Climate Change Threatens Nilgiri Wood Pigeon Habitat

Recent research marks the severe impact of climate change on the Nilgiri Wood Pigeon (Columba elphinstonii), an endemic bird of the Western Ghats. The study reveals that by the end of this century, the species’ suitable habitat could shrink drastically to a few isolated pockets. This poses a grave threat to the survival of the pigeon and other specialised montane species in this biodiversity hotspot.

Habitat and Distribution

The Nilgiri Wood Pigeon inhabits high-elevation wet evergreen and moist deciduous forests. Its core range includes the Nilgiris and Anamalai Hills in Tamil Nadu and Kerala. Smaller populations exist in the Biligirirangan Hills, Nandi Hills, and parts of northern Maharashtra. These sky islands are characterised by unique ecosystems with high endemism. The pigeon depends on intact forest canopies and has a limited elevational range, making it highly specialised and vulnerable.

Climate Change Impact and Modelling

Using MaxEnt, a machine-learning tool, researchers modelled habitat suitability based on 9,757 citizen-science bird sighting records and nine bioclimatic variables. The model predicts an initial increase in suitable habitat at lower montane elevations between 2021 and 2040. However, from 2081 to 2100, a sharp decline is expected. The species shows a non-linear response to warming – moderate temperature rise may temporarily expand its niche, but ongoing warming will contract its habitat severely.

Conservation Challenges and Recommendations

Despite being down-listed to Least Concern by the IUCN, the Nilgiri Wood Pigeon’s population estimates lack systematic ground verification. The study stresses the need for climate-resilient conservation plans targeting high-altitude forests. Researchers urge comprehensive ecological surveys covering population size, breeding habits, and habitat use. Proactive measures should anticipate habitat shifts rather than respond to population declines post facto.

Significance for Western Ghats Biodiversity

The Nilgiri Wood Pigeon is among 16 bird species in the Western Ghats’ mid and high elevations vulnerable to climate change. Protecting this species can serve as a flagship for conserving the region’s montane biodiversity. The study underlines the urgency of integrating climate projections with conservation strategies to safeguard these fragile ecosystems and their endemic species.

Topics for Prelims:

Nilgiri Wood Pigeon

1. Endemic to Western Ghats high-elevation forests.
2. Prefers wet evergreen and moist deciduous forests.
3. Dependent on undisturbed forest canopy.
4. Population estimates lack systematic surveys.
5. Faces habitat contraction due to climate change.

Western Ghats Ecosystem

1. Recognised biodiversity hotspot in India.
2. Contains sky islands with unique montane habitats.
3. High levels of endemism and ecological specialisation.
4. Threatened by deforestation, agriculture, and climate change.
5. Supports specialised species like Nilgiri Wood Pigeon.

MaxEnt Habitat Modelling

1. Machine-learning method for species distribution modelling.
2. Uses occurrence records and environmental variables.
3. Predicts habitat suitability under climate scenarios.
4. Shows non-linear species responses to warming.
5. Informs conservation planning and risk assessment.

Questions for UPSC:

1. Critically discuss the impact of climate change on endemic species in biodiversity hotspots like the Western Ghats.
2. Examine the role of citizen science projects such as eBird in enhancing biodiversity conservation and research.
3. Analyse the importance of machine-learning tools like MaxEnt in ecological modelling and conservation decision-making.
4. Point out the challenges in assessing conservation status of elusive species and suggest measures to improve accuracy in such assessments.

Answer Hints:

1. Critically discuss the impact of climate change on endemic species in biodiversity hotspots like the Western Ghats.

1. Endemic species have restricted ranges and specialised habitat requirements, making them highly vulnerable to environmental changes.
2. Climate change causes habitat shifts, often pushing species to higher elevations or shrinking suitable habitat (“habitat compression”).
3. In the Western Ghats, montane species like the Nilgiri Wood Pigeon face range contractions and fragmentation due to warming and altered precipitation.
4. Loss of habitat connectivity increases isolation of populations, raising extinction risks and reducing genetic diversity.
5. Climate change interacts with anthropogenic pressures such as deforestation and land-use change, exacerbating threats to endemic species.
6. Urgent need for climate-resilient conservation strategies to maintain ecosystem integrity and species survival in biodiversity hotspots.

2. Examine the role of citizen science projects such as eBird in enhancing biodiversity conservation and research.

1. Citizen science projects collect extensive species occurrence data over large geographic and temporal scales at low cost.
2. Platforms like eBird enable real-time data submission, increasing data volume and coverage, especially in remote or under-surveyed areas.
3. Such data support species distribution modelling, trend analysis, and identification of critical habitats.
4. Citizen involvement raises public awareness and engagement in biodiversity conservation efforts.
5. Data quality can vary but can be improved through validation protocols and expert review.
6. Citizen science complements traditional surveys, filling data gaps and informing conservation policy and management.

3. Analyse the importance of machine-learning tools like MaxEnt in ecological modelling and conservation decision-making.

1. MaxEnt uses presence-only data and environmental variables to predict species habitat suitability with high accuracy.
2. It handles complex, non-linear relationships between species occurrence and environmental factors.
3. Enables projection of future habitat changes under climate scenarios, facilitating anticipatory conservation planning.
4. Supports identification of priority areas for protection and restoration based on habitat suitability maps.
5. Useful for elusive or rare species where absence data are unreliable or unavailable.
6. Machine-learning models increase efficiency and objectivity in ecological assessments and risk evaluations.

4. Point out the challenges in assessing conservation status of elusive species and suggest measures to improve accuracy in such assessments.

1. Elusive species often have patchy distributions and low detectability, leading to incomplete or biased population data.
2. Lack of systematic ground surveys causes uncertainty in population size and trend estimates.
3. Current conservation status may not reflect emerging threats like climate change and habitat fragmentation.
4. Integration of ecological modelling with field-based demographic studies is essential for accurate assessments.
5. Regular, long-term monitoring and standardized survey protocols improve data reliability and trend detection.
6. Use of technology (camera traps, eDNA, acoustic monitoring) can enhance detection of elusive species.