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Behind them lay the makeshift campgrounds where they had spent months living rough, waiting for the right moment to climb the six-metre, razorwire fence lying between them and their dream of making it to Europe. In front of them lay an immaculately groomed golf course complete with white-clad golfers teeing off.

The two radically different realities, just metres apart, was what greeted a dozen or so migrants caught on the triple fence that marks the border between Spain’s north African enclave of Melilla and Morocco on Wednesday. After 200 had tried to scale the fence, Spain’s interior ministry said 20 people had made it to the enclave and another 70 remained perched on top of the fence for several hours.

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Avian Migration: The Ultimate Red-Eye Flight

Birds that migrate at night enter a state of sleepless mania and gorge on foods by day, behaviors mediated by their biological clocks

Paul Bartell, Ashli Moore

Migration requires dramatic seasonal changes in behavior and physiology, and these changes must be timed appropriately for successful migration.

In late summer after nestlings fledge, birds begin to molt, replacing their ratty old feathers with sleek new ones. They also begin to gorge themselves. The flurry of activity around this time of year reflects this frantic, single-minded pursuit of food. The birds’ hyperphagia, or excessive eating, is accompanied by great changes in body weight and composition. The birds get very fat—and then they are gone, en route to their wintering grounds on a journey of several weeks.

They spend the winter in warmer climates, where resources are sufficient for survival. In late winter, they grow new feathers again; afteward, there’s another weeks-long period of hyperphagia. When the days get longer and the temperature is just right, they’re off again, migrating to summer breeding grounds.

Upon arrival, males establish territories. Pairs form. Nests are built. Soon, eggs are incubating, then hatching, and parents devote almost all of their energy to feeding chicks. If time permits, parents may mate again and have another clutch.

Then, the cycle repeats…

(read more: American Scientist)

illustrations: Barbara Aulicino and Emma Scurnick

"…these Fowls, which make such Changes, and observe their Seasons, to pass and repass between this and the Moon"

So says the 1703-(ish) pamphlet Whence Come the Stork, and the Turtle, the Crane, and the Swallow, authored by an unnamed “Person of Learning and Piety” which turned out to be Harvard lecturer Charles Morton, a man who, despite his most valiant efforts at performing science, went down in history for giving us one of the most stunningly ridiculous theories of where birds went during winter: our moon. 

Morton based that lunarcy on the newly-developed theory of gravity, surmising that migrating birds took to the highest skies so they could escape the pull of Earth, and coast easy on their 200,000+ mile trip to the moon’s lakes. Oh yeah, I forgot to mention that Morton and his contemporaries thought that the moon was covered in vegetation and liquid water, although they never did explain the resulting problem of gray plants and gray water and gray everything.

If you’re thinking to yourself “this sounds bonkers,” that’s because it is bonkers. But until just a few centuries ago, lots of people were certain that birds, despite their obvious ability to fly, definitely couldn’t fly thousands of miles every season. That was just too much. Or if their theories did allow for birds to make long trips to escape the cold, the destinations and purposes were equally batty (flight-related pun unintended).

Let’s take a look at a few of the wackiest theories:

Aristotle’s theory of transmutation: This great Greek thinker, who lived during the 4th century BC, noticed that when the red-breasted Redstart disappeared, the red-breasted Robin showed up. They look similar enough, so naturally one turned into the other, right? Amazingly, the biological theory of transmutation held on in one form or another until Charles Darwin’s time. 

Sleeping with the fishes: How did Aristotle and his contemporaries explain the many birds that disappeared in winter and did NOT get replaced by similar species? He proposed that swallows and other birds buried themselves in the mud, frozen solid until the spring thaw. Aristotle was so influential in his incorrectness that this idea lasted until at least the 16th century, demonstrated by the above woodblock print showing fishermen harvesting swallows from a frozen lake, made in 1555 by Swedish bishop Olaus Magnus. It might be a crazy idea for birds, but thanks to antifreeze-infused blood, some species of frogs can actually pull this off

Homer’s warrior cranes: Aristotle wasn’t the only Greek with goofy ideas. In Homer’s Iliad, he writes of cranes flying to “the world’s end” to battle armies of mythical Pygmy men (rather disparagingly, European explorers gave various tribes of short-statured native people the name “Pygmy” in the 19th century). Over the millennia, the tale of goat-riding Pygmies battling hordes of cranes spread popped up throughout Eurasia, from Aesop’s fables to Pliny the Elder. At least they got the migration part right?

Geese don’t grow on trees… heck, they don’t even sit in ‘em: Since Barnacle geese (Branta leucopsis) were never seen breeding in their European coastal habitats, their origin story was left to the sea. Certain barnacles common in the area had similar coloring and often extended feather-like feeding appendages called cirri.

Since these barnacles grew on driftwood, it was thought that somewhere there existed trees full of budding gooseberries that would drop baby birds into the water each spring. This myth was so common, that some Catholic bishops declared the birds, being made of seafood and not poultry, acceptable for the dinner table during Lent.

Of course, now we know that all of these birds migrate with seasons, accomplishing some of the most amazing feats of navigation and endurance in the animal world. It’s fun to laugh at these ideas of old, but they’re also a reminder that what is rational today may be ridiculous tomorrow. As Richard Feynman once reminded us to ask ourselves, “what witches do we believe in now?”

If you want to learn some amazing (true) science about where birds go during winter, how they navigate, and how they power their epic excursions, check out my latest video: “Where Do Birds Go In Winter?”, or watch it below:

Humans may have migrated out of Africa in phases based on the weather

Considerable debate surrounds the migration of human populations out of Africa. Two predominant hypotheses concerning the timing contrast in their emphasis on the role of the Arabian interior and its changing climate. In one scenario, human populations expanded rapidly from Africa to southern Asia via the coastlines of Arabia approx. 50,000 to 60,000 years ago. Another model suggests that dispersal into the Arabian interior began much earlier (approx. 75,000 to 130,000 years ago) during multiple phases, when increased rainfall provided sufficient freshwater to support expanding populations.

Ash Parton and colleagues fall into the second camp, “The dispersal of early human populations out of Africa is dynamically linked with the changing climate and environmental conditions of Arabia. Although now arid, at times the vast Arabian deserts were transformed into landscapes littered with freshwater lakes and active river systems. Read more.

Polar bears migrate north as rising temperatures hasten Arctic ice melt

It was just a theory, but for years scientists believed what years of observation were telling them. As Arctic sea ice melted because of climate change, polar bears appeared to be creeping their way toward a final refuge in the icy Canadian archipelago.

Now a study of polar bear DNA backs that up. Scientists who research the animals across the Arctic teamed up to produce a paper showing that the “directional gene flow” of recent polar bear generations is “moving towards areas with more persistent year-round sea ice”.

A pair of curious young polar bears play together in Bernard Spit, Alaska. Photograph: Stephen Kazlowski /Barcroft Media

Study of ancient dogs in the Americas yields insights into human, dog migration

CHAMPAIGN, Ill. — A new study suggests that dogs may have first successfully migrated to the Americas only about 10,000 years ago, thousands of years after the first human migrants crossed a land bridge from Siberia to North America.

The study looked at the genetic characteristics of 84 individual dogs from more than a dozen sites in North and South America, and is the largest analysis so far of ancient dogs in the Americas. The findings appear in the Journal of Human Evolution.

Unlike their wild wolf predecessors, ancient dogs learned to tolerate human company and generally benefited from the association: They gained access to new food sources, enjoyed the safety of human encampments and, eventually, traveled the world with their two-legged masters. Dogs also were pressed into service as beasts of burden, and sometimes were served as food, particularly on special occasions. Read more.