Top-order predators is a broad phrase that we have intentionally chosen to describe carnivorous mammalian predators with a range of body sizes that occur at the upper end of the food chains of each continent. This defi nition is not limited by body mass or taxonomic clade, as it was intended to compare the actual or potential reintroduction of a diverse range of species from grey wolves, Canis lupus, to marsupial predators, such as Tasmanian devils, Sarcophilus harrisi.By their very nature, top-order predators are relatively rare in natural ecosystems-be they African lions, Panthera leo, preying upon the vast herds of wildebeest, Connochaetes taurinus, in the Serengeti; wolves preying upon the large elk, Cervus elaphus, herds of Yellowstone; or dingoes, Canis lupus dingo, preying upon the millions of kangaroos in the Simpson Desert. This inherent scarcity lends itself to diffi culty and insecurity in conservation efforts (Weber & Rabinowitz, 1996), as small declines in already small populations can set into motion unpredictable and uncontrollable stochastic forces as part of the small-population paradigm (Caughley, 1994).