We were asked about eaglet growth and development during our explore.org Bird Week chat yesterday. Bald eagles spend about the first half of nest life – say, 35 to 40 days – gaining weight, growing limbs and feet, and growing and replacing feathers. In stage two – about 40 to 75 or 80 days – they begin preparing for life beyond the nest by building muscle, exploring their new wings, learning to unzip prey and feed themselves, and practicing their best eagle table manners: hissing, stealing, running, mantling, dominating, submitting, and – sometimes – sharing.
In the video above, younger eaglet DN16 – identifiable right now by its higher percentage of natal down to juvenile feathers – is feeding itself. Older sibling DN15 moves in for the steal, but DN16 doesn’t feel like sharing or submitting. It parries DN15’s attempted food steal with a peck and a bantle, eventually moving across the nest to evade DN15’s continued interest in dinner. DN15 makes one final attempt at a steal, but DN16 puts a quick end to it with a few decisive pecks! You can see the whole saga here: https://youtu.be/Q7vlHHg4x-E.
A Life-Long Lesson
What are DN15 and DN16 taking away from their in-nest interactions with one another and their parents? Juvenile and subadult eagles need to make a lot of snap judgements as they hunt, find, defend, lose, and steal food. How hungry am I? Are my opponents larger and/or more committed to this meal? Can I sneak in while everyone is fighting and fly away with the prize? But once they settle into married adult life, those same eagles need to hunt and share food with mates and young. As eagles move from post-fledge to mated adulthood, they acquire and practice a wide variety of finding, hunting, and stealing strategies that spring from their early experiences in the nest.
DN15 and DN16 are learning eagle table manners: stealing, dominating, submitting, and defending food by hissing, biting, pecking, and mantling. When DN16 made it clear that sharing wasn’t an option, DN15 stopped to avoid a serious and potentially injurious altercation over a meal it didn’t really need in the first place. Look for more growing and learning to take place as the tree-riffic two wingercize, trampoline, improve their unzipping and feeding skills, ‘play house’, and build the muscle, coordination, social skills, and adaptability they need for life beyond the nest!
Diction-aerie Word of The Day: Bantle
Bantle: A babylet mantle | ban·tle. DN15 doesn’t quite have the feathers it needs to mantle over its dinner. That doesn’t stop it from hunching over, trying to obscure its food, and making it clear that sharing isn’t allowed – a bantle, or babylet mantle!
50 States of Conservation
What can you do to help eagles and other wildlife? When it comes to habitat preservation, I recommend joining a local ‘Friends’ group: a group dedicated to conserving and improving land and water quality in your neighborhood, community, or region. It’s a wonderful way to support local habitat projects and meet other people who are concerned about conservation. Thanks to Pauline H. for suggesting the Bur Oak Land Trust: https://buroaklandtrust.org/. The Bur Oak Land Trust advances biodiversity in Eastern Iowa by protecting resilient landscapes, connecting people to nature, and protecting native habitat from destruction. Check them out, send recommendations from your community to [email protected], and help share the word that conservation is important everywhere! #50statesofconservation
Odds and Ends
What are feathers? What is molt? Curious about the two feather changes that eagles undergo in the first half of nest life? This blog is for you! https://www.raptorresource.org/2019/05/19/what-are-feathers-what-is-molt/
I listen to the podcast Snap Judgement and really enjoyed BirdZilla: A Canadian Love Story. I hope you like it as much as I did. Birds make a lot of snap judgements!