The crow, thinking that this number of men had passed by, lost no time in returning.' From this he inferred that crows could count up to four.
Lichtenberg mentions a nightingale which was said to count up to three.
Every day he gave it three mealworms, one at a time.

When it had finished one it returned for another, but after the third it knew that the feast was over....

There is an amusing and suggestive remark in Mr.Galton's interesting _Narrative of an Explorer in Tropical South Africa_.

After describing the Demara's weakness in calculations, he says: 'Once while I watched a Demara floundering hopelessly in a calculation on one side of me, I observed, "Dinah," my spaniel, equally embarrassed on the other; she was overlooking half a dozen of her new-born puppies, which had been removed two or three times from her, and her anxiety was excessive, as she tried to find out if they were all present, or if any were still missing.

She kept puzzling and running her eyes over them backwards and forwards, but could not satisfy herself.