How do organisms become threatened, endangered, or extinct?

Overview Questions Why should we care about protecting wild species? Which human activities endanger wildlife? How can we help prevent premature extinction of species?

Core Case Study: The Passenger Pigeon - Gone Forever Once the most numerous bird on earth. In 1858, Passenger Pigeon hunting became a big business. By 1900 they became extinct from over-harvest and habitat loss.

SPECIES EXTINCTION Species can become extinct: Locally: A species is no longer found in an area it once inhabited but is still found elsewhere in the world. Ecologically: Occurs when so few members of a species are left they no longer play its ecological role. Globally (biologically): Species is no longer found on the earth.

Global Extinction Some animals have become prematurely extinct because of human activities.

Endangered and Threatened Species: Ecological Smoke Alarms Endangered species: so few individual survivors that it could soon become extinct. Threatened species: still abundant in its natural range but is likely to become endangered in the near future.

Grizzly bear Kirkland’s warbler Knowlton cactus African elephant Florida manatee Figure 11.3 Endangered natural capital: species that are endangered or threatened with premature extinction largely because of human activities. Almost 30,000 of the world’s species and 1,260 of those in the United States are officially listed as being in danger of becoming extinct. Most biologists believe the actual number of species at risk is much larger. Utah prairie dog Swallowtail butterfly Humpback chub Siberian tiger Golden lion tamarin Almost 30,000 of the world’s species and 1,260 of those in the United States are officially listed as being in danger of becoming extinct. Most biologists believe the actual number of species at risk is much larger.

Giant panda Black-footed ferret Whooping crane Northern spotted owl Blue whale Figure 11.3 Endangered natural capital: species that are endangered or threatened with premature extinction largely because of human activities. Almost 30,000 of the world’s species and 1,260 of those in the United States are officially listed as being in danger of becoming extinct. Most biologists believe the actual number of species at risk is much larger. Mountain gorilla Florida panther California condor Hawksbill sea turtle Black rhinoceros

SPECIES EXTINCTION Some species have characteristics that make them vulnerable to ecological and biological extinction.

SPECIES EXTINCTION Scientists use measurements and models to estimate extinction rates. The International Union for the Conservation of Nature and Natural Resources (IUCN) publishes an annual Red List, listing the world’s threatened species. The 2004 Red List contains 15,589 species at risk for extinction.

SPECIES EXTINCTION Figure 11.5 Endangered natural capital: percentage of various types of species threatened with premature extinction because of human activities. QUESTION: Why do you think fish top this list? (Data from World Conservation Union, Conservation International, and World Wildlife Fund) Percentage of various species types threatened with premature extinction from human activities.

SPECIES EXTINCTION Scientists use models to estimate the risk of particular species becoming extinct or endangered.

IMPORTANCE OF WILD SPECIES We should not cause the premature extinction of species because of the economic and ecological services they provide. Some believe that each wild species has an inherent right to exist. Some people distinguish between the survival rights among various types of species (plants vs. animals).

HABITAT LOSS, DEGRADATION, AND FRAGMENTATION Conservation biologists summarize the most important causes of premature extinction as “HIPPO”: Habitat destruction, degradation, and fragmentation Invasive species Population growth Pollution Overharvest

HABITAT LOSS, DEGRADATION, AND FRAGMENTATION Figure 11.7 Natural capital degradation: underlying and direct causes of depletion and premature extinction of wild species. The major direct cause of wildlife depletion and premature extinction is habitat loss, degradation, and fragmentation. This is followed by the deliberate or accidental introduction of harmful invasive (nonnative) species into ecosystems. The greatest threat to a species is the loss, degradation, and fragmentation of where it lives. This is followed by the deliberate or accidental introduction of harmful invasive (nonnative) species into ecosystems.

HABITAT LOSS, DEGRADATION, AND FRAGMENTATION Reduction in ranges of four wildlife species, mostly due to habitat loss and overharvest.

