Jan. 31, 2026 under clear skies, northwest wind at 5 mph, 19°F; sunset at 4:56 PM. An evening of classic winter crow winter roosting behavior unfolded along the Merrimack River corridor, with multiple staging areas active and a dramatic build up toward an established overnight roost. It was a pleasure to welcome two groups of guests, with Abby and Eric below!

In addition were were joined a bit later with Peter, Lynne, and Jack after they hiked in the heavy snow out to the middle of the O’Leary Bridge!

The outing began with initial stops along Merrimack Street, followed by the Casey Bridge area, before settling in near the Great Stone Dam. Crow activity was widespread and immediately apparent. Large numbers were perched in leafless trees lining the south side of the Merrimack River, with additional concentrations in trees on both sides of the dam. Steady flight movement along the south bank of the river hinted early on that a significant roost buildup was underway.

In addition to continuous incoming flight streams, thousands of crows gathered on the snow-covered river ice just upriver from the dam. This ice staging area served as a temporary assembly location, with birds repeatedly lifting off, resettling, and reshuffling as more arrivals poured in from all directions. The contrast of dark birds against bright snow and colorful sunset sky made the scale of the gathering especially striking.

On the downriver side of the dam all around the O’Leary Bridge, the spectacle intensified. Endless flight streams crossed over the river, punctuated by dramatic bursts of tightly packed birds erupting into the air. Loud, raucous vocalizations filled the corridor as crows surged, circled, and regrouped, creating a dynamic and constantly shifting aerial display that held everyone’s attention.

As dusk deepened, large numbers began concentrating in the trees at the far west end of Pemberton Park on the north side of the bridge. The steady accumulation here marked the final phase of the evening’s movement. This location has served as a regular overnight roost in prior winters, and once again it proved to be the focal point as the crows settled in for the night. Another dazzling winter crow spectacle, and a memorable evening out on Crow Patrol, made even better by welcoming visitors to share in the experience.

For the 2025 National Audubon Christmas Bird Count (CBC) for the Andover Circle (MAAN), the dedicated crow roost count totaled 14,025 crows, including both American Crows and Fish Crows. By comparison, the Andover Circle crow count was 12,550 in 2024 and 11,600 in 2023. Many thanks to Mark Morroni and Donna Cooper, who coordinated and compiled the Andover Circle CBC this year. Craig serves as the designated sector leader for the Lawrence winter crow roost count.

The counting methods developed by the Crow Patrol for the Lawrence roost were formally reviewed and approved in January 2021 following a detailed evaluation of field notes, images, and group discussion with Wayne Petersen, New England Regional Editor for the CBC, with full support from Geoff LeBaron, National Director of the CBC, and Donna Cooper as local compiler. After this comprehensive review, the 2020 CBC American Crow count was finalized at 15,200, a figure fully supported by field documentation and consistent with long-term observations by experienced local birders.

Building on guidance from the National CBC leadership, we now use enhanced, field-based counting methods tailored to large winter crow roosts. These include multiple direct block counts of birds in flight, during staging, and once perched, conducted entirely on foot around the roost. Counts are later cross-checked using still images and video, supported by modified open-source counting software. This multi-layered approach significantly improves accuracy and repeatability. A detailed overview of these methods is available in the Winter Crow Roost Counting Guide (PDF) on the main page.

All images are captured using professional low-light mirrorless camera systems and fast-aperture lenses, allowing for reliable documentation under the very challenging lighting conditions at dusk and after dark typical of winter crow roosts.