majority of documented global extinctions attributed mainly 
to invasive alien species occurring on islands, local 
extinctions account for 9 per cent of documented impacts 
of invasive alien species on islands, in contrast to 4 per 
cent on mainlands (well established) {4.3.1.1}. For 
example, Boiga irregularis (brown tree snake) caused the 
global extinction of Myiagra freycineti (Guam flycatcher) 
and local extinction or serious population reduction for 
many other resident bird species in Guam (well 
established) {4.3.1}. Islands are also vulnerable to climate 
change, which can increase the rate of establishment and 
spread of many invasive alien species (well established)
{Box 2.5}. Many invasive alien species on islands only 
occupy a small portion of their predicted range and are 
likely to expand further (established but incomplete) {Box 
2.5}. The number of alien plants exceeds the total number 
of native plants on more than one quarter of islands (well 
established) {Box 2.5}. Invasive alien species have been 
reported in areas protected for nature conservation, some 
remote areas (e.g., high mountains), and also in tundra and 
deserts, which emphasizes that these areas, despite being 
protected for nature conservation or remote, are also 
vulnerable to the negative impacts of invasive alien species 
(well established) {Box 2.4, 4.3.1.2, 4.3.2.1}. Fifty-three 
invasive alien species have caused the local extinctions of 
240 native species in protected areas globally (established 
but incomplete) {4.3.1.2}. The invasive alien Rattus rattus 
(black rat) has been documented as the only cause of the 
global extinction of Nesoryzomys darwini and 
Nesoryzomys indefessus (rice rats), which were endemic to 
the protected areas of the Galapagos Islands (well 
established) {4.3.1}.
SUMMARY FOR POLICYMAKERS
19SUMMARY FOR POLICYMAKERS
BACKGROUND
Figure SPM 2 Examples of invasive alien species with a negative impact on nature (green), 
and, in some cases, nature's contributions to people (yellow) and/or good 
quality of life (teal). 