Where the Wild Things Were: Life, Death, and Ecological Wreckage in a Land of Vanishing Predators, is a new and important contribution to conservation and ecology by William Stolzenburg (Bloomsbury, 2008)
The author looks at cases, both experimental and real-life, where the top predators have been wiped out, and looks at what happens next. It turns out that a lot of things happen, none of them good. One result is an explosion of "mesopredators" (the second-tier carnivores, ranging from coyotes to raccoons to feral domestic cats) which wreak havoc on ecosystems without the larger predators to compete with (and sometimes eat) them. Plants and prey animals have evolved for one type of ecosystem and are often helpless in an altered one. While his examples come from all over the world, it's the North American ones that will cause the most consternation to most readers. Who foresaw that killing the eastern wolves and cougars would result in a gigantic deep population explosion that wrecked the habitats of many smaller creatures? Who knew that bringing in a new apex predator (whalers) wiping out the northern Pacific great whales started a cascade that drove the former apex predator (killer whales) to decimate seal and sea otter populations in many areas, resulting in kelp forests being replaced by barren seafloor overrun with the urchins the otters used to keep down? There are many such examples, some almost despair-inducing. One of Stolzenburg's other important points is that, ecologically, human hunters don't replace the predators: they hunt in specific seasons rather than all year round and pick off the largest animals instead of the weakest.
COMMENT: He doesn't use this example, but there's an obvious application in the case of Alaska's wolves. Alaska governor and Republican VP candidate Sarah Palin (who I personally like overall) is one of the officials who has bought into the argument that killing wolves means more moose for hunters. Well, it does, but it will also have many other repercussions on an ecosystem which relies on the wolves to keep moose numbers reasonable.