An Astonishing Phenomenon
You know about the crows if you drive north or south on I-495 at sunset over the bridges spanning the Merrimack River in northeast Massachusetts. This massive crow population roosts in the city of Lawrence starting in the fall around October and continuing into March. The population is estimated to number in the thousands, upwards of 15,000 in the coldest months.
Why the crows chose Lawrence for their annual roost is unknown. Other cities or locales experience the same phenomena. What makes Lawrence unique is the city embraces the crows instead of trying to discourage their presence. There are art exhibits, lectures, blogs, and crow patrols. The latter are late day or evening walks along the Merrimack River to observe, monitor, document, and photograph the crows jostling for space as they settle in for the night.
For years, my route to work took me over the Lawrence Bridges. On my evening commute, I hoped for traffic delays approaching the bridge to savor the spectacle of hundreds of large, noisy birds swooping over our cars to their roosts in the trees along the river or under the bridges. In anticipation of my nightly treat, I would silence the car radio and lower my windows to enjoy the cawing and sounds of hundreds of flapping wings.
In the morning the birds leave the city for their feeding grounds. I have read their daytime roaming range is about 20 miles from their roost. I am sure the crows that frequent our yard fly in from Lawrence, a short 15-minute car drive and a shorter more direct route by wing power.
Retirement has ended my enjoying the nightly spectacle except on rare occasions when some event offers me an opportunity to cross the Lawrence bridges at sunset. You can be certain I will take that route even if it adds additional time to my drive.