Indian Tiger Range 100 years ago Range today (about 2,300 left) Figure 11.8 Natural capital degradation: reductions in the ranges of four wildlife species, mostly as the result of habitat loss and hunting. What will happen to these and millions of other species when the world’s human population doubles and per capita resource consumption rises sharply in the next few decades? (Data from International Union for the Conservation of Nature and World Wildlife Fund) Range 100 years ago Range today (about 2,300 left)

Black Rhino Range in 1700 Range today (about 3,600 left) Figure 11.8 Natural capital degradation: reductions in the ranges of four wildlife species, mostly as the result of habitat loss and hunting. What will happen to these and millions of other species when the world’s human population doubles and per capita resource consumption rises sharply in the next few decades? (Data from International Union for the Conservation of Nature and World Wildlife Fund) Range in 1700 Range today (about 3,600 left)

African Elephant Probable range 1600 Range today Figure 11.8 Natural capital degradation: reductions in the ranges of four wildlife species, mostly as the result of habitat loss and hunting. What will happen to these and millions of other species when the world’s human population doubles and per capita resource consumption rises sharply in the next few decades? (Data from International Union for the Conservation of Nature and World Wildlife Fund) Probable range 1600 Range today

Asian or Indian Elephant Figure 11.8 Natural capital degradation: reductions in the ranges of four wildlife species, mostly as the result of habitat loss and hunting. What will happen to these and millions of other species when the world’s human population doubles and per capita resource consumption rises sharply in the next few decades? (Data from International Union for the Conservation of Nature and World Wildlife Fund) Former range Range today (34,000–54,000 left)

Case Study: A Disturbing Message from the Birds Human activities are causing serious declines in the populations of many bird species.

Golden-cheeked warbler The 10 most threatened species of U.S. songbirds, according to a 2002 study by the National Audubon Society. Most of these species are vulnerable because of habitat loss and fragmentation from human activities. An estimated 12% of the world’s known bird species may face premature extinction from human activities during this century. Cerulean warbler Sprague’s pipit Bichnell’s thrush Black-capped vireo Golden-cheeked warbler Figure 11.10 Threatened natural capital: the 10 most threatened species of U.S. songbirds, according to a 2002 study by the National Audubon Society. Most of these species are vulnerable because of habitat loss and fragmentation from human activities. An estimated 12% of the world’s known bird species may face premature extinction from human activities during this century. (Data from National Audubon Society) Florida scrub jay California gnatcatcher Kirtland’s warbler Henslow’s sparrow Bachman’s warbler

Case Study: A Disturbing Message from the Birds The majority of the world’s bird species are found in South America. Threatened with habitat loss and invasive species.

INVASIVE SPECIES Many nonnative species provide us with food, medicine, and other benefits but a few can wipe out native species, disrupt ecosystems, and cause large economic losses. Kudzu vine was introduced in the southeastern U.S. to control erosion. It has taken over native species habitats.

INVASIVE SPECIES Many invasive species have been introduced intentionally.

INVASIVE SPECIES Many invasive species have been introduced unintentionally.

More than 7,100 harmful invasive (nonnative) species that have been deliberately or accidentally introduced into the United States. Deliberately Introduced Species Purple loosestrife European starling African honeybee (“Killer bee”) Nutria Salt cedar (Tamarisk) Figure 11.11 Threats to natural capital: some of the more than 7,100 harmful invasive (nonnative) species that have been deliberately or accidentally introduced into the United States. Marine toad (Giant toad) Japanese beetle Hydrilla European wild boar (Feral pig) Water hyacinth

Accidentally Introduced Species Sea lamprey (attached to lake trout) Argentina fire ant Brown tree snake Eurasian ruffe Common pigeon (Rock dove) Figure 11.11 Threats to natural capital: some of the more than 7,100 harmful invasive (nonnative) species that have been deliberately or accidentally introduced into the United States. Formosan termite Zebra mussel Asian long-horned beetle Asian tiger mosquito Gypsy moth larvae

INVASIVE SPECIES The Argentina fire ant was introduced to Mobile, Alabama in 1932 from South America. Most probably from ships. No natural predators.

