Originally this whole passage describing the geography was in the past tense, but in one place the 1837 typesetter replaced the past-tense was with is, probably by mistake since the change was not marked by Joseph Smith in the printer’s manuscript and this change contradicts usage elsewhere in the verse as well as in the following verse:
In general, the Book of Mormon text uses the past tense to refer to geographical descriptions that would have still held true at the time the historian wrote the passage (see the discussion under 1 Nephi 2:5 and Alma 8:18). The critical text will restore the past-tense was here in Alma 22:31.
Summary: Restore in Alma 22:31 the past-tense was in the geographical description found in Alma 22:31: “it being the wilderness which was filled with all manner of wild animals of every kind”.