As an engineer, I have to respond to physicist Maurice Barnhill’s 
posting to DE-bird January 25 about estimating the size of a large 
blackbird flock. December 29 I saw a large flock of blackbirds along 
Egypt Road on the way to Blackwater NWR. My 2 sons and a grandson were 
with me. I reported the flock on MDOsprey as 100,000 birds, which I 
considered a conservative estimate. Those with me were guessing several 
hundred thousand.

It is difficult to think back in retrospect and estimate the dimensions 
of the field where most of the flock was for part of the time, but I 
think 1,000 by 500 feet is reasonable. I reduced the area required by 
each bird from 6 (Maurice’s estimate for grackles) to 5 square feet, 
since about half of the flock were Red-winged Blackbirds and 
Brown-headed Cowbirds, the rest Common Grackles. Interestingly enough, 
doing the math that Maurice suggested yields 100,000 birds.

This is still a conservative estimate, as thousands of birds were always 
flying or perched in trees along the field edge.


Cliff Comeau
Beltsville, MD