Definitely need to cover the top with hardware cloth or a solid barrier because almost anything could climb in through the top. Coyotes can scale chain link easily if they're determined, although your bigger threat is probably raccoons or hawks. I would add 1/2" or 1/4" hardware cloth up the bottom 3 feet or so from the ground in addition to the chain link as well, because raccoons can stick their hands through the chain link to get at your babies.