CCMB-NCF study maps India’s first hornbill genomes, reveals impact of ancient climate change

A CCMB-NCF study has mapped the genomes of four Asian hornbill species for the first time in India. The research reveals that ancient climate changes caused population declines, reducing genetic diversity and increasing the birds’ vulnerability to modern environmental threats.

Hyderabad: Scientists from Hyderabad and Karnataka have unlocked the genetic codes of four Asian hornbill species, revealing that the majestic birds were hit by prehistoric climate shocks, which laid the seeds of their own dwindling numbers long before humans began destroying their habitats.

For the first time in the country, the researchers from Hyderabad’s Centre for Cellular and Molecular Biology (CSIR-CCMB) and Nature Conservation Foundation (NCF India), Mysore, have mapped the complete genetic blueprints of four iconic Asian hornbill species, including Great Hornbill, Wreathed Hornbill, Malabar Pied Hornbill, and Rufous-necked Hornbill.

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The genomic code of these birds, published in the preprint journal bioRxiv, sheds new light on the birds’ struggle to survive. Until now, it was widely assumed that hornbill populations were thriving until humans started hunting.

However, a genomic study by CCMB-NCF researchers has discovered that hornbills were already nursing deep, invisible wounds from ancient history.

During the Pleistocene era, tens of thousands of years ago, Earth experienced unpredictable climate swings due to ice ages, which reduced tropical rainforests where hornbills lived.

The new genomic data from CCMB-NCF reveals that all four hornbill species suffered drastic population crashes during the prehistoric ice age, plummeting their numbers and reducing their gene pools even before the foundations of the modern cities were laid.

Known as the ‘Farmers of the Forest’, hornbills feast on wild fruits and fly long distances, dropping seeds that in turn regenerate canopy trees and keep rainforests alive. But as a result of their narrowing gene pool, these vital seed-dispersers are losing genetic variation, making them vulnerable to diseases, heatwaves, or environmental shifts, a major reason why they are on the IUCN threatened red list.

Since ancient climate change had already reduced hornbill populations, modern hornbill populations are already dwindling. The limited genetic material pool is causing inbreeding, weaker offspring, higher disease susceptibility, and eventual local extinction.

Prior to the CCMB-NCF study, scientists were trying to save these birds largely in the dark. Out of 32 Asian hornbill species, almost none had high-quality, fully mapped whole-genome references created in India. By building these comprehensive genome maps, the researchers have now effectively created a genetic baseline for hornbills in the entire country.