Even by February-in-Iowa standards, it was cold this morning! The coldest post-egg temperature ever recorded in Decorah happened on March 3, 2015, when the mercury dropped to -24F: a record! But we came pretty close today with a recorded temperature of -15F from about 5:00AM through about 7AM this morning. Eagles are well-suited to cold, but we’re still glad to see things warming up!
If you’re feeling chilly just watching – I know I am! – grab a warm drink and a blanket, put your feet up, and get ready for NestFlix! Curious about what’s inside DNF’s eggs right now? Take a peek here! https://www.raptorresource.org/2025/02/18/whats-inside-those-bald-eagle-eggs/
Decorah North Nest
February 18, 2025: DNF rolls her eggs
February 18, 2025: DNF peals, Mr. North takes over – https://youtu.be/MwP9P7usnBY?si=cjriKYVlF3qlDysO. I loved the soft pealing in this video. DNF incubated her eggs for an impressive 19 hours straight, from 4:34 PM on February 17 to 12:05 PM on February 18. She called a few times this morning, likely hoping for a break, but Mr. North didn’t arrive until the weather warmed up. While she seemed eager for relief, she was also reluctant to leave her cozy, warm nursery, taking a moment to stretch before finally flying off.
What’s going on with Mr. North? He seems to enjoy his time on the eggs and often hesitates to leave when DNF returns for her shift. Larger female eagles have more body mass, which helps them retain heat better due to a smaller surface area-to-volume ratio. That’s why they almost always take the colder night shifts and endure extreme cold spells. When DNF began incubating, wind chills were around -21°F, dropping to a frigid -32°F before warming back up to -12°F by the time Mr. North took over.
The magnificent Mr. North!
February 18, 2025: DNF rolls her eggs – https://youtu.be/Y_-mwvTzfiQ. We’ve talked about embryo formation before, but this is also a crucial time for membrane development. The chorioallantoic membrane (CAM) begins forming early in embryonic development and – much like the mammalian placenta – plays a vital role in facilitating gas and calcium exchange between the growing embryo and the outside world. Part of the embryo’s network of blood vessels lies outside its body and runs under the eggshell, collecting oxygen and calcium and releasing carbon dioxide.
Regular egg rolling is essential. Without it, the CAM and developing embryo can stick to the eggshell, leading to serious injury or even death. As of this roundup, Mr. North and DNF had rolled or footed their eggs seven times today.
February 16, 2025: Pheasant for breakfast
February 16, 2025: DNF arrives followed by a sub, pheasant for breakfast – https://youtu.be/8d4zcB7p5as?si=m0ULmtWiMz58gr5f. The video opens with Mr. North on the nest. He begins to vocalize and gets up quickly. At seven seconds, we get a view from outside the nest. DNF is coming in with a subadult in hot pursuit! Slow the video down to see it clearly or stop t 1:13 for an extremely cool look at all three eagles! The sub-adult peels off and DNF lands in the nest, still protesting the intrusion. At 4:01, Mr. flies out across the field and downstream. We get a nice look at the eggs as DNF breakfasts on pheasant before carefully settling back over the eggs at 7:19. Look for a nice view of the two eggs at 7:25.
Xcel Energy Fort St. Vrain Eagles
February 17, 2025: Ma Sleeps in Nest-Pa Kicks Intruder Out-Two Matings Back to Back – https://youtu.be/_zQ_SE-srC8?si=PF7GUPC4MR9RA76W. This is an interesting development! Chickiedee writes: “Ma makes an early morning visit to the nest to sleep the rest of the night. She and Pa return later in the morning. Late afternoon a subadult attempts to join Pa in the nest but he pushes the intruder out promptly. Ma arrives shortly afterwards, having apparently heard Pa’s warning vocals. They remain watchful. Then when it seems ok, Pa gets lovestruck for Ma. It looks like a very successful mating to me. Good job, Pa! After the infrared cam light turns on at dusk-30, Pa mounts Ma again for another round of mating. Afterwards, Ma takes off. Pa will soon follow.”
February 17, 2025: Pa brings fresh materials to the nest. Does Ma’s sojourn on the nest last night signal in earlier egg?
Ma FSV used to lay eggs in mid-February, but she switched to late-February/early March after accepting new Pa has a mate. However, gravid eagles often sleep in or near the nest. Will we get an early egg here, too? Stay tuned!
February 17, 2025: Uninvited guest chased off – https://youtu.be/Dlw9nQ4Y9d8?si=3T2lQS5k-o1LxIyJ. What part of ‘No’ don’t you understand? Pa chases a young adult eagle away from the nest.
Hear all the geese in the background? Like the North nest, the Fort St. Vrain nest is on a locally important migratory corridor and biome, which means we see a lot of visitors here. We should see their frequency diminish as the breeding season deepens and eagles shift northwards or to higher latitudes.
The Raptor Resource Project