Understanding Changes in Conservation Status of Indonesian Bird Species: The IUCN Red List

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*Heri Tarmizi

This essay explores the aspects and parameters involved in changes to the conservation status of Indonesian bird species as assessed by the IUCN Red List, including a focus on the Aceh Bulbul (Pycnonotus snouckaerti).

Indonesia is home to a remarkable diversity of bird species, many of which are endemic to the archipelago. The International Union for Conservation of Nature (IUCN) Red List of Threatened Species assesses the conservation status of these birds, providing critical information for their protection. The IUCN Species Information Service (SIS) manages the data on these species, evaluating various aspects and parameters that influence changes in their conservation status. This essay explores the aspects and parameters involved in changes to the conservation status of Indonesian bird species as assessed by the IUCN Red List, including a focus on the Aceh Bulbul (Pycnonotus snouckaerti).

1. Overview of the IUCN Red List

The IUCN Red List categorizes species into nine groups based on their risk of extinction: Not Evaluated (NE), Data Deficient (DD), Least Concern (LC), Near Threatened (NT), Vulnerable (VU), Endangered (EN), Critically Endangered (CR), Extinct in the Wild (EW), and Extinct (EX). These categories are determined using quantitative criteria that assess population trends, geographic range, and the severity of threats.

2. Criteria for Assessing Conservation Status

The IUCN Red List assessments for Indonesian birds, as with all species, are based on five main criteria:

a. Population Reduction (Criterion A)

This criterion evaluates the reduction in population size over a specific period. For example, a significant decline in the population of the Javan Hawk-Eagle (Nisaetus bartelsi) due to habitat loss and illegal trade may qualify it for a higher risk category.

b. Geographic Range (Criterion B)

This criterion assesses the extent of occurrence (EOO) and area of occupancy (AOO). For instance, the Bali Starling (Leucopsar rothschildi) has a very restricted geographic range, making it highly susceptible to threats such as habitat destruction and poaching.

c. Small Population Size and Decline (Criterion C)

This criterion considers the number of mature individuals and the rate of decline. Species with small and declining populations, like the Sumatran Ground-cuckoo (Carpococcyx viridis), face a higher risk of extinction.

d. Very Small or Restricted Population (Criterion D)

This criterion applies to species with very small population sizes or limited distributions. The Black-winged Myna (Acridotheres melanopterus) is an example, with fewer than 1,000 mature individuals left in the wild due to illegal pet trade.

e. Quantitative Analysis (Criterion E)

This criterion involves risk analyses that estimate the probability of extinction over a given period. Population viability analyses (PVA) for species like the Yellow-crested Cockatoo (Cacatua sulphurea) help assess their future survival prospects under current and projected threats.

3. Aspects Influencing Changes in Conservation Status

Several factors influence the conservation status of Indonesian bird species:

a. Habitat Loss and Degradation

Habitat loss and degradation are primary threats. Deforestation for agriculture, logging, and infrastructure development reduces available habitats. The Javan Hawk-Eagle, for example, is critically affected by the loss of primary forest habitats on Java.

b. Climate Change

Climate change alters habitats and affects bird species differently. Changes in temperature and precipitation patterns can disrupt breeding and migratory behaviors. For instance, the Wallace’s Standardwing (Semioptera wallacii) may face habitat shifts due to changing climate conditions in the Maluku Islands.

c. Invasive Species

Invasive species can outcompete native birds for resources or directly predate them. The introduction of the Javan Myna (Acridotheres javanicus) has impacted native bird populations by competing for food and nesting sites.

d. Overexploitation

Overexploitation through hunting and trapping for the pet trade severely impacts bird populations. The illegal trade of the Black-winged Myna has pushed it towards extinction in the wild.

e. Pollution

Pollution, including pesticide use and water pollution, adversely affects bird populations. Pesticides can poison birds directly or reduce insect prey availability, impacting species like the Java Sparrow (Lonchura oryzivora).

f. Disease

Emerging infectious diseases pose significant threats. Avian influenza and other diseases can cause high mortality rates and contribute to population declines, affecting various bird species across Indonesia.

4. Parameters for Evaluating Conservation Status Changes

To evaluate changes in the conservation status of Indonesian bird species, the IUCN considers several parameters:

a. Population Trends

Long-term monitoring of population trends is crucial. Reliable data on population sizes and trends help determine if a species is experiencing declines, stability, or increases. For instance, ongoing surveys of the Bali Starling population provide essential data for its conservation status assessment.

b. Habitat Trends

Changes in habitat quality and extent are assessed through satellite imagery, land-use data, and field surveys. Habitat loss and fragmentation are key indicators. For example, deforestation rates in Sumatra impact the Sumatran Ground-cuckoo’s habitat.

c. Threats Assessment

Identifying and evaluating the severity and scope of threats is vital. Threats are categorized and their impacts are quantified. This information helps understand the drivers of population changes and informs conservation actions.

d. Conservation Actions

The effectiveness of conservation measures is assessed. Protected areas, habitat restoration, and species-specific interventions can stabilize or improve the status of bird species. Successful breeding programs and habitat protection efforts have been crucial for the Bali Starling.

e. Climate Change Projections

Climate models and projections predict future changes in habitat suitability and species distributions. These projections help assess the long-term viability of species under changing climatic conditions, informing adaptive management strategies .

5. Case Studies of Conservation Status Changes in Indonesian Birds

a. Javan Hawk-Eagle (Nisaetus bartelsi)

The Javan Hawk-Eagle is endemic to Java and has experienced significant population declines due to habitat loss and fragmentation. Conservation efforts, including habitat protection and captive breeding programs, have been implemented. Despite these efforts, the species remains Critically Endangered due to ongoing habitat destruction and illegal trade.

b. Bali Starling (Leucopsar rothschildi)

The Bali Starling, also known as the Bali Mynah, has been on the brink of extinction due to habitat loss and illegal poaching for the pet trade. Intensive conservation efforts, including captive breeding and reintroduction programs, have led to a slow recovery. However, the species remains Critically Endangered, with wild populations still extremely small and vulnerable.

c. Black-winged Myna (Acridotheres melanopterus)

The Black-winged Myna has suffered severe declines due to illegal capture of the pet trade. Conservation actions, such as strict enforcement of trade regulations and captive breeding, are being pursued. The species is listed as Critically Endangered, with urgent measures needed to prevent its extinction in the wild.

d. Aceh Bulbul (Pycnonotus snouckaerti)

The Aceh Bulbul, endemic to the northern region of Sumatra, is currently assessed as Vulnerable due to its restricted range and ongoing habitat loss. The species is primarily threatened by deforestation for agriculture and logging activities. Conservation efforts focus on habitat protection and management within the Aceh province. Continued monitoring and protection of its habitat are crucial to prevent further declines.

Conclusion

The IUCN Red List is a crucial tool for assessing and monitoring the conservation status of bird species, including those in Indonesia. Changes in conservation status are influenced by factors such as habitat loss, climate change, invasive species, overexploitation, pollution, and disease. The IUCN uses quantitative criteria and various parameters to evaluate these changes, ensuring comprehensive and accurate assessments. Understanding these factors is essential for implementing effective conservation strategies and ensuring the survival of Indonesian bird species amidst ongoing environmental challenges.

References

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