Megafauna are large animals of any particular region or time. Generally, they are defined as animals that weigh over 500 kg to 1 tonne, i.e., any animal larger than the largest widespread domestic animal, the domestic bull. Some authors use much lower thresholds, even as low as 50 kg (making humans a megafauna species), but they are not widely accepted. The term is also used to refer to particular groups of large animals, both to extant species and, more often, those that have become extinct in geologically recent times.
Megafauna animals are generally K-strategists, with great longevity, slow population growth rates, low death rates, and few or no natural predators capable of killing adults. These characteristics make megafauna highly vulnerable to human exploitation. Many species of megafauna have become extinct within the last million years, and, although some biologists dispute it, human hunting is often cited as the cause.
The second is that climate changes, most notably increases in average temperature, caused them to die out. Research published in 2006 on the wooly mammoth, for example, indicates that this was the probable cause of their extinction, as opposed to excessive hunting by humans. *
Charismatic megafauna often garner a disproportionate level of public concern. Environmental activists are aware of this effect and use the extra leverage provided by a charismatic species to achieve more subtle and far-reaching goals. By directing public attention to the plight of the Giant Panda, for example, the environmental movement can raise support not just for the protection of the panda, but for the entire ecosystem on which it depends.
See also: Australian megafauna
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