The Darwin’s frog, with its ebullient croak, heralds the arrival of spring. These small, colourful frogs are native to Chile and Argentina, where they live in humid forests and grasslands. They are easy to identify by their mottled orange and black body, white belly and distinctive cranial crest. Darwin’s frogs are also unusual in that they can change colour; they may be light green or brown when inactive, but turn brilliant yellow, red or blue when agitated.