They will respond to it nearly always unless it has been overused then like anything else they get used to it. There are some that won't talk if they have really young pups, or if you are too close to them with it. A lot of the time after you locate them with the siren, they will come towards it, so then you won't be able to call them by going to where they were and calling them with distress calls. It normally takes them about half an hour till they will talk or respond to howls after they have talked. That's why I like to use it to locate the adults for the aircraft and the pups when they are old enough that they will howl in response to it. As with all of my calls I have times of the year that I like to use them better than other times of the year so that I don't have them used to my calls. I know that there are coyotes that hear my calls and might be in another territory when I'm calling so they don't get to me before I shoot the coyotes that I am in their territory and that will teach them about that sound and a loud noise that is associated with it, making them cautious when they hear it.