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Juan Lacruz via Wikimedia Commons // CC BY-SA 2.5
Juan Lacruz via Wikimedia Commons // CC BY-SA 2.5

It's Not Just Your Grandparents—Older Eagles Leave Early Too

Juan Lacruz via Wikimedia Commons // CC BY-SA 2.5
Juan Lacruz via Wikimedia Commons // CC BY-SA 2.5

Kids these days have it so easy. Scientists say young golden eagles display a laissez-faire attitude toward migration, leaving later and waiting for good weather before setting out, while their older relatives perform the avian equivalent of walking to school uphill both ways in the snow. The researchers published their findings in The Auk: Ornithological Advances.

With beautiful russet feathers, a wingspan up to 7.5 feet, and a sensational diving speed, the golden eagle (Aquila chrysaetos) is an impressive sight at any age. They're chiller than their notoriously daring Scandinavian cousins, which carry off bear cubs [PDF] and attack reindeer and wolves.

Juan Lacruz via Wikimedia Commons // CC BY-SA 2.5

 
A. chrysaetos populations in eastern North America spend their summers mating and raising chicks in Quebec, Ontario, and Labrador, then head south to the Appalachian Mountains for the winter.

Ornithologists wondered how the birds’ lengthy trips were affected by environmental conditions like sunlight and wind speed. To find out, they captured 90 eagles, outfitted each one with a light backpack containing a GPS tracker, recorded the bird’s approximate age, then let them go. The birds and their backpacks flew back and forth for years, transmitting information all the while.

Combining the GPS data with local meteorological records revealed some interesting patterns. All the birds flew both farther and faster when tailwinds were in their favor. But when the weather went bad, a split emerged along age lines. Older birds hit the air anyway to make sure they arrived at their nesting sites in time to breed. But younger birds apparently felt no need to battle the elements and waited until clearer days arrived.

Paper co-author Todd Katzner of the U.S. Geological Survey says the two groups’ divergent travel styles are a product of their different needs. Old birds are slower and have fewer breeding seasons remaining; they don’t have time to waste hanging around like the whippersnappers do, so they get going right away. “Younger eagles just need to survive the summer,” Katzner said in a press statement, “so they can be choosy about when they travel north and only migrate when conditions are really ideal for fast soaring flight.”

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Animals
Where Do Birds Get Their Songs?
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iStock

Birds display some of the most impressive vocal abilities in the animal kingdom. They can be heard across great distances, mimic human speech, and even sing using distinct dialects and syntax. The most complex songs take some practice to learn, but as TED-Ed explains, the urge to sing is woven into songbirds' DNA.

Like humans, baby birds learn to communicate from their parents. Adult zebra finches will even speak in the equivalent of "baby talk" when teaching chicks their songs. After hearing the same expressions repeated so many times and trying them out firsthand, the offspring are able to use the same songs as adults.

But nurture isn't the only factor driving this behavior. Even when they grow up without any parents teaching them how to vocalize, birds will start singing on their own. These innate songs are less refined than the ones that are taught, but when they're passed down through multiple generations and shaped over time, they start to sound similar to the learned songs sung by other members of their species.

This suggests that the drive to sing as well as the specific structures of the songs themselves have been ingrained in the animals' genetic code by evolution. You can watch the full story from TED-Ed below, then head over here for a sample of the diverse songs produced by birds.

[h/t TED-Ed]

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Animals
Watch the First-Ever Footage of a Baby Dumbo Octopus
NOAA, Wikimedia Commons // Public Domain
NOAA, Wikimedia Commons // Public Domain

Dumbo octopuses are named for the elephant-ear-like fins they use to navigate the deep sea, but until recently, when and how they developed those floppy appendages were a mystery. Now, for the first time, researchers have caught a newborn Dumbo octopus on tape. As reported in the journal Current Biology, they discovered that the creatures are equipped with the fins from the moment they hatch.

Study co-author Tim Shank, a researcher at the Woods Hole Oceanographic Institution in Massachusetts, spotted the octopus in 2005. During a research expedition in the North Atlantic, one of the remotely operated vehicles he was working with collected several coral branches with something strange attached to them. It looked like a bunch of sandy-colored golf balls at first, but then he realized it was an egg sac.

He and his fellow researchers eventually classified the hatchling that emerged as a member of the genus Grimpoteuthis. In other words, it was a Dumbo octopus, though they couldn't determine the exact species. But you wouldn't need a biology degree to spot its resemblance to Disney's famous elephant, as you can see in the video below.

The octopus hatched with a set of functional fins that allowed it to swim around and hunt right away, and an MRI scan revealed fully-developed internal organs and a complex nervous system. As the researchers wrote in their study, Dumbo octopuses enter the world as "competent juveniles" ready to jump straight into adult life.

Grimpoteuthis spends its life in the deep ocean, which makes it difficult to study. Scientists hope the newly-reported findings will make it easier to identify Grimpoteuthis eggs and hatchlings for future research.

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