. . . similar figures would probably apply to mammals

some extinctions (or near extinctions) are easily understood . . . Great Auk, a large flightless relative of the Puffin, was killed by sailors for food on its breeding islands off the coasts of Newfoundland and Iceland (last ones killed in 1844)

some are not . . . Carolina Parakeet extinct by 1925 after a prolonged and mysterious decline -- once a common bird in the Southeast

American Bison provide a sobering example -- once perhaps numbering 60 million from North Carolina through the Rockies -- by 1850, as result of introduction of rifle and destruction of forests, bison limited to about 40 million, mostly on the Great Plains -- in 1867 and 1868 treaties with Great Plains tribes gave verbal agreement to preserving their hunting grounds in certain areas -- in 1871 manufacturers in Europe and United States discovered a way to cure bison hides to make leather and thus hunting for hides began -- in 1872 Dodge City founded (originally Buffalo City) for outfitting "buffalo" hunters and shipping hides -- hunters learned to kill 50-100 animals at a time by stalking on foot and shooting old females first

by 1874 bison exterminated in Kansas, hunters moved into Texas, treaties ignored, bloddy skirmishes with natives -- in 1874 and 1876, attempts in Congress to outlaw killing of bison failed (pocket veto by President Grant in '74, failed in Senate in '76) -- winter of 1876-77, peak of Texas slaughter, some 1500 hunters at work -- 1879, end of hunting in Texas, northern herds discovered wintering in Montana -- 1881, hunting in Montana began on large scale -- 1883, only small remnants remained -- 1886, Smithsonian Institution organized an expedition to secure specimens for their collection before the species was extinct, collected about 25 animals after intensive search in Montana

surviving bison estimated not to exceed 1000 animals, including 500 that escaped notice for many years in northern Canada, 200 in Yellowstone National Park (established by Congress in 1872 without much notice), and 300 in private ownership -- in 12 years (1871 through 1882) some 40 million bison killed (9,000/day! assuming even distribution of killing) -- bison were skinned, carcasses left to rot, in such numbers that years later many places still had piles of bleached "buffalo" bones -- after protection from hunting, bison populations recovered -- animals that eat grass (geese or bison, for example) do well if hunting is regulated

Passenger Pigeons provide another example of nearly unbelievable human rapacity -- unlike bison, they are now truly and forever extinct -- four times the size of our familiar Mourning Doves, they depended for food primarily on nuts and acorns, which trees in any one area tend to produce in large quantities every 3-4 years -- the pigeons' name comes from their dramatic movements from one feeding ground to another -- such flocks involved almost unbelievable numbers of birds -- one in Kentucky about 1805 passed overhead for more than four hours and was at least a mile wide and a number of pigeons deep (assuming modest flight speed of 25 miles/hour, this flock exceeded 100 miles X 1 mile or 300 million square yards in area and perhaps 1 billion pigeons in all . . . and such reports were not unusual

these enormous flocks would roost in square miles of forest every night during winter and fly 50-100 miles each day to feed -- roar of their wings, rain of their droppings, cracking of breaking branches masked the sounds of hundreds of guns firing all night long to kill pigeons -- these pigeons also nested in enormous aggregations, mostly in northern states where beech nuts or acorns were abundant -- one colony in Wisconsin covered 40 square miles of forest, with as many as 90 nests in one tree (perhaps 50 million nests, many other colonies this large were also reported)

these large aggregations attracted hunters (originally native Americans, later mostly market hunters) -- pigeon squabs were shipped to large cities for food -- feathers were used for bedding -- carcasses were fed to hogs

by 1800, numbers were drastically reduced east of the Appalachians, probably mostly a result of clearing the forests -- west of the mountains, the story is hard to follow, partly because large groups of pigeons moved around to find good feeding grounds, so they were abundant in one area for a while then became scarce when they moved elsewhere -- by 1870, numbers still enormous in the states around the Great Lakes -- even in 1880's, substantial aggregations nested in Wisconsin and Pennsylvania -- by 1870, however, slaughter was unmitigated -- every nesting colony and every winter roost was subjected to relentless killing -- after 1885, flocks became scarce -- in 1891, one hunter killed 2,000 -- in 1895, still reports of flocks of more than a hundred -- in 1900, last known wild Passenger Pigeon shot in Ohio -- in 1914, last bird died in Cincinnati zoo

New York passed a law protecting nesting colonies (no shooting within 1/4 mile) in 1856, Wisconsin in 1877 -- these laws evidently seldom enforced -- only state to give full protection to this species was Michigan in 1897 (!!) -- in 1909, ornithologists and conservationists could not believe the Passenger Pigeon was extinct -- offered a total of $2000 in rewards for information about nesting colonies -- with no takers!

why did this species become extinct? -- surely, not all (not even the last thousands) were killed by humans -- yet, unlike American Bison, Passenger Pigeons failed to outlast human slaughter . . .

