Shortage of hollows caused by extensive clearance for agriculture, felling of large trees and competition with Crimson Rosellas, Common Starlings (Sturnus vulgaris) and House Rats (Rattus rattus) is the cause for the decline of the Norfolk Island Boobook (Ninox novaeseelandiae undulata). The population of Norfolk Parakeets (Cyanoramphus cookii) increased after improved control of exotic predators (rodents, cats) and competitors (mainly Crimson Rosellas) and the provision and maintenance of predator-safe nesting sites. The adult wild population of the Norfolk Parakeets is now estimated to be 350–400 birds, after suffering from a population decline in 2013 (Garnett et al. 2011, Barnes 2017, Sperring et al. 2021).