At Woodside Park yesterday afternoon I observed a Warbling Vireo feeding a cowbird chick. The chick had fledged and was perched on a tree branch while begging insistently. The vireo responded by bringing food to the chick on several occasions. There were no vireo chicks in sight. The cowbird fledgling was larger and bulkier than the vireo adult, yet the vireo kept on coming. I have read about this behavior, of course, but had never observed it in nature before. I didn't know whether to laugh or cry. I did both.