TABLE 5.1 Factors contributing to level of concern for species transformed.

	Factor Contributing to Concern
Animal	Number of Citations1	Ability to Become Feral2	Likelihood of Escape Captivity3	Mobility4	Community Disruptions Reported5	Level of Concern6
Insects8	1804	High	High	High	Many
Fish7	186	High	High	High	Many
Mice/ Rats	53	High	High	High	Many
Cat	160	High	High	Moderate	Many
Pig	155	High	Moderate	Low	Many
Goat	88	High	Moderate	Moderate	Some
Horse	93	High	Moderate	High	Few
Rabbit	8	High	Moderate	Moderate	Few
Mink	16	High	High	Moderate	None
Dog	11	Moderate	Moderate	Moderate	Few
Chicken	11	Low	Moderate	Moderate	None
Sheep	27	Low	Low	Low	Few
Cattle	16	Low	Low	Low	None
1 Number of scientific papers dealing with feral animals of this species. 2 Based on number of feral populations reported. 3 Based on ability of organism to evade confinement measures by flying, digging, swimming, or jumping ability for any of the life stages. 4 Relative dispersal distance by walking, running, flying, swimming, or hitchhiking in trucks, trains, boats, etc. 5 Based on worldwide citations reporting community damage and extent of damage. 6 A ranking based on the four contributing factors. 7 Did not include shellfish, some of which (such as zebra mussel and asiatic clam) have proven highly invasive. 8Limited to gypsy moth and Africanized honeybee.

The stability and resilience of the receiving community is another factor that influences whether transitory or long-term harm results from the introduction of GE animals. Colonization by GE animals might result in local displacement of a conspecific population, which could have a disruptive effect on other species in a community, for example, by releasing competing species from resource competition or prey species from predation (Kapuscinski and Hallerman, 1990); additionally, the survival of predatory species that depend on the eliminated species could be threatened. This concern is best exemplified by the classic experiment of Paine (1966) in the rocky intertidal zone. By experimentally removing the top predator, a starfish (Piaster sp.), the number of species in the plot was reduced from 15 to eight. Another example is the impact of pigs on plant species diversity reported by Hone (2002). Ground rooting of feral pigs in Namadgi National Park, Australia, decreased the number of plant