Passenger Pigeons laid one egg a year -- low fecundity implies high survival as adults -- populations of long-lived animals can be in danger of extinction from failure to reproduce long before the last ones die (other examples today include California Condor and Wandering Albatross) -- disruption of nesting colonies must have reduced production of young birds long before a decrease in the numbers of adults was noticed -- furthermore, the forests of eastern North America were fast disappearing and with them the supplies of beech nuts and acorns

unexpected demise of the Passenger Pigeon alerted people to the risks faced by species subjected to unmitigated hunting -- stimulated more effective conservation efforts in the United States -- Lacey Act in 1894 prohibited poaching in national parks (especially elk and bison in Yellowstone)

demand for feathers for women's hats and feather boas nearly extirpated egrets and terns in the United States between 1890 and 1920 -- feathers imported by the bale from tropical countries threatened the extinction of egrets worldwide -- National Audubon Society organized to protect these birds -- two NAS wardens guarding some of the last colonies of nesting egrets in Florida and SC were shot and killed by poachers -- in response Congress finally passed the Migratory Bird Protection Act in 1918 -- prohibited killing, capturing or possessing native birds except certain game species in hunting seasons -- today egrets are again common birds -- in early 1990's NAS changed its logo on grounds that the egret is no longer a suitable symbol for conservation!! -- but they have reversed this decision

pesticides were responsible for near extirpation of Ospreys, Peregrines, Bald Eagles, Cooper's Hawks, and Brown Pelicans in U.S. -- DDT was first used in the Pacific in World War II to control mosquitos that transmit malaria -- after the war its use quickly eliminated malaria in southern Europe -- DDT (and other persistent chlorinated hydrocarbons like dieldrin and aldrin) became widely used in the 1950's for mosquito control -- DDT is not degraded or excreted by vertebrates (or invertebrates) -- accumulates in the bodies (dissolved in lipids) of long-lived predators that eat insectivorous birds or fish that injest DDT from the environment -- DDT interferes with estrogen metabolism -- in birds estrogen stimulates calcium deposition in bones prior to egg-laying for use in producing egg shells -- DDT also specifically inhibits carbonic anhydrase -- enzyme in females' oviducts necessary for deposition of calcium in the egg shell -- birds contaminated with DDT thus laid eggs with shells so thin that the birds broke them during incubation

by 1970, Ospreys, Bald Eagles, Cooper's Hawks, and Brown Pelicans had decreased to only a few reproducing pairs (the only colony of Brown Pelicans still reproducing successfully was a small one near Ocracoke Island NC which at that time was far enough from agricultural runoff contaminated with DDT) -- no breeding Peregrines remained in eastern North America -- after the ban on use of DDT in the US in 1974, Ospreys, Cooper's Hawks, and Brown Pelicans recovered dramatically -- Peregrines and Bald Eagles were laboriously re-established with birds bred in captivity -- Peregrines migrating to the tropics today still spend most of the year in habitats contaminated with DDT (American firms still export DDT to Latin America!)

habitat destruction is the major cause of extinctions in second half of this century -- Ivory-billed Woodpeckers are now extinct in the United States as a result of virtually complete destruction of the old-growth bottomland forests of the southeastern U.S. -- between 1937 and 1977, about 250,000 acres (400 square miles) of bottomland forest were cleared each year in the lower Mississippi valley -- only remaining big tracts of old-growth forest in the US are northwestern coniferous forests in northern CA, OR, WA and southeastern AK, the habitat of Spotted Owls -- most of this forest is already drastically fragmented -- preservation of the remainder is still uncertain

wetlands are another habitat disappearing fast in the U.S. -- with them are going our populations of waterfowl -- many of the ducks that winter along the coast of North Carolina breed around small marshy lakes ("potholes") in the northern Great Plains of US and Canada -- intensive agriculture has resulted in 50,000 acres of these wetlands lost each year in recent years -- loss of salt marshes along the Atlantic coast has occurred almost as fast -- continent-wide populations of Pintails (most abundant duck in North America) have dropped from 10 to 2.5 million birds in the last 30 years -- devastating floods in the Mississippi valley in the summer of 1993 also resulted in part from loss of wetlands in the northern Great Plains -- some states passed laws that restricted the draining of wetlands on the Great Plains -- new federal legislation created incentives for farms in the Great Plains to preserve wetlands -- some populations of ducks are recovering

there are cases in which local sedentrary populations of humans have managed some resources for long-term benefits of the individuals involved ... Cree (and other native American groups of the northern forest belt) have individual trapping territories, some communities of lobster fishermen in Maine have individual trapping territories, some local organizations of ranchers have managed their individual use of nearby public rangelands for long-term benefits ... these groups fit the conditions for prudent predation by wolf packs ... or for stable cooperation among individuals

study questions . . .