• Do not allow wild animals to escape. What Can You Do? Invasive Species • Do not allow wild animals to escape. • Do not spread wild plants to other areas. • Do not dump the contents of an aquarium into waterways, wetlands, or storm drains. • When camping use wood near your campsite instead of bringing firewood from somewhere else. • Do not dump unused bait into the water. • After dogs visit woods or the water brush them before taking them home. • After each use clean your vehicle, mountain bike, surfboard, kayaks, canoes, boats, tent, hiking boots, and other gear before heading for home. • Empty all water from canoes, kayaks, dive gear, and other outdoor equipment before heading home. • Plant a variety of trees, shrubs, and other plants in your yard to reduce losses from invasive species. • Do not buy plants from overseas or swap them with others using the Internet. Figure 11.14 Individuals matter: ways to prevent or slow the spread of harmful invasive species. QUESTIONS: Which two of these actions do you think are the most important? Which of these actions do you plan to take?

Ecosystems Vulnerable Characteristics of Successful Invader Species Characteristics of Ecosystems Vulnerable to Invader Species • High reproductive rate, short generation time (r-selected species) • Pioneer species • Long lived • High dispersal rate • Release growth-inhibiting chemicals into soil • Generalists • High genetic variability • Climate similar to habitat of invader • Absence of predators on invading species • Early successional systems • Low diversity of native species • Absence of fire • Disturbed by human activities Figure 11.13 Threats to natural capital: some general characteristics of successful invasive species and ecosystems vulnerable to invading species.

POPULATION GROWTH, POLLUTION, AND CLIMATE CHANGE Population growth, affluenza, and pollution have promoted the premature extinction of some species. Projected climate change threatens a number of species with premature extinction.

Pollution Each year pesticides: Kill about 1/5th of the U.S. honeybee colonies. 67 million birds. 6 -14 million fish. Threaten 1/5th of the U.S.’s endangered and threatened species. Example of biomagnification of DDT in an aquatic food chain.

DDT in fish-eating birds (ospreys) 25 ppm DDT in large fish (needle fish) 2 ppm DDT in small fish (minnows) 0.5 ppm Figure 11.15 Natural capital degradation: bioaccumulation and biomagnification. DDT is a fat-soluble chemical that can accumulate in the fatty tissues of animals. In a food chain or web, the accumulated DDT can be biologically magnified in the bodies of animals at each higher trophic level. The concentration of DDT in the fatty tissues of organisms was biomagnified about 10 million times in this food chain in an estuary near Long Island Sound in New York. If each phytoplankton organism takes up from the water and retains one unit of DDT, a small fish eating thousands of zooplankton (which feed on the phytoplankton) will store thousands of units of DDT in its fatty tissue. Each large fish that eats 10 of the smaller fish will ingest and store tens of thousands of units, and each bird (or human) that eats several large fish will ingest hundreds of thousands of units. Dots represent DDT, and arrows show small losses of DDT through respiration and excretion. DDT in zooplankton 0.04 ppm DDT in water 0.000003 ppm, or 3 ppt

OVEREXPLOITATION Some protected species are killed for their valuable parts or are sold live to collectors. Killing predators and pests that bother us or cause economic losses threatens some species with premature extinction. Legal and illegal trade in wildlife species used as pets or for decorative purposes threatens some species with extinction.

OVEREXPLOITATION Rhinoceros are often killed for their horns and sold illegally on the black market for decorative and medicinal purposes.

Case Study: Rising Demand for Bushmeat in Africa Bushmeat hunting has caused the local extinction of many animals in West Africa. Can spread disease such as HIV/AIDS and ebola virus.

