Okay, so I emailed the creator of Wilber, Tuomas Kuosmanen, about what Wilber really is. My email to him is as follows, copied and pasted:

Tuomas,

Are you the same person that designed Wilber the GIMP? If so, I have a question. Is Wilber supposed to be a known animal, or is he a GIMP, as Gimp.org says? Some say he's a coyote, but I tend to believe what GIMP.org says. Could you please clear this up for us. GIMPWIKI says he's a coyote as well, so some believe that. Also, did Wilber ever have a body, or just a head, as it's known now? Please clear this up for me. Would be great to hear it coming right from the person's mouth that created him. Thanks!

Jim

His response, also copy and pasted:

Hey, yes I am. :-)

You are correct: Wilber is an animal of its own species: a "gimp".
What a GIMP is, is sort of a joke, because people kept asking it so
much: it would be so boring to say it's a dog or a fox or whatever.
And when I designed the character, I did not really have any
particular animal in mind. - so it's sort of a mystery without any
explanation.

It also does not have a body. I think I have seen an image years ago
when someone did a body for it, but not in general.

Have a good day! :-)

//Tuomas

So, GIMP.org is correct.

Haha, I'll bet he does too.

I was feeling a bit berated from these three threads, so I thought I would find out:

http://www.gimpchat.com/viewtopic.php?f=11&t=254

http://www.gimpchat.com/viewtopic.php?f=26&t=10248

http://www.gimpchat.com/viewtopic.php?f=11&t=10256

I really didn't care what Wilber was, mind you, I just felt that GIMP.org knew what it was talking about. Turns out, it did.

Wilber is what a Goat

so maybe you guy's didn't get it,
Wilber is like me.

an Old GOAT

OK, if this is the post of mine, that stay's on top the longest
then clearly i am doing something wrong, or maybe i have missed my calling
completely. Well what the hell, i think all the art work i have seen here is great
is great, and i have not read a bad post. Thank you for the excellent
education. GIMP CHAT is truly a remarkable website, and compared to
all other sites this is above the others.

I got it Mike but I am still trying to figure out the four images. I can't seem to see any differences in them, probably because they aren't side by side.

You're an old goat, got it, but why post the same photo 5 times? It was late last night when I posted this, so nobody to answer you.

Thank you The Warrior, very cool of you tracking down the original designer.

Warrior, nice to clear that up, I didn't think he was supposed to be any particular animal and I'm glad that it was just supposed to be the head, a body would just add to the animal confusion.