[ By Steve in 7 Wonders Series, Animals & Habitats, Nature & Ecosystems. ]
/> Animal migrations are some of the most moving (literally) phenomena Mother Nature has to offer, and these 10 amazing examples redefine the word “superlative” on a number of levels. Fastest, largest, longest and even stupidest – when animals migrate, they often do it in a BIG way.
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Monarch Butterflies: It’s a Wing Thing
(images via: NHM, Kitlist, MonarchButterfly.com and CitizenShift)
The mass migration of Monarch Butterflies is arguably the longest – both in distance and time – of any insect species. Conducted over a number of seasons and generations, perhaps the most amazing thing about the Monarch migration is that their overwintering refuge in central Mexico’s Oyamel Fir forests wasn’t discovered until 1975!
(images via: ButterflyWebsite and VeryVeryFun)
Will the majestic Monarchs be able to continue their epic migrations in the coming years? They face a range of difficulties, some but not all the result of human activity. Illegal logging, land clearing and simple population pressure will likely increase but besides these, regular El Nino events such as the one in 2009-2010 soak their winter refuges with rain, sleet and snow. Can the Monarchs persevere? Only time will tell.
The Great Wildebeest Migration
(images via: Dualdocs, Luxury Safari Holidays and Art.com)
The annual migration of over 1 million African Wildebeest and Zebras has been well documented by filmmakers and wildlife documentary producers for decades. Every February in the Ngorongoro area of Tanzania’s southern Serengeti plains, the “Great Wildebeest Migration” begins.
(images via: Tamimiea)
The exact starting date depends on the progress of the calving season during which around 500,000 calves are born, but by early March up to a half million zebra, nearly 2 million wildebeest and around 100,000 other grazing animals are on the move, headed towards the fertile plains and woodlands of the western Serengeti across the border in Kenya’s Masai Mara region.
(images via: Southern-Africa, Allposters and Mirror UK)
The final obstacle for the Serengeti’s thundering herd is also the most challenging: the Mara river. Animals already weakened by weeks of travel through dry and barren savannah offering little food or water must now run the gamut of flood-swollen, rushing waters and swarms of hungry crocodiles. Around 250,000 wildebeest will die during the course of their 1,800-mile migration but the herds have proved to be remarkably resilient.
Worst Case of Crabs EVAR
(images via: Telegraph UK, Environmental Graffiti and The Fortuno)
Christmas Island, an isolated Australian territory located in the Indian Ocean, is home to about 1,400 people.. and up to 120 million Red Crabs. Luckily for the inhabitants the crabs aren’t carnivorous (just occasionally cannibalistic), but their sheer volume results in a unique spectacle played out each year when tens of millions of the burrowing crabs migrate to the sea to lay their eggs.
(images via: Annu Journal, Parks Australia and Jurgen Freund)
That’s only half the story – once the baby crabs complete their marine larval phase, they clamber back onto the shore and migrate into the island’s central rainforest. Although the baby crabs are very small, they make up for their size with numbers: each adult female releases about 120,000 fertilized eggs. You can do the math, my calculator can’t display that many zeros! The “red tide” of young crabs that sweeps across beaches, through towns and across gold course has to be seen to be believed… so here it is!
Christmas Island Giant Red Crab Migration, via Wicksy03
Arctic Terns: Long Distance Voyagers
(images via: Alaska.org, Burke Museum and TheWE.cc)
It’s not only human jet-setters who see two summers every year; the Arctic Tern has been doing it for countless centuries. This smallish seabird holds the record for the longest migration route of any known creature.
(image via: MichaelPoliza)
The Arctic Tern’s travels take it from breeding grounds in northern Canada down to the southern ocean off the Antarctic continent, and back again. Considering the terns’ indirect course used to take advantage of prevailing winds, the average bird will make a 45,000 mile (over 70,000 km) round trip each year.
