Guwahati: Somewhere in the forests and grasslands of Northeast India, a small and little-known rodent may still be surviving, even though it has not been confirmed in the wild for 76 years.
The Manipur bush rat (Hadromys humei) is an endangered rodent found only in Northeast India. A new review now calls for targeted surveys to determine whether the species is still surviving and where it might be found.
Published in the Journal of Lost Species, the study highlights how little is known about the Manipur bush rat. Its last confirmed record came from field investigations in Manipur in 1945. Since then, no confirmed records of the species have been found in the wild.
The study was authored by Sourav Gupta, PhD Research Scholar at Assam University, Diphu Campus, and Senior Wildlife Biologist at Aaranyak; Dr Ramie H. Begum, Associate Professor and Head, Department of Life Science and Bioinformatics, Assam University, Diphu Campus; Dr. M. Firoz Ahmed, Scientist F, Director and Head, Tiger and Herpetofauna Research and Conservation Division, Aaranyak; and Dr. Shyamkant S. Talmale, Scientist C, Western Regional Centre, Zoological Survey of India.
Very little is known about this elusive animal.
Historically, the Manipur bush rat was recorded from Moirang in Manipur, Angarakhata in present-day Baksa district of Assam, and the Imphal region of Senapati district in Manipur. The species was first described from Moirang in 1886.
But the lack of recent records does not necessarily mean that the species has gone extinct. The researchers found no reported targeted field surveys specifically looking for H. humei in Northeast India since the historical collections. The rat is nocturnal and fossorial, meaning it spends much of its time underground, making it particularly difficult to detect.
Historical observations from Manipur linked the species with oak parkland and scrub on dry, undulating hills, where tall grasses grew over loose, rocky soil. Earlier observations also suggest that it feeds mainly on tender shoots and leaves.
The researchers suggest starting the search around its historical localities, particularly in Bishnupur and Senapati districts of Manipur and Angarakhata in present-day Baksa district of Assam. Similar habitats across the Indo-Myanmar and Bhutan foothill–Manas landscapes could also be surveyed.
September to December may be a good time for the search. The researchers recommend using live traps, pitfall traps, camera traps and night spotlighting, while also looking for signs such as burrows, feeding remains and droppings.
There is another mystery surrounding the species.
The Manipur records come from much higher elevations, around 900–1,300 metres, while the historical record from Angarakhata in Assam is from the foothills at around 100–200 metres.
The researchers say this striking difference needs further investigation. One possibility is that what is currently considered H. humei could include more than one species. Another is that the species may have a much wider distribution than previously known.
To answer these questions, scientists need more than field surveys. The genus Hadromys has never undergone a modern revision combining morphology, genetics and phylogenetic studies. There has also been no genetic research specifically on H. humei.
The Manipur bush rat is listed as Endangered by the IUCN and is protected under Schedule I of the Wildlife (Protection) Amendment Act, 2022. Yet, it has never been reported from a protected area within its known historical range.
For the researchers, finding the species would be about much more than adding another name to a wildlife checklist.
A rediscovery could confirm that this little-known evolutionary lineage has survived and could also tell scientists more about the condition of the oak parkland, grassland and foothill habitats where the species may still occur.
For now, the Manipur bush rat remains a mystery—” considered lost, but not confirmed extinct”. The researchers say focused field surveys, ecological studies and genetic research are urgently needed to finally determine whether this elusive rodent is still surviving in the wild.
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