Recent emails about Song Sparrows and others feeding young Cowbirds got me thinking and wondering about something....
I assume that hosting parents of Cuckoos feed them what they instinctively feed their own young.  I can't imagine a seed-eating parent fulfilling the nutritional needs of Cuckoo nestlings when adults (I understand) feed almost exclusively on insect fare, primarily caterpillars.  Do adult Cuckoos, or Cowbirds for that matter, seek the nests of species that feed their young the proper diet?
To the extent that fledged Cuckoos learn gleaning techniques from observing their parents, how is it that they successfully feed themselves as adults without that example?
I'm sure I'm not the first to wonder about this.  Answers, anyone?