Hawaii including many species of Alani

--Michigan Monkey-Flower: MI

--Macfarlanes 4-o’clock: ID, OR

--Fassets Locoweed: WI

--Brady Pincushion Cactus:AZ

--Peebles Navajo Cactus and San Rafael Cactus: UT

--Blowout Penstemon: NE

--Penland Beardtongue: CO

--Texas Trailing Phlox: TX

--Godfrey’s Butterwort: FL




The above land in Paraguay was once subtropical forest, now it is pasture for cattle.


This region in Paraguay was a unique thorn forest-scrubland called the Chaco which is an arid habitat in central South America.  The above picture depicts one region which was deforested to provide more cattle pasture.

  Although the following picture depicts forest of the Northeast U.S.,it is very different from the virgin old-growth forests full of hundred foot trees which once existed there.


    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. Mangrove swamps once covered more than 200,000 square kilometers of coastline. This area is being lost at a rate of 1-2% per year and mangroves are approaching extinction in 26 of the 120 countries where they are found (Duke, 2007).

     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).

 Many animals which inhabit deep woods habitats are threatened when a habitat is fragmented, not only because the physical area that they can inhabit is reduced, but also because new species are introduced into the area which compete with them. This is especially evident in the case of brown-headed cowbirds.

The brown headed cowbird parasitizes other birds by laying its eggs in their nests. Other birds raise the cowbirds as their own and the cowbird nestlings outcompete those of the other species. This brood parasitism can decrease the populations of songbirds by half. The brown headed cowbird originally inhabited western North America but expanded its populations eastward when forests were cleared. They prefer edge habitats so that the splitting of a large region of continuous forest into smaller habitats drastically increases the effect of cowbirds on forest birds.


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.