re: duck hunting: what does "call sparingly" mean?

Also, what works one day may not work the next. Its all about reading the birds and that only comes with a lot of experience. You normally end up over calling or under calling the first few sets of birds. The key is to keep trying different combinations until you find the one that works. I've had days where you had to stay on them to finish them and some days where 5% more than they wanted to hear was too much and flared them. I normally let grays decide what they want without much calling at all. If you're hunting with multiple people you could all be blowing different calls...somebody on a whistle, another on a mallard hen, one with a gray call, etc. Don't overcall each one of them, but just hit them a little with each depending on how they react. Somebody else already said it, but being in the area they want to be in makes the best caller of all.