Curiously, the collective noun for crows is "a murder." Curious, since research has shown that when a crow dies, other crows gather to investigate what has happened in order to identify potential threats to the group.
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On an early summer's evening in Berlin, a growing crowd of crows (a "murder", if you will) are gathering, somewhat ominously, around two large trees in a small park.
There are possibly 100 or more of them, but they don't seem happy. They are cawing and squawking loudly as they fly around, circling each other, a growing urgency in their cries. After the lengthy conference, they fly off together into the distance, the mystery of the crow cacophony no clearer.
What could explain such behavior? Despite the "bird-brained" misnomer, crows — and other members of the Corvidae family, such as ravens, rooks, jays and magpies — are intelligent creatures. Various studies have shown their ability to develop and shape their own tools for gathering food, recognize individual human faces and even learn modes of human speech.
Counting crows
Research published in the scientific journal Animal Behavior has uncovered another telling insight into crow intellect, one which may explain the striking scene outlined above.
Shooting crows in Switzerland
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The University of Washington study suggests that when crows see that a fellow crow has died, they gather together in large numbers in a sort of 'crow funeral'. However, the aim is not to mourn their fallen friend; rather it is to investigate the reasons for the death so as to identify possible threats to the group.
In the experiment, snacks were put on the ground to attract crows and once a group had gathered, a stuffed dead crow was placed near the feeding spot.
When the researchers stood near the dead crow, crows would gather and loudly caw to each other — a process known as "scolding". In some instances, they attacked researchers and continued to react in this way even when the researchers returned multiple times without a stuffed bird.
The crows did not react in the same way to other taxidermied bird species left on the ground and likewise, other bird test groups, such as pigeons, paid little or no attention to the presence of a taxidermied version of their own kind.
A mythical association
The results supported previous research that suggests crows actively learn about the places associated with the death of one of their species, and can also learn and remember the people apparently complicit in the events.
AnotherUniversity of Washington study into crow behavior found that, several years after a researcher wearing a mask had trapped a small group of crows on campus, crows continued to "scold" anyone wearing that same mask walking through campus in ways that were markedly distinct from how they interacted with other people — displaying the ability to identify a human face and associate it with a specific threat, several years after that initial threat had been identified.
Crows live everywhere in the world except Antarctica and are deeply embedded in the folklore of many global cultures. More often than not, they are associated with death and seen in myth as being unusually in tune with such baleful matters.
The most recent scientific research suggests such associations are far from random. The next time you see a "murder" of crows gathering, it is entirely possible that they are investigating the demise of a comrade.
Migratory birds: The real long-distance champions
For any human flier, 14,000 kilometers in one stretch would be a challenge. But as birds cross oceans and continents, many species — including endangered ones — pull off this feat without the aid of jet engines.
Image: AP Photo/David Guttenfelder on assignment for National Geographic Magazine
The long-distance champion
Meet the bar-tailed godwit: Breeding primarily on Arctic coasts, and the Scandinavian and Siberian tundra, this wading species spends the winter in Australia and New Zealand. In 2007, a tagged bird was recorded as having flown 11,600 kilometers (7200 miles), from Western Alaska to New Zealand, in a single nine-day stretch. That probably makes it the record-holder for non-stop flight.
Image: picture-alliance/dpa/McPHOTO
The little guy
Named for the bright red plumage under its beak, the ruby-throated hummingbird can grow up to 9 centimeters (3.5 inches) and weigh as little as 3 grams. But don't let the bird's small stature fool you, it still gets around. During migration, some specimens fly 900 miles non-stop across the Gulf of Mexico to their breeding grounds in the Eastern United States.
Image: Imago/D. Delimont
The officer
Belonging to the stork species, the greater adjutant owes its name to its gait — which is said to resemble that of a military officer. But the adjutant doesn't command much land anymore. It's listed as endangered, and is only found in two breeding colonies in India and Cambodia. Outside of the breeding season, it visits neighboring countries across Southeast Asia.
Image: picture-alliance/dpa
'The Bird'
An invasion of sooty shearwater birds in California in 1961 was the inspiration for Hitchcock's famous thriller "The Birds," which came out two years later. In real life, the birds are more awe-inspiring than scary. Crossing the Pacific and Atlantic, up coasts in spring and down in autumn, they clock up to 14,000-kilometer journeys. Oh, and they can also dive down to more than 60 meters.
Image: picture-alliance/dpa/K. Wothe
The sewing machine
Dunlins are small waders, and breed in Arctic regions. While those from Northern Europe and Asia fly as far as Africa for the winter break, their Alaskan and Canadian counterparts prefer the much closer North American coasts. Their characteristic mechanical way of picking at food has earned them their nickname.
Image: picture-alliance/dpa/M. Woike
The snowbird
Arctic terns have developed the ultimate strategy to evade winter: They breed in the Arctic during the northern summer, then travel to the shores of Antarctica, racking up 80,000 kilometers of travel or more per year in the process. That means they see two summers. But winters? Zero. Every year.
Image: picture-alliance/dpa/H. Bäsemann
The holy bird
Critically endangered, the northern bald ibis is now only found in southern Morocco. It used to migrate across Europe, North Africa and the Middle East. Revered by the ancient Egyptians and said to have been the first bird to be released from Noah's Ark, Turkish pilgrims also looked to them for guidance on their way to Mecca. Spiritual appreciation hasn't helped stem its decline.
Image: picture-alliance/dpa/M.Unsöld
The all-rounder
The northern wheatear has nothing to do with wheat or ears but it does make one of the longest migrations of any small bird. It passes over oceans, snow and desert during its spring journey from Sub-Saharan Africa to the Northern Hemisphere. There, the birds occupy an area stretching from Central Asia to Europe and Alaska. Trackers have shown they can travel 290 kilometers a day on average.
Image: picture-alliance/blickwinkel/M. Woike
The commoner
The common crane is a common appearance in the north of Europe and Asia, where it breeds typically in moors and wetlands. For its winter vacation, it commonly migrates to North and East Africa, as well as to Israel and parts of Iran.
Image: picture-alliance/dpa/J. Büttner
The harlequin
Anything but boring, the ruddy turnstone's plumage features a harlequin-like pattern during summer when it breeds in the Arctic Tundra of Europe, Asia and North America. As temperatures drop, the small wader changes into its brown winter coat and migrates south on coastlines around the world.
Image: picture alliance/blickwinkel/M. Woike
End of a journey
These ducks had made it across the Mediterranean from North Africa only to be shot on arrival at this beach in Albania. Every year, hunters kill many millions of migratory birds across the Mediterranean — for food or money, or, most controversially, sport.
Image: AP Photo/David Guttenfelder on assignment for National Geographic Magazine