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How much does N2B weigh? An answer and four videos!

November 17, 2019 RaptorResource

How much does N2B weigh? We have an answer and four videos for your Sunday night! I always love seeing Mom and DM2, and both Flyway videos are spectacular. Thanks to our camera operators and videomakers for finding and sharing such special moments and to you for watching and caring!

Decorah Eagles

November 17, 2019: DM2 and Mom at N2B

11/17/19: 8am nestorations – https://youtu.be/6q8cxShptqc. While we see activity throughout the video, my favorite section started when Mom flew in at 5:58 with a curved and very wonky stick! She tried to snap twigs off, but the stick bent and moved instead of snapping. Once she finally got it prepared, DM2 took an interest and moved in. At 7:34, the two of them both start working on the stick, leading to a tug-o-stick around 7:40. Mom gives it all up at about 9:03 and walks up the Skywalk, leaving DM2 to nestorate to his heart’s content. At 9:49, we get a really nice side view of the nest as DM2 seems to finally get the stick under control! This video by Arlene Beech has a lot of the same footage but includes a nice early morning breakfish.

How big is N2B right now? It measures roughly 6×7 and is about 6.5 feet high. Its total volume is about 65 feet (this is a little rough to calculate, since it approximates a cone but isn’t quite as neat as the mathematical formula here: https://keisan.casio.com/exec/system/15374075343333). Since it is made from oak, maple, and cottonwood branches, we calculate the average weight at 40 pounds per cubic foot, which yields a weight of 2600 pounds. However, the nest isn’t made of solid wood. The eagles weave branches together in a rough spiral pattern and N2B has spaces, albeit tightly packed ones. I cast around a bit for a way to determine this unmeasurable space and finally decided to use the Fibonacci ratio of 61.8%. This number, which is also referred to as the golden ratio, or the golden mean, turns up quite a bit in natural series, especially ones that involve spirals. This yields an estimated weight of 1,606 pounds, or a little under a ton – a lot less than 2600 but still something to think about when you are hanging below it!

Mississippi Flyway

November 17, 2019: Eagles on the Flyway

11/17/19 – Bald eagles gather around prey on the Mississippi River Flyway: https://youtu.be/V6_EFNRnbkA. This is a cool video! Bald eagles gather around what appears to be a dead Tundra swan. We don’t know whether they killed it or found it dead, although I’m guessing the latter. Why? Eagles are capable of killing a swan, but we’ve never seen them do so despite a huge number of swans. Pool Seven has also experienced waterfowl die-offs due to a trematode parasite carried by snails. It doesn’t affect raptors, but it does affect lesser scaup, coots, and other waterfowl, including tundra swans. Either way, the mix of eagles includes adults, sub-adults ranging from maybe 2.5 to 4.5 years old, and what looks like a juvenile. Look for a fascinating mix of plumage and a lot of jostling around as everyone tries to get a bite!

It can be hard to watch predators, even predators we really love, eat something like a Tundra swan. But I take comfort that nothing ever goes to waste. The death of the swan will give life to the eagles eating it, and so the circle of life goes around.

11/17/19: Close-up of juvenile bald eagle – https://youtu.be/0sIagZNkBb4. This is just cool! The eagle is sitting on the solar panel pole and we get a really nice look at it. Judging from the PS on the panel, this is a popular perch!