Conditions: clear skies, wind N at 5MPH, temp at 35F: sunset time 4:14PM

Out on Crow Patrol for almost two hours, starting just before sunset time with looks at staging Crows near the airport and along the Merrimack River. Next stop was along South Canal Street with Crows arriving minutes before sunset time with lots of vocalizing. Huge streams of incoming Crows from upriver and to the west were observed over the next 40 minutes, streaming in over the uplit Casey Bridge with lingering sunset colors fading in the distance.

The Crows gathered in a massive buildup around the the truck depot area and the next door National Grid facility. The perched in trees, rooftops, on utility wires, and in big numbers on the ground. This image was captured with night vision optics about 25 minutes after sunset time.

Even though wind was light, large numbers of Crows (7500+) were seen settling in and perching in the trees along the Merrimack River at the very rear of the truck depot lot well after sunset. The core concentration for the overnight roost seems to have made a shift slightly to the east of the general overnight roost area by the New Balance building. This image was captured about 30 minutes after sunset time.

At times, the Crows made upward flight bursts and settled back down right. back down. At times they react to loud noises, like very loud trucks, nearby sirens, and even motorcycles with very loud exhaust sounds. But tonight, from a distance, and under diminishing light conditions, the disruption was more like what we might see from a Great Horned Owl flyby. This image is a bit blurry, but captures the flight burst at about 38 minutes after sunset time.

Again, looks like the core of the roost has shifted a bit to the west and away from the New Balance building! This last image was captured about one hour and 15 minutes after sunset of Crows milling around on the on the ground near the back of the truck depot lot. With an infrared illuminator directed at the Crows while using night vision optics, the eyes of each Crows shines back a bright white reflection. This is a fascinating phenomenon in some. nocturnal birds, notably owls. These birds have a layer at the back of the eye called the tapetum lucidum (literally ‘bright carpet’) that acts as a mirror & reflects light back through the retina. As a result, birds with a tapetum lucidum can see much better under low light conditions. The presence of a tapetum lucidum produces the bright white ‘eyeshine’ visible in the image below. The infrared illuminator causes zero disturbance for the Crows, yet allows a nice opportunity for documenting photos like this one!  

Photo gear used for this outing:

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 1DX MK II with Canon EF Telephoto Zoom 100-400mm f/4.5-5.6L IS II USM

ATN BinoX 4K 4-16x Day and Night Smart HD Binoculars with photo/video

SiOnyx Aurora Pro Digital Color Night Vision Optics

Follow us on Instagram: wintercrowroost

Follow us on YouTube: birdsoftheair1

Blog post and photos by Craig Gibson, 2020 Crow Patrol, Lawrence, MA