Critically Endangered

Definition and Criteria

A species is classified as "Critically Endangered" (CR) when it faces an extremely high risk of extinction in the wild. This classification is part of the IUCN Red List of Threatened Species, which is a comprehensive inventory of the global conservation status of biological species. The criteria for this classification are stringent and involve quantitative thresholds related to population size, rate of decline, geographic range, and other factors.

Criteria for Classification

The IUCN Red List uses five quantitative criteria to evaluate the extinction risk of a species. A species is listed as Critically Endangered when it meets any of the following criteria:

A. Population Reduction

1. An observed, estimated, inferred, or suspected population size reduction of ≥90% over the last 10 years or three generations, whichever is longer, where the causes of the reduction are clearly reversible and understood. 2. A population size reduction of ≥80% over the last 10 years or three generations, where the reduction or its causes may not be reversible or understood.

B. Geographic Range

1. Extent of occurrence estimated to be less than 100 km², or area of occupancy estimated to be less than 10 km², and estimates indicating:

  - Severely fragmented or known to exist at only a single location.
  - Continuing decline observed, inferred, or projected in the extent of occurrence, area of occupancy, area/extent/quality of habitat, number of locations or subpopulations, or number of mature individuals.

C. Small Population Size and Decline

1. Population size estimated to number fewer than 250 mature individuals and either:

  - An estimated continuing decline of at least 25% within three years or one generation, whichever is longer.
  - A continuing decline, observed, projected, or inferred in numbers of mature individuals and at least 90% of mature individuals in one subpopulation, or no more than 50 mature individuals in any one subpopulation.

D. Very Small or Restricted Population

1. Population size estimated to number fewer than 50 mature individuals. 2. Population size estimated to number fewer than 250 mature individuals, with a continuing decline observed, projected, or inferred.

E. Quantitative Analysis

1. Quantitative analysis showing the probability of extinction in the wild is at least 50% within 10 years or three generations, whichever is longer.

Causes of Critical Endangerment

The primary causes of species becoming critically endangered are multifaceted and often interrelated. They include habitat destruction, climate change, overexploitation, invasive species, and pollution.

Habitat Destruction

Habitat destruction is one of the leading causes of species becoming critically endangered. Activities such as deforestation, urbanization, and agricultural expansion lead to the loss of natural habitats. For example, the Sumatran Orangutan is critically endangered due to extensive deforestation in Indonesia.

Climate Change

Climate change has far-reaching impacts on biodiversity. Changes in temperature and precipitation patterns can alter habitats and the availability of resources, leading to population declines. The Polar Bear is a notable example, as melting ice caps reduce its hunting grounds.

Overexploitation

Overexploitation refers to the unsustainable use of species for commercial, recreational, or subsistence purposes. This includes hunting, fishing, and logging. The Vaquita, a small porpoise found in the Gulf of California, is critically endangered due to bycatch in illegal gillnets used for fishing the totoaba fish.

Invasive Species

Invasive species can outcompete, prey on, or bring diseases to native species, leading to declines. The introduction of the brown tree snake to Guam has led to the near extinction of several bird species on the island.

Pollution

Pollution, including chemical, plastic, and noise pollution, can have detrimental effects on species. For instance, the Yangtze River Dolphin has been critically endangered due to industrial pollution and heavy boat traffic in its habitat.

Conservation Efforts

Conservation efforts for critically endangered species involve a combination of in-situ and ex-situ strategies, legal protections, and community engagement.

In-Situ Conservation

In-situ conservation involves protecting species in their natural habitats. This includes establishing protected areas, habitat restoration, and implementing sustainable land-use practices. The establishment of the Yellowstone National Park has been crucial for the conservation of species like the Gray Wolf.

Ex-Situ Conservation

Ex-situ conservation involves the preservation of species outside their natural habitats, such as in zoos, botanical gardens, and seed banks. Captive breeding programs have been instrumental in the recovery of species like the California Condor.

Legal Protections

Legal protections at national and international levels are critical for the conservation of critically endangered species. The CITES regulates international trade in endangered species to ensure it does not threaten their survival.

Community Engagement

Engaging local communities in conservation efforts is essential for the success of conservation programs. Community-based conservation projects empower local people to protect wildlife and their habitats while providing economic benefits.

Case Studies

Sumatran Rhino

The Sumatran Rhino is one of the most critically endangered mammals, with fewer than 80 individuals remaining in the wild. Habitat loss and poaching have driven the species to the brink of extinction. Conservation efforts include habitat protection, anti-poaching measures, and captive breeding programs.

Javan Rhino

The Javan Rhino is another critically endangered species, with only one known population in Ujung Kulon National Park in Indonesia. Conservation efforts focus on habitat protection and monitoring to prevent poaching and habitat encroachment.

Hawksbill Turtle

The Hawksbill Turtle is critically endangered due to illegal trade in its shell, habitat loss, and climate change. Conservation efforts include protecting nesting beaches, regulating trade, and raising awareness about the species' plight.

Sumatran Rhino in a lush forest habitat.

Sumatran Rhino in a lush forest habitat.

Challenges and Future Directions

Conservation of critically endangered species faces numerous challenges, including limited funding, political instability, and the complexity of ecological systems. Future directions in conservation include:

Integrating Technology

The use of technology, such as drones, satellite tracking, and genetic analysis, can enhance monitoring and protection efforts. For example, drones are used to monitor poaching activities in real-time.

Climate Change Mitigation

Addressing climate change through mitigation and adaptation strategies is crucial for the long-term survival of many species. This includes reducing greenhouse gas emissions and implementing habitat corridors to facilitate species migration.

Policy and Legislation

Strengthening and enforcing environmental policies and legislation at local, national, and international levels is essential. This includes creating new protected areas and enhancing existing ones.

Public Awareness and Education

Raising public awareness and education about the importance of biodiversity and the threats faced by critically endangered species can garner support for conservation efforts. Educational programs and media campaigns play a vital role in this regard.

See Also

• Endangered Species
• Biodiversity
• Conservation Biology