Date: 8/17/25 12:59 pm From: 'PAUL ROBERTS' via Arlington Birds <arlingtonbirds...> Subject: [Arlington Birds] Status of Arlington's Eagles
Hi, So far so good. (Knock on wood.) KZ and FAE (Female Adult Eagle), nesting on the Mystic Lakes, hatched and fledged three eaglets in 2025: 75/C, the largest and almost certainly the oldest, and a female; 76/C, likely second-hatched and male, but conceivably a small female; and 77/C, last hatched, first fledged, and the smallest and most aggressive of the three. FAE has been an absolutely incredible mother. Based on her behavior, I'm inclined to think that she is as old or older than KZ, and likely previously mated, but she is unbanded, so her past has "passed." She clearly does not trust/like people being close to her. She is much more wary of being close to people than KZ, who was previously mated with MK, who regrettably had no fear of people. This year FAE was incredibly regular on incubating the eggs and expecting KZ to relieve her of those duties within minutes of dawn. She would quickly head off a distance to void, hunt, and relax for several hours. Once the eggs started to hatch, she remained very close to the nest at all times. KZ is a fantastic mate. He provided food to FAE, but she often fished for herself. He patrolled the lakes intensely, especially after FAE began laying. He tolerated juveniles and yearlings on the upper lake and forebays as long as they kept a respectful distance. However, any bird appearing close to adult plumage was aggressively ushered out of the area. Several times I was shocked to see him intercepting whitish-headed birds as far north of the Upper Forebay as I could see, conceivably close to Horn Pond, and driving them farther away. KZ is ten years old this year, probably his best year ever. I've been critical of him for taking the easiest prey, such as adult herring returning south over the dam, when they are exposed on the spillway. He did that earlier this year, but the dam has been one dry for weeks with no fish going over (including no eaglets imitating Dad's inclinations.) Instead, as the kids reached maximum growth rate beginning around 5 weeks of age, he started delivering huge fish to the nest, some of the largest fish I've ever seen pulled out of the lakes. Some were so heavy that KZ could barely carry them higher than a few feet above the water, and he had to stop and rest in the gnarly trees before trying to lift the meal up 50+ feet into the nest. (KZ probably weighs about 8 lbs.) Several times in the late winter he took fish too heavy for him or FAE to lift off the ice, so he began eating the fish on the ice and then gave way to his mate to eat to her heart's content before carrying the remains to a more secluded spot to finish it off. Feeding three eaglets is very challenging, but KZ and FAE have given lots of fish, along with squirrels, rabbits, and a raccoon or two to their kids. FAE ensured that the smallest kid was adequately fed, tearing up prey and giving it to him directly after both adults began tossing the fish directly into the nest.. Even after the kids branched and then fledged, I was surprised to see FAE and KZ still deliver most of the food to the nest. Normally one would expect the adults to take prey to perches away from the nest, and eventually put some on the ground, to encourage the search and hunting instincts of the kids. The kids know EVERYWHERE where Mom and Dad like to perch. They've gone to those places frequently, begging loudly for food. FAE and KZ have had enough, It is clear that both have communicated to the kids that they should not go begging to KZ's "man-cave", or to FAE's favorite perches on the opposite end of the lakes. The adults are tired of all that begging, so the kids are not nearly as vocal as they were. FAE also is not seen nearly as much, as she is molting heavily and appears to prefer remaining out of sight. She has delivered very few fish, and tiny ones at that, recently. (She looks like she was awakened in the middle of the night while sleeping in her clothes.) Unlike earlier, she has been seen on Mass Ave in Arlington and Spy Pond. KZ has been seen lounging at Horn Pond. Two days ago we had all three kids soaring together briefly, but most of the time we see only one or two, usually 75/C and 76/C, and they often are well hidden, seen briefly in distant flight They are now begging much less than has been the case. Today 75/C was seen striking the water in several apparent fishing attempts. The kids have scavenged leftovers deposited by Mom or Dad, and are apparently fed occasionally by KZ, usually late in the day. With the drought, there is no water running over the dam so no herring or other fry providing easy pickings for the kids or photographers. The past ten days have been some of the quietest of the year. There are rare occasions when two or three might be seen flying, occasionally soaring, in the distance, Within the next two or three weeks, the degrees of separation should increase significantly. 77/C is now rarely seen, and more far-ranging. 75/C and 76/C will increase that degree of separation and distance, looking for other juveniles for company, and hoping the strangers know where and when to find free, easy food. As they melt into the woods and ponds of eastern Massachusetts, they might disperse to the mid-Atlantic states, like KZ's earliest kids, but it seems increasingly likely that they might just hang out with other juveniles and yearlings at some new fishing holes in eastern Massachusetts. They meet and socialize with other youngsters and are tolerated by other adults. They have about two years of good will before they might be seen as territorial or social threats. Data suggests that with global warming "local" eagles often don't feel the need to go south. They use the winter to explore their natal areas, where they ultimately will likely attempt to nest. FAE will finish her molt and start ranging a bit more for a few months. KZ needs to go through his molt after he is done with the heavy load of feeding the kids. The two adults need several months R&R, often off-lakes, before they think of repairing the nest, or what they are going to do for next year. Birds this large, – that require 3-5 years to mature physically – have distinctive personalities. I think FAE is on the socially conservative side, probably raised away from regular close contact with humans. I think she is an incredibly smart and capable parent. KZ's tenth year has shown him to be more mature and apparently a better provider than ever before. He's fledged ten eagles on the Mystics and never done a better job than he has this year. Last year two eaglets died within a week of fledging, and the first fledgling (91/C) incurred a serious injury but was rehabbed and released. Two notes. In 2020 KZ was the territorial adult male on the Mystic Lakes and MK, a year younger, his mate. After they built the nest, MK hatched at least one chick. That spring, while MK was incubating or brooding, KZ was challenged by at least six different adult male Bald Eagles, ultimately losing twice to Z74, an adult from New York State. Z74 stole MK's first nestling from the nest and killed it, and then chased KZ around and around the lakes, causing KZ to roll over in defense and lock talons with his pursuer. The birds tumbled from the sky, and only Z74 emerged from beneath the horizon. He took possession of the lakes and theoretically MK, who refused to copulate with or feed Z74. (see "Eagle Wars," pp.4-11, Massachusetts Wildlife, No.2, 2020.) I had never read of such competition between males when the female was already incubating eggs, but it made some sense in that the female incubating was "held captive," because if she abandoned the eggs she would lose the clutch and probably the entire breeding season. I did extensive research and contacted many leading authorities on eagles. No one reported observing similar behavior in their experience.) Second, I would caution readers to seriously question instances where they see adult eagles locking talons and tumbling. In my research and experience, this is almost always agonistic behavior, i.e., fighting usually but not always between two birds of the same gender. (I have seen the larger female come to the "rescue" of her mate against a larger male foe.) Tail chasing, talon dropping, and even talon locking can be valuable "training" for immature birds, practicing for eventual defense of territories and mates in their adulthood. Very rarely do adult mates ever lock talons with potential mates in breeding displays, if at all. Best, Paul Paul M. Roberts Medford, MA <phawk254...>
