September 7, 2022: D27 and D36
D27: Home for the Fall!
In late July, D27 sent a postcard from just inside Manitoba: the farthest north that any of our Decorah eagles have traveled. She started her fall migration on August 10, traveling 79.1 miles SWS to an unnamed lake 58 miles ENE of Sachiago Lake. After several short flights of 30 or so miles, she flew 145 miles south between August 16 and August 18, and an incredible 338 miles between August 19 and August 22! She flew within 3.9 miles of her natal nest on August 29th and is currently hanging out in the Postville area, about 18 miles south. Since January 1 of this year, she has traveled an incredible 3,190 miles. That is a lot of wind beneath her wings!
Changes in Latitude, Changes in Daylight Length
I got curious about her daylight length profile. We know that daylight length pulls a lot of strings in a bird’s body, and we also know that D27’s daylight length changes quite a bit with the seasons and her latitude.
- Between November 15, 2021 through February 1, 2022, D27 experienced less than 10 hours of daylight per day.
- D27 was above the 50th parallel from June 1 though August 19. She averaged 16 hours and 13 minutes of daylight while she was there: an increase of 39% over her solar minimum. Her solar maximum occurred on June 23 when she experienced 16 hours and 55 minutes of day.
- D27 did not experience true night from June 1 through August 9. Between August 9 and August 19, true night went from 1 minute, 3 seconds to 3 minutes, 33 seconds.
- Changes in latitude might mean changes in attitude, but they also mean changes in daylight length! Between August 12 and August 22, D27 lost over an hour of daylight as she moved from the 54th parallel to the 45th parallel. The days will remain shorter in Decorah until the fall equinox on Thursday, September 22.
D36: The Iowa Staycation Continues!
How is D36 doing? Our little homebody is continuing his Iowa staycation, wandering back and forth between the Turkey River and Ten-Mile Creek. Do subadult male eagles travel less than their female counterparts? It’s tough to say. I checked D36’s logs and he’s traveled 2096 miles so far this year: quite a bit less than older half-sibling D27! However, he traveled more miles overall in his first two years compared to hers.
- From September 1, 2020 to September 1, 2022, D36 traveled about 7,950 miles.
- From September 1, 2017 to September 1, 2019, D27 traveled about 7,830 miles. She’s flown an incredible 19,199 miles since we started tracking her on August 9 of 2017: far more than I’ve flown in my lifetime!
Thanks so much for the postcards, eagles! Fly high and stay fierce – winter is just around the corner and it might be cold and snowy this year!
A thousand thanks to Brett Mandernack and the staff of Eagle Valley for sharing their maps, expertise, and data with us, and to the Kohler company for supporting our bald eagle tracking program! To follow the travels of any of the eagles we’ve tracked, please visit our interactive maps at https://www.raptorresource.org/learning-tools/eagle-map/.
The Raptor Resource Project