Table 3.

Comparison of harmful environmental impact information between island and mainland landmasses. Harmful impacts are those characterized as impact severities that range from being responsible for population declines to the irreversible extinction of native species (i.e., include Moderate (MO), Major (MR) and Massive (MV) categories). There was no difference in the proportion of impact studies that had evidence of harmful impacts between island and mainland landmasses. Information was based on all environmental impact evidence, i.e., some species were included more than once.

	Island	Mainland
Total number of species	53	94
Total number of impact studies	154	384
Impact severity frequency: MC, MN, MO, MR, MV	23, 78, 46, 7, 0	54, 200, 110, 20, 0
No. harmful impacts (percentage of total)	53 (34%)	130 (34%)
Mean number of studies per species (sd)	3.28 ($\sigma$ = 4.00)	4.59 ($\sigma$ = 7.40)
Median number of studies per species	1	3