Dec. 16, 2023 under clear skies, wind E at 12MPH, temp 45F; sunset time 4:12PM
Out on Crow Patrol for the 2023 National Audubon Christmas Bird Count. From early scouting trips, staging Crows were seen in the extended boathouse area along the Merrimack River west of the Stone Dam, near the airport, and all along Market Street and the South Common park. By 20 minutes after sunset time the incoming flight streams picked up volume.
The Crows were seen landing on the roof at west end of New Balance building and flying over the roof top at the Mill240 building.
The Crows also built up big numbers on the roof at former B&D warehouse building with loud vocalizations, and then went back and forth in flight waves when trains went by or due to other loud noises, crossing by the Ayer Mill Clock Tower!
Thanks to special aerial imaging capabilities we had spectacular views overlooking the warehouse roof tops at close 40 minutes after sunset time, and prior to flight movement towards the New Balance roof and the overnight roost. This view shows about 205 feet in length for this section of roof and about 70 yards across. The regulation size for a football field is 120 yards long and 53 yards wide!
The numbers picked up substantially over next 25 minutes until the Crows converged into the overnight roost trees on the north side of the New Balance building and in trees behind National Grid. Again, with these special aerial views, we were able to better assess overall concentrations and make specific counts. This image below about 55 minutes after sunset time.
The aerial survey work continued with manual camera settings to achieve proper exposure levels under challenging lighting conditions on the east side of the Duck Bridge. Although the well lit parking areas are overexposed, the roost trees have sufficient highlights for count purposes. This image a few minutes later.
After double checking all of the prior vantage points, we positioned ourselves in the middle of the west side of the Duck Bridge for final observations. Although unexpected, we had a number of intermittent flight bursts from the roost trees in big loops out over the Merrimack River and back to the roost trees.
The overall action around the roost finally quieted down in both noise levels, flight action, and even smaller intra roost minor movements. It is always a special moment to observe the complete roost area, with extraordinary ambient lighting, from end to end, with the Merrimack River flowing below, and the Crows all seemingly tucked in for the night in the Crow dormitory! This image with low light camera gear and long exposure capture methods. It was another dazzling night!
For the 2023 Audubon Christmas Bird Count (CBC) for the Andover Circle, this separate Crow Count was 11,600 total Crows, including American Crows and Fish Crows. In 2022, the CBC Andover Circle Crow Count was 13,750. Many thanks to Donna Cooper who coordinates and compiles the Andover Circle each year!
Note on counts/estimates: we are now using improved methods for counting the large number of Crows while streaming, staging, and in the roost. For all images, we use both a modified open source counting software program, as well as a hand count approach, while outside next to the roost, to carefully document our observations and to significantly increase reliability and accuracy of the presented numbers. Please refer to our new roost counting guide on main page.
The Canon mirrorless cameras with the RF 50mm f/1.2 lens and the RF 28-70mm F2 excel in low-light conditions, blending versatile focal lengths with an ultra-wide aperture. Both focal lengths work extremely well in very low light conditions, while the f/1.2 and F2 aperture settings ensure exceptional performance in low light conditions, offering stunning clear, and aesthetically pleasing images, making them ideal for the challenging very low light conditions around the overnight roost.
For all aerial documentary films with migratory and/or wintering birds or other wildlife, advance project planning and aerial imaging flight mission protocols are subject to rigorous review for “no disturbance” to any flight and perch behaviors, use of high resolution/optical zoom optics, overly cautious altitude/buffer zone levels, and low noise signature levels; all to avoid even the smallest disturbance on these migratory and/or wintering birds.
Remember to check out the latest Crow Patrol Podcast with John Macone (Merrimack River Watershed Council): wintercrowroost.com/podcast/
Photo gear used for most outings:
Canon EOS 80D with Canon EF-S 18-135mm f/3.5-5.6 IS
Canon EOS 80D with Canon EF-S 18-135mm f/3.5-5.6 IS (Infrared)
Canon EOS R6 Mirrorless with Canon RF 28-70 f/2 L IS USM
Canon EOS R6 II Mirrorless with Canon RF 50 f/1.2 L USM