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The fates of 2 autochthonal rat taxon – the Elvira rat (Cremnomys elvira), which is critically endangered and the much commonly seen Cutch stone rat (Cremnomys cutchicus), exemplify however taxon adaptability to a circumstantial scenery impacts their chances for success, wildlife researchers studying the 2 taxon state.
“The rocky hillocks and granite inselbergs of Madurai territory are not places astir radical subordinate with wildlife watching. Scrub vegetation clings to bladed soils betwixt exposed boulders; the scenery looks spent successful the adust months, astir inhospitable. But for C. cutchicus, this is premier existent estate. During nocturnal transect surveys crossed 3 sites successful the rocky terrain southbound and eastbound of Madurai, conducted betwixt 8 p.m. and midnight crossed aggregate evenings,” according to R. Brawin Kumar, a wildlife biologist studying lesser known taxon of fauna successful Tamil Nadu. He noticed the Cutch stone rat successful areas with “large, jointed granite blocks offering heavy crevice systems.”
He besides recorded the beingness of the taxon successful the Shervaroy Hills of Salem, which is location to the critically endangered sister taxon of the Cutch Rock Rat – the Elvira Rat. Unlike the former, the Elvira Rat is restricted to a circumstantial Shonkinite stone enactment successful the Shervaroy Hills. Shonkinite is besides 1 of the rarest geological stone types successful the world.
“Interestingly, The Cutch stone rat was observed successful adjacent rocky areas with antithetic lithology, suggesting the 2 taxon whitethorn partially overlap successful geographic abstraction portion partitioning microhabitat by stone type, a question that warrants dedicated survey efforts,” said Mr. Kumar.
The Cutch stone rat makes its location successful the stone crevices and thrives successful the granite rock’s thermal stability. “The Aravalli Range, the superior stronghold of C. cutchicus successful Rajasthan, is 1 of the world’s oldest geological formations, believed to beryllium betwixt 1.5 and 3.2 cardinal years old, formed during the Precambrian era. The rocky outcrops of Tamil Nadu, portion geologically chiseled (comprising Archaean gneisses, granites, and the uncommon Shonkinite of Salem), are comparably ancient. This rat has not simply adapted to aged rocks, it has co-existed with immoderate of the oldest onshore surfaces connected Earth,” helium said.
Mr. Kumar believes the comparative occurrence of the Cutch stone rat successful examination to its sister taxon The Elvira rat is owed to its adaptability to antithetic stone types. “The Elvira rat is tied to Shonkinite, an highly uncommon intrusive igneous stone recovered successful lone a fistful of locations worldwide, with small, localised outcrops. The Elvira rat is recovered lone successful Salem and obscurity other successful the world. The Cutch stone rat, by contrast, tolerates a wider assortment of rocky substrates, granite, quartzite, basalt, Deccan Trap formations, and has truthful maintained a broader distribution,” helium said.
The critically endangered Elvira rat | Photo Credit: R. Brawin Kumar
However, helium cautioned broader organisation does not mean the taxon is without threats, with the stone rat’s superior ecosystems successful the Aravalli upland scope nether superior menace implicit the coming decades owed to mining, contempt the species’ beingness successful Theerthamalai successful Harur division, Salem and Madurai arsenic good arsenic successful different medium-sized rocky hills.
“In Madurai and Salem, the southernmost confirmed tract localities for this taxon based connected caller observation, the menace illustration is different. Here, the unit comes not from mining but from urbanisation expanding into the rocky scrubland margins of the city, and from the conversion of rocky slopes adjacent Salem for concern use. The confederate colonisation of C. cutchicus, if genetically chiseled from bluish populations (a question unanswered by immoderate published molecular survey to date), could correspond a conservation portion of autarkic significance,” helium said.
Mr. Kumar, a recipient of the Tamil Nadu Environment Award successful 2016 and the Tamil Nadu Green Champion Award successful 2022 told The Hindu the stone rats are superior nutrient sources for taxon specified arsenic the Bengal fox, arsenic good arsenic for a fig of raptor species. “Their extortion and beingness successful these landscapes is important for the section rocky ecosystems they inhabit,” helium said.
