The Mammal Atlas has been recently retired however you can use the Aderyn website https://aderyn.lercwales.org.uk to look at distribution maps across Wales. It pulls together data held by Cofnod (North Wales's Local Environmental Records Centre) as well as the other 3 Local Environmental Records Centres in Wales.
Records to Add?
Submit records using Cofnod's Online Recording System (ORS). It is ideal for anyone who records wildlife, but would prefer not to store the records on their own computer. Register once and get loads of great features.