Poetry, perfumed love notes, intimate e-mails and latenight phone messages have been the choice forms of communication for humans in love. Stags, on the other hand, have to rely on a simple, full-throated roar to convey their desire. True, the stag's primitive bellow is effective--smitten females approach while rival males look for cover. Likewise the cries of dogs, cats and birds all serve these animals well as simple forms of communication.