Date: 1/10/25 6:55 am From: 'PAUL ROBERTS' via Arlington Birds <arlingtonbirds...> Subject: [Arlington Birds] Mystic Lakes Common Megansers
This morning I estimated there were at least 1300 Common Mergansers on the Lower Mystic Lake between 7 and 8 a.m. This is about twice the maximum count I have ever seen there, but I have never seen so many ducks on the Mystic Lakes or so many Common Mergansers anywhere. At dawn I had small wave after wave flying from out of the dark over the Upper Lake to the Lower Lake. Several hundreds at least. Then another series of waves. At this point I could not see anything on the lower lake due to low light. Then I had what I estimated at 300-400 Mergansers climbing into the sky over the lower lake, a spectacular sight for someone who loves mergansers. As the sun began to rise over the eastern "ridge" I saw hundreds upon hundreds on the south end of thee lower lake. I estimated by tens and came up with over 1100 mergansers, which I don't think included the flocks I had seen lifting off the lower lake minutes earlier. Then wave after wave from the north again. I had a female subadult Bald Eagle fly out over the middle of the lower lake and was shocked that none of the mergansers lifted off to avoid being caught by the eagle. The eagle circled and dropped down on the water 5-6 times, obviously going after a fish, but never flushing any of the mergansers. The eagle didn't hit the water at all that I saw, but I might have missed it in the poor light, trying to photograph the eagle, because a much larger subadult came flying in and pursued the first eagle as though the second had seen the first catch a fish. Whatever, both eagles perched in the far distance. The number of mergansers continued to increase, so I estimated by 20s, and came up with over 1300 on the water at that time. I could have waked across the lower lake on the backs of Mergansers if I was just a few hundred pounds lighter. I did a second estimate, using a camera with a 125X lens to make my estimates). Over 1300 again. Notably many more immature or female Commons than I have been seeing. There were number of Hooded Mergansers around, but in small groups, and often courting, with males grunting loudly and displaying in the water while my fingers were increasingly numb and my camera balked at single-digit wind chills for over an hour. I am at the lakes daily early in the morning and this was by far more ducks than I have ever seen there. I am accustomed to the vicissitudes of dropping temps and ice ups on nearby ponds, lakes, and streams. On milder days when shallower bodies frequently ice up over night and open up slightly or more during the day, merge and other divers roost for the night on the deeper, more open waters of the lakes. The Forebay is almost completely iced over, but this week the entire upper and lower lakes have been wide open, while the river is increasingly freezing overnight and most nearby bodies freeze up or are close to freezing overnight, so divers and dabblers seek refuge on the Mystic Lakes, where the strong winds and the effects of the dam tend to keep the deep lakes open much longer/later in the season. Thus to see something like this, the day that you go, the overnight temperatures, the winds, the specific time of day, all affect the behavior of the ducks, so each day, each hour, can be and usually are different. But today was REALLY different. I've never seen it like this. Never seen so many gorgeous Common Mergansers at one time. I don't expect to see nearly that many tomorrow. Historically, as freeze-up lengthens, they seek out deep fresh water bodies farther south and do not return until spring migration staging. Best, Paul Paul M. Roberts Medford, MA <phawk254...>
