Anthropogenic changes in Himalayas threatens species survival: IISc study

BENGALURU: A team of researchers from the Indian Institute of Science (IISc), Bengaluru, have found that the avian species in the Himalayan regions are under threat due to habitat degradation. They also noted that anthropogenic changes were threatening the survival of the avian species in the Himalayas. This study was conducted in the Eastern Himalayas' Eaglenest Wildlife Sanctuary in Arunachanal Pradesh for a period of 10 years and it was concluded that the insectivorous birds found in the understorey regions (below the canopies) were under threat. The researchers from the Centre for Ecological Sciences (CES), IISc, studied how the changes in the forest microclimates influenced the survival of the wild bird population. The study titled- Microclimatic niche shifts predict long-term survival and body mass declines in a warmer and more degraded world, was done from 2011-2021. On November 11, it was published on the British Ecological Society Journal under the open access publishing success: a guide for authors category. The researchers in the report noted that while tropical species worldwide are exposed to and respond to the synergistic impacts of multiple global change drivers, such as climate change and habitat degradation. The underlying mechanisms shaping species' demographic and phenotypic responses to anthropogenic changes remained poorly understood. They used a mark-recapture data set. They tagged birds with lightweight aluminum rings and revisited the same sites annually to track their survival and changes in body mass. They paired the dataset with temperature-humidity loggers placed in both primary and logged forests, to estimate how these insectivorous birds adapt to microclimatic changes. Using these long-term data sets, we can better understand why some species survive after logging while others decline strongly, said Akshay Bharadwaj, co-author of the study. The teams noted that the logged forests were consistently hotter and drier during the day and colder at night in comparison to the primary forests exposing birds to stressful fluctuations due to loss of forest canopy. Scientists pointed that these could intensify with climate change in the Eastern Himalayas where bird species are thermal specialists uniquely adapted to stable climates. Species that can still find microclimates in logged forests similar to their original forest homes are surviving after selective logging. It is those which cannot match their old conditions that face steep declines, Bharadwaj said. Based on the findings, the researchers suggested that conservation strategies should prioritize preserving primary forest across elevational gradients. In degraded areas, we can consider microclimatic remediation, such as creating shade covers or supplementing water sources to mimic original microhabitats to support vulnerable species. The impacts of forest degradation will impact food chains that are part of larger ecosystem processes. A drop in the number of insectivorous birds can lead to an increase in insect numbers, which in turn can affect ecological stability, the report pointed. As the climate warms, the persistence of microhabitats will be crucial for many species to remain resilient to climate impacts, said co-author and Assistant Professor at CES, Umesh Srinivasan.