The crows are back in town.
Following their pattern of prior years they’ve begun their winter roost in Oakland and will slowly adjust its location until by December they’ll gather west of Polish Hill and roost in the Strip.
Or maybe not. It remains to be seen.
Right now they fly over Peter Bell’s apartment every night. On Sunday he shot this video of them flying southwest and pausing on the trees nearby.
Peter wrote on YouTube, “Every fall thousands of crows gather in Pittsburgh. I was lucky enough to be in a spot they all decided to pass over as they decided on a place to roost for the evening. On this night, it took about 40 minutes from the first few I noticed until most had passed by. This night they weren’t being too noisy, so most of the recorded audio was buses and other traffic, so I swapped it out. Music: Schubert’s Serenade (Lied from Schwanengesang D.957) recorded by Anne Gastinel”
Inevitably a flock this large makes us wonder: How many crows are there? How do you even estimate their number? Here’s how.
- Note the starting time. (For example: 5:45pm)
- Pick a reference point in the scenery.
- Use a timer and count the number of crows passing the reference point for 1 minute or 3 minutes, whichever is most useful. Make several of these timed counts so you can get a decent average of crows per minute.
- Now relax and watch the crows passing by. If their concentration increases or decreases noticeably, redo the timed counts.
- When the crows taper or stop coming, note the ending time. (For example: 6:30pm)
- For how many minutes did the crows pass the reference point?
- Use some easy algebra: minutes * crows/minute = crows.
You can try this while watching Peter’s video. Count the number of crows exiting the frame, then multiply by 40 minutes.
How many did you count?
(video by Peter Bell)