Floating grass mats of the Northern Territory floodplains – an endangered habitat?

In 1920, a Northern Territory traveller and explorer, Carl Warburton, shot an egret near Cannon Hill, just west of the Alligator River (Fig 1). The bird fell some distance away across the plain, and with the intention of securing the plumes for a lady friend in Melbourne, he and a companion walked out to retrieve it. While doing so, they walked onto a patch of grass which started rocking under their feet (Warburton cited in Letts et al. 1979). Returning later they found they had been walking on a mat of grass floating over a waterhole which, they noted with dismay, was “infested with large crocodiles” (loc. cit.). This appears to be the first record of floating mats in the Northern Territory.