• Brown Rat
• Common Pipistrelle
• Common Shrew
• Fox
• Grey Squirrel
• Hedgehog
• Mole
• Rabbit
• Roe Deer
• Soprano Pipistrelle
• Weasel
• Wood Mouse

These mammals in italics have been seen in the Gainsborough area but not in Mercer Wood

• Badger
• Brown Hare
• Field Vole
• House Mouse
• Mink
• Noctule
• Stoat
• Water Vole