Spring Birds working to the calendar

From the garden birds it would seem that most have their clocks set about right. I'm refering to the facts that some birds are out of sync with their traditional breeding patterns or more specific out of sync with their peaks in their food sources. So our Blue Tits which now seem to be now egg laying on the face of it for mid April seem to be laying at their traditional time. But problems may occur if the Moth caterpillars they depend on as a food source for fledglings have already peaked.