The Whistler's Warbler (Seicercus whistleri), a threatened migratory bird naturally found in the Himalayan ranges, has been observed in Sultanpur bird sanctuary in Gurgaon after some 25 years. Officials at the sanctuary claim, however, that eminent Indian ornithologist Dr Salim Ali could not observe the 9.5 cm to 12 cm long, yellow bird despite camping for long at the sanctuary.