Green faeces,mammal or bird

Green faeces,mammal or bird

Observation - Green faeces,mammal or bird - UK and Ireland. Description: Light green coloured faeces, when teased out seemed to be most undigested grass.(Photo 2). From size and colour could this be a Mink. The site is on a culvert over a stream. Why would it be eating grass?

Light green coloured faeces, when teased out seemed to be most undigested grass.(Photo 2). From size and colour could this be a Mink. The site is on a culvert over a stream. Why would it be eating grass?