Complete Bird Brains

There are many species which enjoy snacks of suet, and almost none more enthusiastic than the American Robin. But unlike most of the other power suet hitters (e.g. Red Bellied Woodpeckers, Carolina Wrens, Eastern Bluebirds), the Robins don't seem particularly endowed with brights---or at least memory. I watch these birds successfully get atop a hanging basket, and other times attack it as if never having seen it before. They'll also go for a woodpecker-friendly feeder that in no way can accomodate them, ignoring the basket less than two feet away. Do they not learn? Why is a successful method so often followed up by a stupid approach? Truly these characters are bird brains.