Yep, the credits' spelling is I-C-H-Y, which is pronounced the same as “icky”. His scientific name, Ichthyornis, is pronounced “Ick-thee-or-niss”, but I guess the filmmakers thought that “Ichy” sounded better than “Ichthy”, so they removed a syllable. A name that sounds like “icky” kind of works for his character, too, possibly implying that he is unpleasant and repulsive (which, from the gang'sóand Dil's :póstandpoint, he is).