Question

Barro Colorado Island was formed 85 years ago in central Panama when Gatun Lake was created as part of the Panama Canal. since that time 65 of 394 species of birds have disappeared from the island, 21 of them in the past 25 years. Discuss what mechanisms might cause extinctions of birds that can fly in an undisturbed area of tropical forest. Robinson (1999) discusses these changes.

Short answer

Factors like habitat fragmentation, genetic isolation, changes in resources, climate impact, and invasive species may cause bird extinctions, as discussed by Robinson (1999).

Step-by-step solution

Understand the Context

The problem discusses a specific geographical and historical context. Barro Colorado Island was formed 85 years ago in central Panama. It was created when Gatun Lake was formed, as a part of the Panama Canal construction. Since its formation, a significant number of bird species have become extinct.

Analyze the Data

The data indicates that out of 394 species of birds, 65 species have disappeared. Specifically, 21 species have become extinct in the past 25 years. This suggests a pattern or trend in the recent extinction of these species that may relate to specific causes.

Consider Potential Causes

Even though Barro Colorado Island is an undisturbed area of tropical forest, certain mechanisms can still lead to bird extinctions. Potential causes to consider include habitat fragmentation, changes in food resources, climate change, introduction of new species or diseases, and genetic isolation.

Explore Ecological and Biological Factors

Bird species in isolated environments can suffer due to limited gene pool diversity, increasing the likelihood of genetic disorders. Also, changes in the environment, even without direct human disturbance, can alter the availability of resources critical for survival. Invasive species and diseases can also disrupt the ecological balance.

Connect to Case Studies

Robinson (1999) provides insights into these extinction cases, discussing the possible changes and ecological dynamics influencing bird populations. Reviewing case studies and historical data such as Robinson's work can provide examples and precedents of similar extinction events to understand better the possible mechanisms at work.

Key concepts

Bird Extinction

Bird extinction on islands, such as Barro Colorado Island in Panama, provides a powerful example of how seemingly undisturbed areas can undergo significant biodiversity changes. While it may seem surprising that birds capable of flying can become extinct, several factors contribute to this phenomenon.

The primary drivers of bird extinction include:

• Limited resources: Islands often have finite resources that can lead to competition among species.
• Threats from invasive species: New species introduced to an area can become predators or competitors.
• Genetic bottlenecks: Smaller populations are more vulnerable to genetic disorders due to limited mating options.

These factors, compounded over decades, can negatively impact bird populations, leading to their eventual extinction. It's crucial to look at each factor closely to understand how it influences bird dynamics and survival.

Habitat Fragmentation

Habitat fragmentation is a critical concern in island ecology as it directly affects wildlife, including bird species. When an area is broken into smaller patches, the continuous habitat necessary for many species becomes disrupted.

On islands like Barro Colorado, fragmentation can lead to:

• Edge effects: The creation of more 'edges' decreases interior habitats, changing environmental conditions.
• Restricted movement: Birds may find it difficult to access different habitat patches, affecting their foraging and breeding.
• Isolation: Small habitat fragments can isolate populations, reducing genetic diversity and increasing vulnerability to extinction.

This phenomenon not only reduces the available space for birds but also affects their food redistributions and nesting sites, disrupting their natural life cycles.

Ecological Dynamics

Ecological dynamics refer to the complex interactions between organisms and their environment that change over time. In the context of islands like Barro Colorado, these dynamics are continually shaped by various factors and processes.

Key dynamics affecting bird populations include:

• Resource availability: Changes in resources such as food sources due to climatic or environmental changes can impact bird survival.
• Disease and invasive species: New diseases or predators can alter the ecological balance, threatening native bird species.
• Climate variations: Shifts in climate conditions can make existing habitats unsuitable for native species, leading to possible extinction.

These dynamics demonstrate the importance of understanding how interconnected and sensitive island ecosystems are, as slight changes can have cascading effects on species like birds.

Biodiversity Conservation

Biodiversity conservation on islands requires thoughtful strategies to prevent further extinctions and protect existing species. Planning is essential for maintaining the rich ecological tapestry of island habitats.

Here are some strategies aimed at conservation:

• Protected areas: Establish reserves to safeguard habitat from further fragmentation and human interference.
• Research and monitoring: Ongoing studies to observe changes in populations and identify potential threats early.
• Restoration efforts: Programs to rehabilitate degraded habitats and involve re-introduction of native species.
• Community involvement: Engaging local communities in conservation efforts to promote sustainable practices.

Effective conservation efforts can help preserve the unique biodiversity of islands, ensuring that ecosystems remain resilient to changes and threats in the future.