Gerrit has spent the non-breeding period (northern winter) along the Waanje River near to Tye village. A visit to the site in February 2009 has discovered more than 60 Purple Herons living along the river, which indicates that this is probably one of the internationally important non-breeding areas for the species.
The Waanje River is situated in Bonthe District, in the south eastern corner of Sierra Leonne. It is an unregulated river which flows parallel with the coastal dunes between Lake Mapi and the Seewa River.
The river is followed by extensive marshes, ricefields and, on the higher grounds, small plots of cultivated areas.