There have been a ton of eastern bluebird flocks milling about when I've been doing my fall surveys. Their calls follow me everywhere on my surveys...and they always sound like they are apologizing for something.
One of the birds caught my attention because he was just wacking the crap out of something on the fence post. I've seen birds do this with large mealworms or other bugs. I was curious about the prize the bluebird had.
It was a woolly bear caterpillar. I figured the bluebird wanted to subdue the large caterpillar before swallowing it but seeing that it was a woolly bear and that the stripe in the center of a woolly bear is supposed to predict the how harsh the coming winter will be, I can only assume that this bluebird is still bitter about how long and snowy last winter was and is not thrilled with the prediction for this winter.
Hey, if you're not squeamish about handling live mealworms, here's a video I found of someone who uses them to hand feed bluebirds: