Downtown crow roosts topic of informative talk
Downtown Williamsport has a few hotels, though not just ones for people, according to a Penn State University wildlife resources professor.
“Crows have always been in our area and are a helpful part of the ecosystem,” Dr. Margaret Brittingham told an audience that attended her discussion of “Urban Crow Roosts” at the Lycoming Audubon Society meeting earlier this week. “They started moving to cities in the 1970s. They like medium-sized cities with rural areas around them.”
The birds like the light and heat offered in urban settings that also offer protection from predatory owls, she said. They do not typically feed in cities but “use them as a hotel.”
However, their movement into cities has caused problems that must be managed — or sometimes even moved.
One of the most important insights in terms of controlling roosting location is recognizing they start their roosting behavior in the fall, with a peak roost size in December. The large roosts continue to decline until February.
“If you want to move crow roosts, get started in the fall when roosts of migrant crows start to form,” Brittingham said.
Crows need to roost somewhere. In cities, they make use of trees and flat-roofed buildings.
If city administrations want to change that, she said, crows need to be encouraged to roost in a new location by using harassment techniques. These techniques include pyrotechnics, lights and crow effigies.
Crow effigies are usually paper cutouts that look like a dead crow. They are hung upside down in a visible location.
Pyrotechnics can sound like gunfire and need to be accompanied by an effective public awareness program. Laser lights are often restricted because of proximity to airports.
Brittingham said city areas should be characterized as either no tolerance zones; moderate tolerance zones; or high tolerance zones. In a high tolerance zone, the crows are left alone. The goal should be to move the winter roosts to these high tolerance zones.
Crows want to roost near one another. Therefore, when crows are encouraged to roost in a high tolerance zone in the fall, others crows will aggregate there rather than in no tolerance zones. After a few years of directed harassment in Lancaster, no harassment was required for several years, Brittingham said. Now only minor, targeted harassment is required to keep them away from no tolerance zones.
Moving crow roosts requires understanding their behavior, said Brittingham, who has researched crow roosting problems in Lancaster and State College.
She said the species’ social behaviors include their desire to see each other at night, reliance upon sentinel birds to warn the flock, travel behavior and assistance provided by juvenile crows.
Crows typically feed in the countryside but, in the late afternoon, they will start staging in fields near their roosts. As darkness falls, they will take flight and head to their evening roost. The night-time roosting flight is contorted and loud, much different than the more orderly exit in the mornings.
Following Brittingham’s talk, Chelsea Myers, Williamsport city planner, discussed the five roosts in Williamsport and the effectiveness of using lights and the surprisingly good results of a disco ball in an upper floor of the Bullfrog Brewery, near one of the largest roosts.
City Councilwoman Liz Miele is taking the lead on the crow roosting problem.
After the presentation, Gary Metzger, vice president of the Lycoming Audubon Society, asked about volunteer needs. Myers said the city would like volunteers to staff seven groups that go out one night per week to conduct crow harassment.
Dave Ferry asked about using drones as a harassment device. This led to a lively discussion because the idea had not been considered in Brittingham’s previous work. The idea was well regarded but moderated by concerns of losing control of the drones or having them damaged.