Today is a special milestone for our furry, scaly and feathered friends: the Endangered Species Act is turning 50. This landmark US legislation, signed into law in 1973, has been lending a helping hand to species on the brink for half a decade. The act helped inspire Britain's own Wildlife and Countryside act of 1981. Who's that in the spotlight? A humpback whale! Known for their haunting songs and acrobatic breaches, these gentle giants are a success story of the ESA. They were once on the edge of extinction due to whaling and entanglement in fishing gear, but thanks to conservation efforts, their population is making a comeback, from around 5,000 in 1966 to an estimate of 135,000 today.