Guwahati: The slender-billed vulture, a critically endangered species primarily found in South and Southeast Asia, has seen drastic population declines due to habitat loss, poisoning, and changes in food availability. Arunachal Pradesh, with its unique blend of tropical forests and alpine vegetation, crisscrossed by numerous river systems, serves as one of the key habitats for this species in the Indian subcontinent and Southeast Asia.
Despite the region’s significance for vulture conservation, little research has been conducted on how climate variables might be impacting the bird’s survival and distribution, creating a gap in effective conservation planning.
However, a recent study conducted by researchers at Rajiv Gandhi University has provided valuable insights into how climate factors are influencing the distribution of the slender-billed vulture (Gyps tenuirostris) in Arunachal Pradesh.
Key Findings: Temperature, Rainfall, and Humidity
The study, which ran from 2016 to 2020, shows a clear relationship between the vulture’s distribution and climate variables, such as temperature, rainfall, and humidity. The researchers found that the vulture population is concentrated in areas with warmer temperatures and higher rainfall, while regions with high humidity appear to deter these scavengers.
Using extensive field surveys and Geographic Information System (GIS) analysis, the study found a positive correlation between vulture sightings and both temperature (rs = 0.61) and rainfall (rs = 0.29). Conversely, areas with higher humidity had a negative correlation with vulture presence (rs = -0.49).
The findings suggest that high temperatures help create thermal updrafts, which facilitate soaring and reduce the birds’ energy expenditure over long distances. Similarly, higher rainfall is linked to increased vegetation growth, which boosts the populations of herbivores that the vultures rely on for food. On the other hand, high humidity appears to limit the vulture’s ability to soar efficiently due to reduced thermal lift, restricting its ability to search for food effectively.
Temperature and Rainfall Patterns
Grids with the most frequent vulture sightings—G7, G8, and G9—recorded annual temperatures between 23.78°C and 24.32°C, some of the highest in the study area. Rainfall in these regions ranged from 220 to 285 mm annually, and relative humidity was relatively low, between 67.55% and 75.18%. These conditions align with the vulture’s preferences.
In contrast, areas with high rainfall but also higher humidity—regions like East Siang and Lohit—showed no vulture sightings. This supports the theory that high humidity may impede the bird’s ability to thermoregulate and fly effectively.
Conservation Implications
The findings underscore the importance of climate-informed conservation strategies for the slender-billed vulture. The study suggests that areas like East Siang, Lower Dibang Valley, Lohit, and Namsai, where vulture sightings were concentrated, should be prioritized for conservation, especially as climate change is expected to alter regional weather patterns.
As temperatures rise and rainfall patterns shift due to climate change, the vulture’s habitat could shrink further, posing a significant threat to its population. The researchers emphasize that monitoring climate variables, alongside other conservation efforts, is critical for protecting these vultures.
For example, conservationists could focus on preserving areas with lower humidity and ample thermal updrafts, which support the vulture’s foraging behavior. Ongoing monitoring would also help track shifts in the species’ distribution and provide data for adapting conservation strategies as the climate continues to change.
Looking Ahead
This study offers crucial insights into how climate conditions influence the slender-billed vulture’s habitat preferences in Arunachal Pradesh. However, the researchers note that further studies are needed to explore other factors, including human activity and food availability, that may also affect vulture survival. By considering a broader range of ecological and anthropogenic influences, conservationists can develop a more holistic approach to safeguarding this critically endangered species.