The change happens fast
For most of the year, the Indian bullfrog (Hoplobatrachus tigerinus) is a forgettable shade of olive-green or brown, blending into the muddy margins of ponds and rice paddies across the subcontinent. Then the first monsoon rains arrive, and the males change within days. The dorsal skin shifts to a bright, almost aggressive yellow. The vocal sacs, the paired pouches that inflate when a male calls, turn a striking blue-violet. No other Indian amphibian undergoes a colour shift this dramatic or this fast.
