I read an article about a year ago about why yotes howl, according to the article I read (to the best of my recollection) they do it for several reasons
the main reason is communication within the family pack. other reasons would include warning other packs to stay out of this territory or
if a pup becomes threatened the older yotes will run off a short distance and howl to distract and lure away any threats to the pups or their dens.
The article also mentioned that coyote howls are not malicious and coyotes don't associate howls with kills or food sources because that would only draw other packs into the areas... Foods are most often brought to the pups but pups have been seen at kill sites with the older coyotes.
Hope this helps.
