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The IUCN Red List of Threatened Species Red List Criteria: Criterion A.

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Presentation on theme: "The IUCN Red List of Threatened Species Red List Criteria: Criterion A."— Presentation transcript:

1 The IUCN Red List of Threatened Species Red List Criteria: Criterion A

2 Criterion A Time Population Size Past, present or future population reduction

3 Criterion A To use criterion A, we first need to know: What is the generation length? Or is it likely that a three generation time period is less than 10 years? Time Population Size 3 generations or 10 years (whichever is the longer)

4 Criterion A Based on any of four criteria: * Up to a maximum of 100 years into the future Timing of ReductionReduction Conditions PastFuture Causes Understood Causes Stopped Effects are reversible A1 A2 A3 * A4 *

5 Criterion A

6 Example: a whale Generation length ~ 31 years Population decline 70-90% over past 3 generations. Populations appear to be recovering. Population declines caused by commercial whaling: o o Cause and effects of decline is fully understood o o Commercial whaling has stopped o o Pop decline appears to be reversible Percentage decline based on: o o Whale sightings and observations o o Stock monitoring surveys and reports o o Whaling statistics and records Given uncertainty in the decline and current stability and population recovery, is listed as EN. EN A1abd CR/EN A1 CR/EN A1d CR/EN A1b CR/EN A1a

7 Example: a tree Generation length unknown; ~ 50 years in similar species Endemic to dry forest, which have been intensively cut for agriculture over last century. Today only highly fragmented forest patches remain, and suffer: o o Intense predation from deer and cattle o o Uncontrolled fires Estimated 95% habitat loss over past 150 years: given population densities & distribution, suspected population decline of at least 50%. Habitat loss ongoing. Regeneration close to zero due to intensive grazing; seeds also consumed by butterfly larvae – suspected population decline of up to 80% over next 100 years. Population decline rate based on: o o Massive habitat loss o o Introduced predators EN A2 CR/EN A3 A2+3c A2+3e EN A2+3ce

8 Criterion A Near Threatened (NT) example: Should be close to meeting the VU thresholds or possibly meet some of the subcriteria Population has declined by 20-25% in the last three generations Causes of the decline are not understood and appear to be ongoing (i.e. the population is still declining) NT, nearly meeting VU A2 Population has declined by 40% in the last three generations Causes of decline are understood, the causes have stopped, and the decline is reversible. NT, nearly meeting VU A1 Population has declined by 40% in the last three generations Causes of decline are understood, the causes have stopped, and the decline is reversible. NT, nearly meeting VU A1

9 Criterion A Criterion A4 past & future: shifting time window 10 years / 3 generations Present 10 years / 3 generations

10 Criterion A Past census data gathered every 2 yrs Reduction rate over next 30 yrs Estimated future populations YearPopulation size YearPopulation size ,00033%20026, ,00038%20045, ,00043%20065, ,00047%20084, ,00051%20104, ,00054%20124, ,94056%20144, ,82057%20164, ,64058%20184, ,40057%20204, ,10056%20224, ,74054%20244, ,32052%20264, ,84049%20284, ,30045%20304, ,70040%20324,000 Present Reliable data available If a moving-window reduction cannot be calculated over the full time series: Criterion A4 past & future: shifting time window Most confident 10 year / 3 generation time period

11 Criterion A 3 generations? 10 years? To use criterion A, an estimate of the generation length is needed Population reduction may be a one-off event Or it may be ongoing Points to remember:

12 Criterion A Criterion A1 uses higher thresholds than A2, A3 and A4 Points to remember:

13 Criterion A A3 = projected FUTURE reduction so cannot be based on direct observation (A3a) Points to remember:

14 Criterion A Consider the pattern of population reduction Points to remember:

15 Criterion A Refer to User Guidelines and CriterionA.xls for information and advice


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