Fearing predators is a learned behavior, study says
WCS
June 20, 2007
Are Asian elk hard-wired to fear the Siberian tigers who stalk them? When wolves disappear from the forest, are moose still afraid of them?
No, according to a study by Wildlife Conservation Society scientist Dr. Joel Berger, who says that several large prey species, including moose, caribou and elk, only fear predators they regularly encounter. If you take away wolves, you take away fear. That is a critical piece of knowledge as biologists and public agencies increase efforts to re-introduce large carnivores to places where they have been exterminated. Berger's study is published in the latest issue of the journal Conservation Biology.
Invasive predators more harmful to biodiversity than native predators.
Alien predators are more harmful to prey populations than native predators, reports a study published in the current issue of the journal Proceedings of the Royal Society B: Biological Sciences. Analyzing prey response across dozens of field experiments in New Zealand, Australia, and island ecosystems, an international team of researchers led by Pälvi Salo of the University of Turku in Finland found that alien predators have twice the impact as native predators on prey populations. Surprisingly, the research also showed that alien predators in mainland areas had a greater impact than in island environments, though the researchers say this finding may be biased by a large amount of data from Australia.
Predators prefer to eat stupid animals.
Predators such as jaguar and chimpanzees consistently target smaller-brained prey less capable of escape according to research published in the Royal Society Journal Biology Letters. The study, carried out by Dr Susanne Shultz, from the School of Biological Sciences at the University of Liverpool, found that predators avoid more intelligent prey such as monkeys which have exceptionally large brains and are more capable of escaping attacks.
How to save the world's big cats.
Big cats are some of Earth's largest and most threatened predators. Long persecuted as perceived threats to livestock and humans, hunted for their skins and purported medicinal values, and losing critical habitat to deforestation and conversion for agriculture, big cat populations have dwindled around the world for the past century. Recent years have seen the extinction of two sub-species of Indonesian tiger, the Caspian Tiger from western Central Asia, a sub-species of clouded leopard from Taiwan, and the Barbary lion from the wild in North Africa. Meanwhile, populations of the Iberian lynx, Asiatic cheetah and Amur leopard have fallen so low that they would be functionally extinct without current conservation efforts. Tiger populations have declined from more than 100,000 at the turn of the century to less than 6,000 today, while cheetah number are estimated at less than 15,000. Even lion populations have dropped: from over 100,000 one hundred years ago to probably less than 40,000 today.
The goal of re-introduction isn't simply to save a species; it is to restore the natural functions of wild places. When the predator-prey relationship comes back into balance, impacts ripple through the system. For example, when wolves returned to the Yellowstone region, they caused a cascade of events including a change in elk distribution, more wariness in moose, and a change in coyote densities. By contrast, where wolves and grizzly bears were lost, migratory birds including warblers and hummingbirds were less abundant because moose over-browsed vegetation used by these migrants.
"It is not just changes in climate or disease may alter our big remote wild landscapes, but so do the actions of conservationists and public agencies by restoring ecosystems to bring native carnivores back to where they once thrived." said Dr. Berger.
Berger's study, which looked at 19 areas including the Russian Far East, Greenland, Canada, and the U.S., demonstrated that caribou, elk, and moose are all affected by both the loss and return of their predators in ways that are important for conservation and ecosystem integrity.
These findings come at a time when, after more than $23 million was spent to re-establish wolves in the northern Rocky Mountains, the animals are to be down-listed from federal protection. The states of Wyoming and Idaho have already proposed plans that would allow for as much as 85 percent of these once-protected wolves to be killed. So even as the goal of re-instilling fear of predators in prey species has been successful, the question remains whether enough wolves will be left to maintain the larger goals of natural function and balance, according to Dr. Berger.
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