(images via: PlanetEarth, EDroper and Drunk On Blue)
Arctic Terns are long-lived birds that can live upwards of 30 years. It’s estimated that in the course of a lifetime, these long distance champions will fly over 1.5 million miles (2.4 million km)… enough to take it to the Moon and back 5 or 6 times!
Caribou: Have You Herd?
(images via: ArcticWild, Delta News Web and LA Times)
One of the longest known and best documented large-scale animal migrations is that of the northern Caribou. Not all caribou migrate and those that do, don’t always follow the same route each time. Much depends on the vagaries of the weather – and based on that, the availability of food.
(image via: Alaska In Pictures)
The three largest herds of caribou are the George River herd in northern Quebec province in Canada, the the Western Arctic herd based in northwest Alaska, and the Taimyr Peninsula herd found across the Bering Strait in Siberia. Large caribou herds migrate from about 100 to over 500 miles each year.
(image via: Sydney Morning Herald)
A few fun facts about Caribou… did you know that herds once roamed the Great Lakes states and Maine? Though Caribou and Reindeer are of the same species, the latter term is used to refer to domesticated caribou kept most commonly by the Sami people of northern Scandinavia’s Lapland region.
March of the Emperor Penguins
(images via: Independent UK and Te Ara)
Emperor Penguins aren’t the only species of this iconic antarctic bird that migrate but they are perhaps the most famous, thanks in part to the beautifully filmed chronicle entitled March of the Penguins. These magnificent creatures are highly adapted to the incredibly harsh conditions they live in; even so, breeding during the bone-chilling, pitch black Antarctic winter is a monumental achievement in and of itself.
(image via: National Science Foundation)
Though the migration of Emperor Penguins to and from their inland nesting grounds may seem short compared to that of other animals in more temperate climes, the journey is fraught with hardships and the margin for error is exceedingly thin.
(images via: Care2, Easycinema and Snow Girl)
So well adapted are Emperor Penguins to the Antarctic’s hostile conditions, the species is not considered to be threatened. Currently around 30 colonies exist and their population fluctuates due to weather conditions and the varying distance from their nesting grounds (which remain in the same place) and the constantly shifting edge of the sea ice.
The Return of the Swallows to San Juan Capistrano
(images via: Home Exchange, Jonron Real Estate and MV Chris)
A miraculous migration, is what some call the annual return of the Swallows to Capistrano. It’s an event that has taken on the luster of romance and sentimentality as each year on March 19th – St. Joseph’s Day – the swallows traditionally make their return to the Mission San Juan Capistano in the town of San Juan Capistrano, California, near San Diego.
(image via: Boston.com)
The Mission was founded by Franciscan friars on on All Saints Day (November 1st) of 1776 and its arched belfry soon attracted the local swallows who used its shelter to protect their nests. An earthquake in 1812 exposed the rafters of The Great Stone Church but the Cliff Swallows were not dissuaded from nesting there. Where do the swallows return from, you might ask? Their migration is actually somewhat miraculous as they fly 6,000 miles (10,000 km) south to their wintering range in Goya, Argentina, and then must make the long and arduous return trip.
Gray Whales: It’s No Fluke
(images via: Learner.org, UCI/Richard Ellis and Hickerphoto)
Gray Whales are a popular sightseeing attraction in and around Baja California but few are aware of the creatures’ long distance migration. In fact, Gray Whales have the longest migration route of any mammal, land or sea.
(image via: BBC/Photolibrary)
Each year, these medium-sized, mild-mannered cetaceans make a round trip of 10,000-12,000 miles (around 18,000 km) between their winter calving lagoons off southern California and Mexico and their preferred summer feeding grounds around Alaska’s Aleutian Islands and the Bering Strait
(images via: QSI.net and Anchorage Daily News)
Besides providing enjoyment for whale-watchers up and down the California coast, Gray Whales have another claim to fame: the 1988 effort to rescue three whales who overstayed in the arctic and became trapped in sea ice off Point Barrow. The drama was closely followed on American television and the rescue (which cost $5.5 million) entailed the use of Coast Guard helicopters dropping 5-ton concrete pillars to break up the ice and a Soviet icebreaker that helped carve a path from the whales’ shrinking pool of unfrozen water to the open sea. Cold War indeed!
