Red Squirrels X Grey Squirrels: http://bsue53.wordpress.com/2014/02/21/landscape-scale-grey-squirrel-control-lessons-from-the-uk/comment-page-1/#comment-1
About Chester Zoo: http://bsue4b.wordpress.com/2013/12/26/chester-zoos-mission-by-mark-pilgrim/comment-page-1/#comment-4