Followers had a lot of questions about eaglet DH1 and DH2. Why did DH1 die? Are HD and HM first-time parents? What did the eagles do with DH1? Here’s what we know.
Why did DH1 die?
DH1 hatched at 4:10 AM on April 5th and died some time between about 7 PM and 12:20 AM. The day was cold and rainy, the eagles tucked a large dead trout into the egg cup, and DH1 was not fed in its first day of life. While eaglets should be able to go about 24 hours without a feeding following hatch, the large, cold fish and general weather conditions placed high energy demands on the hatchling. DH1 most likely died of hypothermia, with lack of food a probable contributing factor. Note: DH1 seemed quite healthy – even feisty! – on the day of April 5th. We have no reason to think DH1 died of avian influenza and do not think it was taloned. Followers asked if the flopping fish could have injured DH1. Not that we saw, but we can’t rule injury out as another contributing factor in DH1’s death.
What do eagle parents do with an eaglet’s body?
In general, carcasses are either buried or consumed. If parents don’t eat the carcass or feed it to their young, it is eventually buried under grass and nesting materials as it decomposes. In this case, HD and HM left DH1 in the nest.
Eagle parents often larder or cache food in their nests, which means that eagle nests tend to be full of remains, including skulls, spinal columns, vertebra, turtle shells, opercular bones, and so much more! You can take a look at some of them here: https://www.raptorresource.org/2017/09/11/whats-on-the-menu-at-fort-st-vrain/.
Are HD and HM feeding DH2?
Yes! Our volunteers are counting every bite, but you can also look to see if the eaglet has a crop, aka snack pack. This muscular pouch in a bird’s neck functions as a storage place for food. If it’s swollen, DH2 has been fed. Pooping is another good sign!
April 11, 2023: DH2 sports a little crop!
Are HD and HM first-time parents?
We believe they are. HD and HM arrived in March of 2022, although they didn’t start spending a lot of time on N1 until April. Followers might remember that HD especially had a hard time figuring out copulation, although it was adorable once he finally did! He also flew away from the nest at his first sight of the egg (although he came back quickly), and both HM and HD seemed to struggle with feeding. Watchers might remember peregrine falcon Zooey’s first year in 2021. While Zooey had the will to feed, she didn’t understand how to accomplish it and, in her first few days as a new mother, sometimes dropped whole birds on her hapless hatchlings. Both HM and HD behaved very similarly with DH1.
There is so much to think about here! Some researchers believe that eagles can form bonds on their summering grounds that carry over into newly-established nesting territories. That idea dovetails with some of the behavior we’ve seen on the Flyway, and the behavior of a pair of adults that I’ve been watching on a non-breeding territory this winter. Perhaps HD and HM arrived with their bond already intact. Bonds have to start somewhere!
This year has also been unusual because both eagles appear to be inexperienced. Usually we see either one inexperienced and one experienced partner (Mom and Dad in 2008, DM2 and Mom in 2019, DNF and Mr. North in 2019, possibly Mr. North and Mrs. North in 2016) or two experienced partners. This is the first time we’ve seen two partners who appear to be inexperienced.
Instinct versus learned behavior versus reflexive actions
When is it instinct – an innate, typically fixed pattern of behavior in animals in response to certain stimuli – versus reflex – involuntary movements or actions – versus learned behavior – a behavior that an organism develops as a result of experience? It’s a complicated question with very fuzzy boundaries.
Instincts include behavior like copulation, nest-building, feeding, and flying. These are things that eagles feel compelled to do: behaviors that make human watchers wonder “How do they know they should do that?”.
Reflexes are involuntary actions that can’t easily be stopped or controlled: the doctor taps your knee and you jerk, something touches the center of an eagle’s footpad and it immediately grabs, an infant roots when the corner of its mouth is stroked.
Learned behavior is a behavior developed through experience, although the behavior is probably rooted in instinct. Let’s talk about feeding! Feeding is instinctive and prompted by a hatchling’s gape or peck in many species of birds. A hatchling eaglet opens its mouth and/or vocalizes, which prompts a parent to feed it. A baby gull instinctively pecks at a red spot on its mother’s beak, prompting a feeding – a two-step chain of instinctive behaviors! But learning plays a significant role in feeding and eagle parents get better at it as they repeat it. Feeding, copulation, and flying are all instinctive behaviors, but skill takes experience and learning.
People try to divide the world into neat categories, but instinct, reflex, and learning dovetail in really complex and fuzzy ways. Is an eagle curling its feet an instinctive response to a reflex that could crush eggs or eaglets? Is poop shooting reflexive or instinctual? Does a nesting eagle engage in life-long learning when it comes to the instinctive behavior of nest-building? We know that eagles build on instinct and get better at many tasks as they repeat them, but applying our discreet worldview to their entangled world might not be a helpful way to think about them. We’ll be writing more about that!