Pollardstown Fen is the largest remaining spring-fed fen in Ireland and is a very important site nationally and internationally. It is a post-glacial fen which began to develop approximately 10000 years ago when the area was covered by a large lake. Over time this lake became filled with dead vegetation which accumulated and eventually turned to fen peat. The calcium rich water found here prevented the usual change from fen to raised bog and continues to prevent this process today.
The fen is largely composed of reedbeds freshwater pools patches of scrubland and a large woodland area which lies at the western end of the reserve.
There are many rare plant species in the area such as Shining Sickle Moss and the rare arctic-alpine moss Homalothecium nitens. Other rare plant species include Narrow-leaved Marsh Orchid Slender Sedge and Marsh Helleborine.
Many resident bird species and also winter and summer migrants can be found in the habitat. Among them are regular breeders such as Mallard Teal Cood Snipe Sedge Warbler Grasshopper Warbler and Whinchat. Other species such as Merlin Marsh Harrier and Peregrine Falcon occur regularly as vagrants.
Situated approximately 2km north-west of Newbridge County Kildare.