Agenda - 09-29-1999 - 9e - Laserfiche WebLink

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species can occupy a limited area of habitat. Sometimes there is not enough food or other necessities for more individuals to exist there; sometimes each individual defends some or all of the area it occupies against others of the same species. Either way, the larger an area the larger the number of individuals that can live and reproduce there. This limitation on the number of individu- als that an area can support exposes a frequent misunderstanding about wildlife. When a forest is cut, the animals living there cannot usually go somewhere else to live. Everywhere else already has a full population of individuals. When wildlife habitat is destroyed, the displaced indi- viduals have lost their livelihood. There are no refugees following loss of habitat for wildlife. The only way to assure that wildlife survives is to preserve their habitats. CONNECTIONS ARE IMPORTANT Large size of forests is important for another reason as well, one that might apply more to wildlife other than birds. Small tracts of forest inevitably include only a few individuals of each species. If these individuals cannot move around as easily as birds, each tract of forest becomes an isolated "island". For Box Turtles and Spotted Salamanders, for instance, few individuals or in some cases none can make the trek from one patch of forest inhospitable areas. Some of the intervening areas are potentially deadly as a result of automobiles on roads. Just as important is exposure to preda- tors or dessication in the open. In addition, some intervening areas, like riprap around bridges across streams, are physically impossible for some animals to cross. Many animals simply will not venture into such inhospitable habitats. Small isolated patches of forest contain small isolated populations of animals and plants. Biologists have repeatedly documented the consequences of small sizes for populations. Over generations, small populations lose genetic vari- ability. They thus lose flexibility in adapting to variations and changes in habitats. In addition, unpredictable fluctuations in the numbers of individuals in a small population are more likely to lead to a population of zero individuals — in other words, to local extinction. Local extinction of a species in an isolated island of habitat is ly to be reversed by immigrants from other ces. So small populations disappear one by one as each takes an unpredicted hit. The best way to avoid these conse- quences of small populations is to maintain large tracts of suitable habitat. The second best way is to preserve connections or corridors between Is of suitable habitat. These connections 7