| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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life on the edge In Tooth and Claw
Between the demise of Tyrannosaurus rex and the advent of technology, no animal has reigned so supreme in its environment as the killer whale. If there had been any doubt as to who was the master of the seas, it was put to rest-along with a great white shark-in October 1997, when whalewatchers on an Oceanic Society vessel saw a killer whale make mincemeat of that fearsome fish. See www.cnn.com/ EARTH/9710/08/ whale.vs.shark/ In this issue two photographers describe their experiences beside very different pods of orcas feeding on their chosen fare. The accounts have elements in common. In both cases the killer whales, Orcinus orca, act as a coordinated group, with each animal playing a specific role. Yet their quarries are entirely different. James Michael Dorsey and his companions quietly paddling in their kayaks watch "residents," orcas who spend most of their lives in a specific geographical locale and eat primarily fish. Dorsey feels quite safe in his flimsy craft while a whole school of salmon is maneuvered to destruction. Todd Pusser on a zodiac in Monterey Bay is witness to a far more gruesome scene. There these mammals live up to their name, for they are killers of whales. Termed "transients," of no fixed address, their diet appears to consist entirely of mammals: seals, sea lions, sometimes tiny sea otters, and whales. Not only do these two "kinds" of whales have different diets, they are also distinguishable by their appearance. The saddle patches of the transients are always solid white, and their dorsal fins sharper. To capture their contrasting prey, they have different hunting methods. Transients hunt in small groups and, prior to the initial attack, they are silent. Genetic studies show that residents and transients have not interbred for a very long time and most experts consider them at least separate subspecies. Death seems to feature prominently in this issue. While the feeding habits of orcas have not been generally influenced by human activities, that cannot be said of our role in the other stories. It was an airplane that brought West Nile virus to the Americas. Sadly, this threat to humans and wildlife is unlikely to go away, at least not in our lifetimes. Gordy Slack in "A Murder of Crows" explains that the virus presents us with an ongoing dilemma. Even mosquitoes play a crucial role in a healthy ecosystem, as do other animals that would be killed by the large-scale application of insecticides The introduction of West Nile was at least inadvertent, unlike the racket from manmade noises. Cameron Walker, in "Killing Me Loudly," catalogs how intrusive sounds cause fear and confusion among wildlife and disrupt their lives. The noise from airplanes or snowmobiles is incidental to the activity. But in the case of underwater sonar, it is the blasts of sound themselves that the navy deems important, while the beachings and deaths of disoriented whales are so much byproduct. But the most dramatic deaths we describe in this issue are those of bear admirers Timothy Treadwell and Anne Huguenard in "Who Lives By the Bear." Despite their intimate knowledge of bears, both fell prey to a grizzly whose behavior they did not anticipate, and by their deaths underscored the unpredictable nature of wildness. But death does bring renewal. Though dying trees, starved for water, were a critical cause of the disastrous fires around San Diego in 2003, Deborah Knight, in "Fire Followers," writes that as soon as the conflagration was over, nature was ready to restore life to the charred hillsides. And man and nature together are making up for past and current excesses, farming sustainable sturgeon ("California Caviar") and bringing back the "Oly," the oyster native to San Francisco Bay ("Horizons") after those tasty morsels were all but wiped out in the nineteenth century. Keith K. Howell is Editor of California Wild. |