Legend of the Lemmings
(images via: Balsamia and CSMonitor)
Lemmings are a species of rodent found in northern Scandinavia, Siberia and Canada’s arctic regions. Being a herbivore in the tundra is a risky proposition and lemming populations rise and fall – sometimes precipitously – in good times and bad. Normally solitary creatures, lemmings may go on mass migrations when biological urges dictate the need to find new feeding grounds. At times, rivers and cliffs may block their paths – be assured, though, that lemmings who fall or drown in the process of migration do not do so willingly.
(images via: Voyages Extraordinaires, Tradition In Action and Free Readings Online)
A widely believed myth about lemmings is that they occasionally erupt across the arctic landscape on suicidal “death marches”, sacrificing themselves for the betterment of the species when food supplies run short. Not so – the myth was perpetuated by a 1958 Disney nature documentary called “White Wilderness”. It was later revealed that the film was made with the extensive use of staged footage, such as lemmings being filmed on a snow-covered turntable or launched into the air by (human) hand. Here’s a short video compilation from the film that features ONLY the fake footage:
White Wilderness (edit), via Complience
Passenger Pigeons, RIP
(images via: Ulala.org and Artists and Art/Kevin Sloan)
One of the greatest migratory species in history is… history. Passenger Pigeons by the hundreds of millions used to darken American skies for hours, even days at a time as they migrated to and from their forested nesting grounds. It was said that the ground beneath their roosts was covered with up to 2 inches of droppings and the branches of mature trees would snap under the weight of dozens of nests. At its greatest, the total number of Passenger Pigeons was estimated to be about 6 billion birds. So, what happened?
(images via: Mapmakers Opera, Wilson’s Almanac and Silverfish Attack)
WE happened… the perfect predator meeting the perfect prey. Passenger Pigeons were low fliers whose nests were easily accessible. They were also, from all accounts, quite tasty. By 1880 the massive migrating flocks were no more and the last wild bird was shot in 1900. The last of the species, a captive bird named “Martha”, died in 1914.
(image via: UCG Mike Bennett)
We know today that human hunters were not the sole cause of the Passenger Pigeon’s demise. Habitat loss was a major factor – as the sprawling forests of the eastern U.S. were cut down, the pigeons had nowhere to roost. In addition, the birds could not adapt to the emerging paradigm of The Earth Plus Humans, unlike their Rock Dove and Mourning Dove cousins. It was a “perfect storm”… from which the Passenger Pigeon was unable to emerge.
/> The sad tale of the Passenger Pigeon echoes into the modern age as a warning of what might be. Safety in numbers is a relative term – when the numbers add up wrong, your numbers will decrease. There was no such thing as “environmental awareness” a century ago and it’s assumed humanity has learned a lot about peaceful coexistence with the rest of the animal kingdom. The fate of the world’s remaining migratory species will prove if we really have learned, or are doomed to repeat the same mistakes.
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There are few sights and sounds more able to instill us with delicious, jellifying terror than a full-blooded lighting storm. There are 16 million across the globe every year. But how do they form and how do they work? To find out, we look at 10 different types of electrical discharge from the small-scale to the gut-wrenchingly huge – and maybe gain a new appreciation, tinged with fearful awe, of what happens when Mother Nature turns the lights on.
Cloud To Ground Lightning
How do you make lightning? Easy. All you need is a couple of hundred cubic miles of air, a large space above it (40,000 vertical feet is a nice number), and a massively powered heat-engine – say, the Earth. Ready? Take your air and steadily heat it up. As it rises, it will cool and condense into droplets of water vapour in fluffy, opaque clumps. Congratulations – you are now the proud owner of a bouncing baby cumulonimbus.
