How much does a flock of birds weigh?

Last fall I spent a weekend at the Indiana Dunes State Park on the shores of Lake Michigan. Very cool place.

While out walking on a trail I encountered a sizeable flock of Common Grackles. As they noisily settled into the trees around me a steady shower of debris fell to the ground...twigs, small dead branches, acorns, etc. As they took off from the trees, even more stuff fell to the ground. I’m assuming the weight of the birds was causing this detritus to fall to the forest floor.

This experience got me thinking something I’d never thought of before: “How much does a flock of birds weigh?” When I got home I did some calculations and determined that 1,000 grackles weigh in at about 275 pounds. The flock of grackles I observed contained approximately 4,000 birds. This means that I was briefly in close proximity to a half ton of grackles! Wow!