Birds are moving to higher altitudes due to fogged forests and rising temperatures: research

A 10-year study published by researchers at the Indian Institute of Science (IISc) analyzed population trends of insectivorous birds across an elevation gradient in the Western Ghats mountain range. The forests stretching along this biodiversity hotspot provide habitat for over 500 bird species. However, logging and climate change pose escalating threats. The study results reveal the interconnected impacts of habitat degradation from logging and rising temperatures on bird communities. Smaller understory species that forage in shrubs and on forest floors faced double jeopardy. As logging opened up canopies, drier and hotter microclimates developed from increased sunlight penetration. This caused a collapse in invertebrate prey populations from moisture loss in leaf litter and soils. Simultaneously, shrinking habitat meant fiercer competition with aggressive pioneers better adapted to disturbance.

Evidence of Upslope Migration of Birds

• Smaller insect-eating forest birds like flycatchers and warblers declined at lower elevations due to history of logging
• These species persisted at cooler higher elevations offering intact forests and food sources
• Clear upward elevational shifts observed from 750m to 1300m over past decade
• Allows smaller birds to escape rising temperatures in lowlands

Larger Birds More Vulnerable

• Larger birds like drongos, woodshrikes require more resources and territory
• Declined across logged habitats, stabilized only in high elevation old-growth forests
• Less nimble to migrate, at risk from extreme weather and warming

Dual Threats Confronting Montane Birds

• Climate change multiplying pressures already bearing from deforestation
• Intensifying existential threats to tropical montane birds
• Highlights urgent need for forest conservation

Intact Forests Critical for Resilience

• Maintaining forest cover along elevations facilitates climate adaptation
• Provides habitat heterogeneity for different species to shift upwards
• However, space running out with habitats disappearing near mountain peaks

Heeding Canary in the Coal Mine

• Birds mirror fragile state of wildlife populations globally
• Biodiversity declines directly affect ecosystem resilience capacities
• Radical forest conservation steps vital to maintain ecosystems regulating climate, disease, water security etc
• Shields against future catastrophe in increasingly resource-scarce world