The Australian Silver Kookaburra series from the Perth Mint began in 1990 and is the longest-running bullion program from the mint. Each year has a differing design of a kookaburra on the reverse. This bird species is indigenous to Australia and is known for their call, which is said to sound like echoing human laughter. Silver Kookaburra coin has been a maximum of 300,000 coins. However, in 2011 the maximum mintage was moved to 500,000 coins to accommodate the very high demand for this series.