I'm a US native speaker who lives and grew up in the Northeast; my wife's from the Midwest. We both agree that in everyday English, the word "animal" refers to mammals--cows, squirrels, dogs, cats, bears, seals, etc. and that you would not refer to birds--not even chickens or turkeys--as "animals."

(Of course, in biology, "animals" refers to the entire animal kingdom--jellyfish, worms, insects, birds, and all--but that's not what I'm asking about).

I took it for granted that this was true of all English speakers. I was wrong. I was stunned to read a comment from James Osborne, a British speaker, in a question I asked about Spanish. He wrote:

<em>where I come from (the west midlands, UK) I don't know anybody who wouldn't consider birds to be animals. If someone asked me "What animals do you get in your garden?" I wouldn't list squirrels, cats, the occasional hedgehog maybe and then leave it at that. Birds would be first and foremost on the list. There's bloody loads of them.</em>

Dictionaries are not too helpful here.

American Heritage: "An animal organism other than a human, especially a mammal."

Oxford: "1.1 An animal as opposed to a human being. 'are humans superior to animals, or just different?’ 1.2 A mammal, as opposed to a bird, reptile, fish, or insect. ‘the snowfall seemed to have chased all birds, animals, and men indoors’"