Sheep have been trained to recognize human faces [bbc.com], such as that of Baaahrack Obama [theguardian.com]:
Sheep have demonstrated the ability to recognise familiar human faces, according to a study. Cambridge University researchers were able to train sheep to identify the faces of actors Jake Gyllenhaal and Emma Watson, former US President Barack Obama and BBC newsreader Fiona Bruce. After training, the sheep chose photos of familiar faces over unfamiliar ones significantly more often than not.
It shows that sheep possess similar face recognition abilities to primates. Previous studies had shown that sheep could identify other sheep and human handlers that they already knew.
"What we did is ask whether a sheep could learn to recognise someone from a photograph," the study's lead author Prof Jenny Morton said. "We focused on whether or not an animal was capable of processing a two-dimensional object as a person."
PAPER TITLE NOT YET AVAILABLE (DOI: 10.1098/rsos.171228) (DX [doi.org])