High Quality Content by WIKIPEDIA articles! The Bismarck Thicketbird (Megalurulus grosvenori) is a bird species. Previously placed in the "Old World Warbler" family Sylviidae, it does not seem to be a close relative of the typical warblers; probably it belongs in the newly-recognized grass-warbler family Megaluridae. It is found only in the rarely visited highlands of the island of New Britain in Papua New Guinea.