DN17 and DN18 turn 38 and 37 days old today and we’re getting asked about their likely sexes. We’ll be looking and listening for differences, but we wanted to address a couple of interesting factors when it comes to eaglet size and sex.
After about 30 days, the weights of the two sexes begin to diverge as females gain weight faster than males. Mark Stalmaster tells us that three major circumstances influence the relative sizes of nestmates: early hatchers are larger than late ones (hatch order), females outweigh males once eaglets reach about 30 days of life (sex), and eaglets may be larger in smaller broods (probably related to food abundance). So if one eaglet is female and the other is male, we might be seeing sex-linked size differences if both are standard examples of female and male eagles.
Given the food abundance in the North Valley, it is a little more likely that DN17 is female and DN18 is male. A large, multi-year study of Bald Eagles in Canada found that females represented 64% of first-hatched eggs and 33% of second-hatched eggs in years with abundant food, and 39% and 37% of first- and second-hatched eggs in lean years: i.e. females are rarer overall in lean years. Time – and vocalizations – will tell!
In Other News…
May 1, 2024: Hatch has started at the Dubuque County Courthouse!
In other news, hatch has started at the Dubuque Courthouse Peregrine Falcon nest: the first of our sites with a camera to hatch this year! Our next first hatch should happen at Great River Energy. We thought hatch might begin yesterday – 33 days after the penultimate or 4th egg, since Breezy laid five eggs this year, but five-egg clutches can be a little harder to forecast accurately. She was sitting pretty high this morning, which is often a sign of HIP or hatchlings, but I can’t see any shell or young. Dubuque Courthouse Falcons: https://www.youtube.com/live/cFtQqGanrX0?si=9qQHyfFh_Hd0WZOR | Great River Energy Falcons: https://www.raptorresource.org/birdcams/great-river-energy-falcons/.
Happy May Day, everyone! I hope you enjoy these videos as much as we did.
Decorah North Eagles
May 1, 2024: DN17 demonstrates wingercizing, standing tall – https://youtu.be/SUzxpCN7xPw?si=hO_NH0krwneof1M9. The video opens with DN18 and DN17 laying side by side in the nest. DN17 gets up, warbles, fiddles with nesting material and, at 1:03, demonstrates standing up tall! At 3:11, DN17 goes into a warble that turns to a winger as the eaglet spreads its wings – look at how long they are! – and feels the air.
May 1, 2024: DN18 feels the wind beneath its wings!
DN17 and DN18 are both a little unsteady on their feet, but they are learning in leaps and bounds! Their growth is slowing down but they are building muscle and coordination as they check and refine their pre-flight skills: standing, wingercizing, grabbing and holding with their feet, and – eventually – tearing their own food and bouncing around the nest. I picture their brains lighting up with new sensations and behaviors as they stand up tall, explore their wings, strengthen their muscles, and learn what to do with their feet and beaks. Flight school is a process: eagle nest school to eagle outdoor school to eagle college!
May 29, 2024: A delightful eaglet cuddle puddle!
April 29, 2024: DN17 & DN18 trying nestorations, picking at bones, tug-o-war – https://youtu.be/debXvlTR0iI?si=Smt6aWLfHLZ4lvbP. This video has a little bit of everything! The eagles play house, fiddle with a leg bone – look for closeups and delightful moments beginning at about 1:48 – stand up tall and warble, PS (4:12), and wingercize (7:15). I loved this look at the dynamic duo and their daily activities!
April 29, 2024: The Bone Collector! Then the fun begins! DN17 did its best to swallow it – https://youtu.be/5LFZ-8X-on8?si=E-i2O86NF1gtQfzL. The video opens with DN17 nibbling on the legbone from the video above. DN18 moves in for the steal at 27 seconds and nibbles on it before DN17 takes it back. The bones goes back and forth a few times – look for a wishbone tug-o-war at 1:08 – as both eaglets try to figure out how to eat it! At 2:34, DN17 almost has the bone down the hatch, but DN18 literally grabs it out of DN17’s mouth. DN17 tries again at 4:30 and 5:45, but can’t quite get it down the hatch!
Who needs fancy toys when you have a tasty old bone? Check the video at 6:04 and you’ll see DN17 practicing dinner prep and footwork as it grabs the bone with its foot and tries to tear with its beak and lever with its body.
April 30, 2024: How do I eat this thing? DN17 and DN18 nibble at a bone as they swap it back and forth.
April 28, 2024: DN17 with the steal and the mantle, but DNF says not so fast – https://youtu.be/OpaJBRYLDW8?si=eKofM0fY4bh1xpkU. Eagle table manners: hiss, steal, mantle, vocalize! A+, DN17! These skills will stand you well once you graduate to eagle college.
Trempealeau Eagles
May 1, 2024: TE2 and TE1 at Trempealeau
April 30, 2024: Breakfast by Mr. T – https://youtu.be/l6nuKoVb77U?si=0vgMvNjtpjpuZxbH. TE1 and TE2 are 28 and 24 days old – just two weeks or so younger than DN17 and DN18. But look at the size, feathers, and skill difference between the eaglets! Mr. T, almost certainly a first-time father based on his behavior, is feeding his young for the third time that we know – and the second time in a day. I liked this whole video, but I really enjoyed him seeming to watch TE1 after 13:30. Instinct is weird!
The Raptor Resource Project