What were the borogoves like in Jabberwocky?

In Through the Looking Glass, Humpty Dumpty defines a 'borogove' as, "a thin shabby-looking bird with its feathers sticking out all round -- something like a live mop." Sixteen years earlier, Carroll described it in this way, "an extinct kind of Parrot. They had no wings, beaks turned up, made their nests under sun-dials and lived on veal."