Sally, I BELIEVE IT! Here is something I wrote about a similar encounter over the weekend when walking in the Little Otter Creek WMA accessible from Greenbush Road in Ferrisburg. There, I walked a couple of miles to the end of the access road:
3000 Common Grackle Quiscalus quiscula
At around 1:00, at the far end of the access road (near mouth of creek), the silent forest erupted in a cacophonus uproar of grackles. I counted by tens as large flocks (100 to 200 in number) launched from their cover in the crowns of mature foliated trees. It was spectacular to watch and hear as they took off from the trees (soft whooshing sounds as they flapped overhead). For thirty minutes I stood in one spot witnessing this: They would abruptly stop vocalizing just prior to the next flock taking off and then within seconds of the exiting flock's disappearance, the remaining birds would start vocalizing again. I estimated 1,200 flew past in front of me to be counted; there were many more behind my back and probably hundreds more further back in the forest, so 3,000 seems like a reasonable total count. I then walked to where they seemed to be heading and watched them forage in trees (eating acorns??? Acorns were dropping from mature oak trees full of the blackbirds), poking around in squirrel nests, feeding on the ground, and perching on understory.
----- Original Message -----
From: "Sarah Fellows" <[log in to unmask]>
To: "Vermont Birds" <[log in to unmask]>
Sent: Tuesday, October 6, 2015 8:54:48 AM
Subject: [VTBIRD] grackles
We were walking in deep woods in Williston Monday afternoon around 4pm when we heard a great cacophony just over and down a hill. My first thought was really late,really loud peepers, but then we came upon them and there were hundreds, if not thousands of grackles flitting in the treetops. Once we were underneath of them, we noticed we were being hit by stuff falling from the trees, hopefully not poop! It took a minute but finally it was apparent that it was bits of nut shell.THen we found whole opened beechnut shells all around us.The grackles were not there to roost for the night but were stripping the new beech harvest. We left them to gorge in peace.