I've had mixed results with the calf in distress sound. It's been my experience that it works better in mid summer to early fall than right now. I suspect it has something to do with the fact that when trying to take down a calf, it's usually better coordinated by a mated pair and their adolescent pups. This time of the year, one of the mated pair are usually staying in the "den area" while another goes out to collect food. The actual attacks that I've seen on calves usually have one of the mated pair holding the mother cow's attention, the other rushes in for the kill. Once the pups are old enough to leave alone or go hunting with their parents, you'll probably have better luck with the call. (I'd say wait until late June or early July). Also, be prepared to have the entire herd of cows respond to your call if you're hunting in a location where they are present. In the event, there are not any cows around, the yotes probably aren't familiar with the sound and whats required to take down a calf. If that's the case, go ahead and use it as yotes are curious and will come into any new distress sound.