PROTECTING WILD SPECIES: LEGAL AND ECONOMIC APPROACHES International treaties have helped reduce the international trade of endangered and threatened species, but enforcement is difficult. One of the most powerful is the 1975 Convention on International Trade of Endangered Species (CITES). Signed by 169 countries, lists 900 species that cannot be commercially traded.

Case Study: The U.S. Endangered Species Act One of the world’s most far-reaching and controversial environmental laws is the 1973 U.S. Endangered Species Act (ESA). ESA forbids federal agencies (besides defense department) to carry out / fund projects that would jeopardize an endangered species. ESA makes it illegal for Americans to engage in commerce associated with or hunt / kill / collect endangered or threatened species.

Case Study: The U.S. Endangered Species Act Biodiversity hotspots in relation to the largest concentrations of rare and potentially endangered species in the U.S.

3 Southern Appalachians 4 Death Valley 5 Southern California Top Six Hot Spots 1 Hawaii 2 San Francisco Bay area 3 Southern Appalachians 4 Death Valley 5 Southern California 6 Florida Panhandle Figure 11.18 Threatened natural capital: biodiversity hot spots in the United States. The shaded areas contain the largest concentrations of rare and potentially endangered species. Compare these areas with those on the map of the human ecological footprint in North America shown in Figure 4 on pp. S14–S15 in Supplement 4. (Data from State Natural Heritage Programs, the Nature Conservancy, and Association for Biodiversity Information) Concentration of rare species Low Moderate High

Endangered Species Because of scarcity of inspectors, probably no more than 1/10th of the illegal wildlife trade in the U.S. is discovered.

Endangered Species Congress has amended the ESA to help landowners protect species on their land. Some believe that the ESA should be weakened or repealed while others believe it should be strengthened and modified to focus on protecting ecosystems. Many scientists believe that we should focus on protecting and sustaining biodiversity and ecosystem function as the best way to protect species.

How Would You Vote? To conduct an instant in-class survey using a classroom response system, access “JoinIn Clicker Content” from the PowerLecture main menu for Living in the Environment. Should the Endangered Species Act be modified to protect and sustain the nation's overall biodiversity? a. No. Protecting entire habitats will only further interfere with the rights of landowners. b. Yes. Protecting endangered habitats is more efficient and effective than saving individual species.

PROTECTING WILD SPECIES: THE SANCTUARY APPROACH The U.S. has set aside 544 federal refuges for wildlife, but many refuges are suffering from environmental degradation. Pelican Island was the nation’s first wildlife refuge.

PROTECTING WILD SPECIES: THE SANCTUARY APPROACH Gene banks, botanical gardens and using farms to raise threatened species can help prevent extinction, but these options lack funding and storage space. Zoos and aquariums can help protect endangered animal species by preserving some individuals with the long-term goal of reintroduction, but suffer from lack of space and money.

RECONCILIATION ECOLOGY Reconciliation ecology involves finding ways to share places we dominate with other species. Replacing monoculture grasses with native species. Maintaining habitats for insect eating bats can keep down unwanted insects. Reduction and elimination of pesticides to protect non-target organisms (such as vital insect pollinators).

Using Reconciliation Ecology to Protect Bluebirds Putting up bluebird boxes with holes too small for (nonnative) competitors in areas where trees have been cut down have helped reestablish populations.

What Can You Do? Protecting Species • Do not buy furs, ivory products, and other materials made from endangered or threatened animal species. • Do not buy wood and paper products produced by cutting remaining old-growth forests in the tropics. • Do not buy birds, snakes, turtles, tropical fish, and other animals that are taken from the wild. • Do not buy orchids, cacti, and other plants that are taken from the wild. • Spread the word. Talk to your friends and relatives about this problem and what they can do about it. Figure 11.21 Individuals matter: ways to help premature extinction of species. QUESTIONS: Which two of these actions do you think are the most important? Which of these actions do you plan to take?