Uttarakhand will have to start the tiger estimation exercise in a 108sqkm area of Corbett Tiger Reserve again after torrential rains swept away 27 camera traps installed inside the reserve. “Data captured in the camera traps — covering 108 sq km — is lost now. The tiger estimation exercise in the area will have to be started from scratch,” R K Tiwari, warden of the reserve, told TOI. The reserve area spans 520sqkm. The camera traps were installed earlier this month to track the tiger count of the area for a nationwide estimation exercise. Corbett authorities said 494 camera traps had been installed in Ramnagar division. Almost all zones of the reserve lost camera traps, but Dhela zone — which lost 10 — and Bijrani zone, where four camera traps were washed away, were the worst affected.