Black squirrel

From Tardis Wiki, the free Doctor Who reference
Black squirrel

Black squirrels were small mammals native to some Earth nations such as Russia, but not England. Dodo Chaplet once saw some scampering through a forest soon after disembarking the TARDIS in 1812. She used their presence as evidence the First Doctor had not taken her and Steven Taylor to England as promised. (AUDIO: Mother Russia)