I had the same thing happen to me while turkey hunting this year. I heard a siren, and all of a sudden the yotes really started howling. They were real close too, I'd say within 100 yards, and it sounded like there were quite a few of them too. I saw a small hand held siren locator call in one of my magazines that was pretty reasonable, it might be worth checking one out. Good Hunting .... SHOTARYE