Island ecosystems throughout the Pacific have undergone catastrophic species loss, largely due to the effects of alien or non-native species. Rats, in particular, pose significant threats to native species. In Hawai`i, the appearance of rats (which are not native to Hawai`i) in the subfossil record coincides with the disappearance of ground nesting birds. Sadly, only three of Hawai`i?s 10 endemic waterfowl species still exist today. The Laysan Duck (Anas laysanensis), also known as the Laysan Teal, is a critically endangered dabbling duck that is restricted to a single population on the remote and rat-free Laysan Island (Fig. 1). The Laysan Duck was listed as an endangered species in 1966 because of its small population, limited distribution, and dependence on a fragile island ecosystem. The same threats identified in 1966 continue to plague the species today.