Hanover Bald Eagle Blog # 11 - 2022
March 28, 2022
In partnership with Pennsylvania Game Commission and Comcast Business .
Written by Zoey Greenberg • In Partnership with Comcast Business and Pennsylvania Game Commission • Powered by HDOnTap
As of today there are two healthy little eaglets in the nest! They hatched on March 22nd and March 23, just 24 hours apart. Both have been feeding well and getting along in the nest. You'll notice peeps coming from the little ones as they learn how to communicate their needs.
Animals, including humans, communicate with each other using both verbal and nonverbal cues. Our pets demonstrate this every day — the dog barks and whines, but she also puts her head between her paws when she’s done something naughty. The cat meows and hisses, and also sits by the door when she’s ready to explore. My grandma’s African gray parrot says “cracker” when he wants a cracker, sings along with French music in nearly perfect pitch, and knocks over my coffee cup if I stop scratching his head. He has a lot of feelings and knows how to express them.
Animal’s communicate to express frustration, interest in prospective mates, to frighten off other animals, to call for assistance, to warn family members of danger, to express needs (for example a chick using a begging call when hungry), and so much more. The Hanover eagles have already demonstrated classic bald eagle vocalizations this season, including territorial peal calls and hic calls which are a staccato-sounding call, emitted when the eagles circle their nest from above.
Embed video of the intrusion event from 2019, 5 min. 33 seconds:
Intrusion event at the Hanover nest, 2019. Note vocalizations and body posturing.
To our ears, bald eagles are notably vocal, especially in situations like the one above. However, there are noisier eagles out there. The African Fish Eagle, which shares a genus with the bald eagle, has the Latin name Haliaeetus vocifer, meaning, literally, “noisy sea-eagle.” They live in sub-Saharan Africa, and, as mentioned in Keith Bildstein’s Raptors: The Curious Nature of Diurnal Birds of Prey, pairs are known to “begin their day in duet, both inside and outside of the breeding season, and subsequently respond in kind to their neighbors…vocal conflicts can continue for most of the day” (71).
Eagles also communicate in nonverbal ways. For example, when great-horned owls or intruder eagles threaten the nest, the Hanover eagles raise their hackles, which are feathers situated on the back of the head. Raised hackles serve as a sign of aggravation towards whomever the eagles are peeved at. We also see this behavior during tussles over food, and between siblings in the nest.
Other nonverbal cues signal a relaxed state, such as when birds fluff up their feathers and tuck a leg into their body. The tucking method also preserves body heat by keeping bare appendages protected from cool air. Birds do this when they sleep, burrowing their beak into their feathers for warmth.
Birds may fluff their feathers during courtship displays, while vocalizing, or as they are being preened by another bird. My grandma’s parrot fluffs up right before he attacks an unsuspecting ankle or shreds a couch.
Like I said, lots of feelings.
As you watch birds, read their body language. You might be amazed at what you can discover. And remember, they are watching us too. In Jon Young’s book What the Robin Knows, he discusses how our body language impacts our likelihood of seeing wildlife. If we act relaxed and casual, we will see more. If we are brisk and tense, animals notice, and avoid us. Birds like robins and juncos emit alarm calls when they suspect danger, and other animals listen to their assessments. One call used by robins is referred to as the narrowband distress call, or seet call, and functions as an alert to other robins that an aerial predator is nearby. Interestingly, this call seems to play off the hearing limitations of diurnal raptors. It’s a notably high pitched, thin call that is difficult for hunting raptors to triangulate. A robin can emit this call and remain relatively safe, while simultaneously alerting other robins to the presence of the hunter. Listen to the seet call here, under the name “alarm call.”
Hopefully we will soon have the privilege of hearing the Hanover chicks communicate with their parents through cheeping calls, which signal hunger. At four weeks old the chicks begin using wail, peal, and chatter calls, three vocalizations specific to nesting young.
Keep your ears open for the first conversation between the Hanover parents and their young.
Fun Fact
Ospreys vocalize to each other while soaring through thick clouds along their migration routes, presumably to keep the flock together. Traveling in a flock allows osprey to more easily spot thermals that offer lift and help them save energy.
Sources
Bildstein, Keith. (2017). Raptors: The Curious Nature of Diurnal Birds of Prey. Cornell University Press.
Buehler, D. A. (2020). Bald Eagle (Haliaeetus leucocephalus), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.baleag.01
Young, Jon. (2013). What the Robin Knows. Mariner Books.
Written by Zoey Greenberg
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