Invasive Eurasian Tree Sparrows Passer montanus on Troughton Island in the North Kimberley of Western Australia: A cyclone-induced colonisation attempt?

Abstract

Four Eurasian Tree Sparrows Passer montanus were recorded on Troughton Island, north-western Western Australia, on 6–8 August 2016. Reports indicate that these were the remaining birds (or progeny) from a group of 17 birds that arrived after a storm in c. 2011; the population then dwindled despite apparently breeding over the next 5 years. This represents the first documented colonisation by this species of a near-shore location in Australia with little or no likelihood of ship assistance.