Environmental Problems, Their Causes, and Sustainability 1

North American–SouthAmerican flywaysEuropean–AfricanflywaysAsian flywaysFigure 12-15 Natural capital: major flyways used by migratory birds, mostly waterfowl. Each route has anumber of subroutes. Some countries along such flyways have entered into agreements and treaties to protectcrucial habitats, especially wetlands, needed by such species, both along their migration routes and at eachend of their journeys.than 100 seed banks have focused on storing seeds ofthe approximately 100 plant species that provide uswith food—with just 14 plants providing about 90% ofthe calories in our food. Some banks are beginning tostore seeds for a wider range of species that may bethreatened with extinction or a loss of genetic diversity.Scientists urge the establishment of many moresuch banks, especially in developing countries.But seed banks are expensive to operate and canbe destroyed by accidents. Also, because stored seedsdo not evolve, they may not survive when used in thefuture.The world’s 1,600 botanical gardens and arboretumscontain living plants, representing almost one-third ofthe world’s known plant species. However, they containonly about 3% of the world’s rare and threatenedplant species.Botanical gardens also help educate an estimated150 million visitors a year about the need for plantconservation. But these sanctuaries have too little storagecapacity and too little funding to preserve most ofthe world’s rare and threatened plants.We can take pressure off some endangered orthreatened species by raising them on farms for commercialsale. One example is the use of farms inFlorida to raise alligators for meat and hides. Anotherexample is butterfly farms in Papua New Guinea, wheremany butterfly species are threatened by habitat destructionand fragmentation, commercial overexploitation,and environmental degradation.Can Zoos and Aquariums Help Protect MostEndangered Animal Species? Important butExpensive and LimitedZoos and aquariums can help protect endangeredanimal species, but lack funding and storage space.Zoos, aquariums, game parks, and animal researchcenters are being used to preserve some individuals ofcritically endangered animal species, with the longtermgoal of reintroducing the species into protectedwild habitats. Two techniques for preserving endangeredterrestrial species are egg pulling and captivebreeding. Egg pulling involves collecting wild eggs laidby critically endangered bird species and then hatchingthem in zoos or research centers. In captive breeding,some or all of the wild individuals of a critically endangeredspecies are captured for breeding in captiv-246 CHAPTER 12 Sustaining Biodiversity: The Species Approach