I have just caught two this morning within 12 hours of having a new call bird on site. I've had about 20 so far this year, then gave it a rest for 2 or 3 weeks and now catching the new magpies that have moved into this territory.
My garden in full of song birds now after 4 years of persistent control
I feed my call birds a mixture of things... house scraps, egg's, horse course mix, chicken carcass... Just remember to keep them somewhere in the shade this time of year with plenty of water, they soon perish in the heat.
Happy Trapping