For two days at the start of monsoon season on the Indian subcontinent, male Asian common toads (right) turn bright yellow, while females (left) stay brown. Stückler et al. / Ichthyology & Herpetology ...

The color change, driven by hormones, seems aimed at preventing males from accidentally mating with each other. Two Asian common toad couples mating in Karnataka, India. The yellow toads pictured are ...