I agree, they are smarter than most people give them credit for!
Video - I call my chicken and turkeys with whistle - Page 2
Joking aside, I've always whistled for my girls, imitating their own 'good food' sounds, but I think I'll readjust their little brains to a louder whistle so they can hear me better when it's windy, etc. Great Idea!
Hmmmm.... I have a dog-whistle too. How good are chicken ears for that high of a frequency, I wonder?