Environmental Problems, Their Causes, and Sustainability 1

spend over three times as many hours watchingwildlife—doing nature photography and bird watching,for example—as they spend on watching moviesor professional sporting events.Wildlife tourism, or eco-tourism, generates at least$500 billion per year worldwide, and perhaps twicethat much. Conservation biologist Michael Soulé estimatesthat one male lion living to age 7 generates$515,000 in tourist dollars in Kenya but only $1,000 ifkilled for its skin. Similarly, over a lifetime of 60 yearsa Kenyan elephant is worth about $1 million in ecotouristrevenue—many times more than its tusks areworth when sold illegally for their ivory.Ideally, eco-tourism should not cause ecologicaldamage. In addition, it should provide income for localpeople to motivate them to preserve wildlife andfunds for the purchase and maintenance of wildlifepreserves and conservation programs. Much ecotourismdoes not meet these standards, and excessiveand unregulated eco-tourism can destroy or degradefragile areas and promote premature species extinction.The website for this chapter lists some guidelinesfor evaluating eco-tours.Case Study: Why Should We Care about Bats?Ecological AlliesBecause of the important ecological and economicroles bats play, we should view them as valuableallies, not as enemies to kill.Worldwide there are 950 known species of bats—theonly mammals that can fly. However, bats have twotraits that make them vulnerable to extinction. First,they reproduce slowly. Second, many bat species livein huge colonies in caves and abandoned mines,which people sometimes block. This prevents themfrom leaving to get food and can disturb theirhibernation.Bats play important ecological roles. About 70% ofall bat species feed on crop-damaging nocturnal insectsand other insect pest species such as mosquitoes.This makes them the major nighttime SWAT team forsuch insects.In some tropical forests and on many tropical islands,pollen-eating bats pollinate flowers, and fruiteatingbats distribute plants throughout tropical forestsby excreting undigested seeds.As keystone species, such bats are vital for maintainingplant biodiversity and for regenerating largeareas of tropical forest cleared by human activities. Ifyou enjoy bananas, cashews, dates, figs, avocados, ormangos, you can thank bats.Many people mistakenly view bats as fearsome,filthy, aggressive, rabies-carrying bloodsuckers. Butmost bat species are harmless to people, livestock, andcrops. In the United States, only 10 people have died ofbat-transmitted disease in four decades of recordkeeping; more Americans die each year from fallingcoconuts.Because of unwarranted fears of bats and lack ofknowledge about their vital ecological roles, severalbat species have been driven to extinction. Currently,about one-fourth of the world’s bat species, includingthe ghost bat (Figure 12-3), are listed as endangered orthreatened. Conservation biologists urge us to viewbats as valuable allies, not as enemies.What Is the Intrinsic Value of Species?Existence RightsSome people believe that each wild species has aninherent right to exist.Some people believe that each wild species also has intrinsicor existence value based on its inherent right toexist and play its ecological roles regardless of its usefulnessto us. Biologist Edward O. Wilson believesmost people feel obligated to protect other species andthe earth’s biodiversity because most humans seem tohave a natural affinity for nature that he calls biophilia(Connections, right). As novelist Fyodor Dostoevskysaid in his 1889 novel The Brothers Karamazov, “Lovethe animals, love the plants, love everything. If youlove everything, you will perceive the divine mysteryin things. Once you perceive it, you will begin to comprehendit better every day. And you will come at lastto love the whole world with an all-embracing love.”Some people distinguish between the survivalrights of plants and those of animals, mostly for practicalreasons. Poet Alan Watts once said he was a vegetarian“because cows scream louder than carrots.”Other people distinguish among various types ofspecies. For example, they might think little about gettingrid of the world’s mosquitoes, cockroaches, rats,or disease-causing bacteria.Some proponents of existence rights such as NobelPrize winner Albert Schweitzer go further and assertthat each individual organism has a right to survivewithout human interference. Others apply this to individualsof some species but not to those of other species.Unless they are strict vegetarians, for example, somepeople see no harm in having others kill domesticatedanimals in slaughterhouses to provide them with meat,leather, and other products. But these same peoplemight deplore the killing of wild animals such as deer,squirrels, or rabbits. Where do you stand on this issue?Some conservation biologists also caution us notto focus primarily on protecting relatively big organisms—theplants and animals we can see and are familiarwith. They remind us that the true foundationof the earth’s ecosystems and ecological processes arethe invisible bacteria, and the algae, fungi, and othermicroorganisms that decompose the bodies of larger organismsand recycle the nutrients needed by all life(Case Study, p. 56).230 CHAPTER 12 Sustaining Biodiversity: The Species Approach