thumb|Hen Poo and Duns CastleDuns Castle nature reserve is a nature reserve near Duns,[1] in the Scottish Borders area of Scotland, in the former Berwickshire.
It consists of two man-made lakes, Hen Poo and Mill Dam; apart from the wetland, there are extensive woodland areas.
Places nearby include Abbey St Bathans, Chirnside, Ednam, Fogo, Gavinton, Polwarth, Preston.