Using IUCN criteria to perform rapid assessments of at-risk taxa

Table 1 The IUCN Red List criteria thresholds

Thresholds for IUCN Red List criteria
Criteria			Critically Endangered	Endangered	Vulnerable	No thresholds met
(A)	Population size reduction		≥80% population reduction over the longer of 10 years or 3 generations
(B)	Geographic range size	1. EOO	<100 km²	<5000 km²	<20,000 km²	>20,000 km²
		2. AOO	<10 km²	<500 km²	<2000 km²	>2000 km²
(C)	Small population size and decline		<250 Mature individuals
(D)	Very small populations		<50 Mature individuals

The Critically Endangered thresholds for all criteria were used for flagging species that would face increased extinction risk following further loss (referred to as serious and irreversible impacts (SAII)). While the geographic range criteria thresholds, extent of occurrence (EOO) and area of occupancy (AOO), for each threat category (Critically Endangered – Vulnerable) were used to assess non-listed species across Australia