Rajah Brooke’s Birdwing butterfly

Trogonoptera brookiana

With magnificent wings spanning 7in (17cm), I was initially drawn to this butterfly purely for its striking appearance. But I discovered something quite fascinating; Juvenile males can only become adult by drinking mineral water. They gather in groups of up to 80 to drink from puddles to absorb mineralized water containing the sodium and potassium ions needed to activate adult behaviour.