The whistles with/pea can also get useless fast in sub-freezing weather. For upland bird hunting over setters and retrievers, I generally get my whistles and lanyards from Lion Country Supply. Here's a link: http://www.lcsupply.com/
I actually use the pealess British buffalo horn model. I know $18 for a whistle seems nuts, but I've tried a bunch of 'em and never found a model I like better for use in the field in any weather.