Now for the science bit. For reasons that are by no means clear, some parts of the cloud shed electrons and other parts gain them – in other words your storm-cloud gains an electrical charge, the top becoming positive and the base negative. Where you have opposite charges, you have an electrical field between them. Excitement all round. But all this fun isn’t limited to the sky – thanks to the rules of electrostatic induction, the ground gains an equal and opposite charge to the nearest part of the cloud lying overhead. Now you have perfect conditions for a bridging spark of truly epic proportions.
(Image via: jfyffe)
Once the field is strong enough, the air ionizes into plasma, a far better conductor of electricity. This happens unevenly, forming “paths” of plasma through the storm that provide crooked lines of least resistance for lightning – these are known as step leaders. In a fraction of the blink of an eye, step leaders fan down through the cloud and out the bottom, branching downwards like the roots of a tree. As this truly wondrous high-speed footage shows, all it takes is for one of these faintly glowing channels to connect with the ground…and ZAP. You just made lightning. Safety announcement: since it is hotter than the surface of the Sun (a toasty 30,000 °C), be sure to take a few steps back – not that you have time, as a lightning bolt travels at 130,000 miles an hour.
Ground to Cloud Lightning
Sometimes the ground will give lightning a helping hand – an upward-pointing thread of positively-charged plasma called a streamer. All objects on the ground will create their own streamers (including human bodies) which attempt to meet the downward-traveling step leaders halfway. When these streamers are of an unusual size, they become the dominating leaders and the resulting bolt of lightning will travel upwards. The taller the object, the more likely it is that one of its streamers will attract or emit a lightning bolt – which is why it is good practice to avoid trees in a storm.
Cloud to Cloud Lightning
But why go as far as the ground? Clouds can earth themselves (for want of a better word) by firing bolts between their oppositely-charged regions, either as intracloud lightning or the much rarer intercloud variety (from one cloud to another).
If you’re watching a thunderstorm, most of the light show is intracloud lightning. Aircraft pilots are particularly wary of intercloud bolts for one very good reason – they shoot across their flightpaths.
Anvil Lightning
It seems ludicrous to describe something moving at 36 miles a second as “crawling”, but that is what anvil lightning does – spreading horizontally across the sky, giving the eye just enough time to discern its movement.
(Image via: Yeeta)
A particularly dangerous variety of anvil lightning is the “bolt from the blue” – a strike that moves horizontally away and out from the cloud before curling back down to earth, sometimes appearing out of a blue sky. As it originates in the positively-charged upper regions of a cloud, this is a form of positive lightning – massively charged and extremely hazardous.
Ribbon Lightning
Ribbon lightning is lighting that gets blown sideways by the wind. No, really. Remember, lightning follows the paths of ionized air particles – and if the wind is strong enough, these particles will scud sideways, parallel to the observer. Any further lightning bolts will also appear to have been blown by the wind.
What we regard as a discrete flash of lightning is usually a flurry of bolts in both directions – and ribbon lightning (looking for all the world like bad camerawork) is the result of the afterimage of displaced return strokes of lightning registering on the human eye or digital CCD.
Bead Lightning
Weirder still (and rarely captured on film) is bead lightning, the result of the lightning trail cooling down and breaking up into a string of bright, often spherical sections, visible for anything up to a second. It is not known if this is a product of standard irregularities in the path of the lightning, or if some atmospheric factor is malforming the lightning itself.
Sprites, Jets and Elves
If anything illustrates how little we understand electrical storms, it is what happens above the clouds. They have been anecdotally recorded for decades, but it was only in 1994 that cameras first captured proof of the existence of a bizarre, colorful family of electrical discharge. We have termed them jets, sprites and elves – and they have modern science somewhat flummoxed.
Red sprites (and yes, that is their actual color) appear to be intense directed explosions of high-energy electrons triggered by positive lightning or cosmic radiation. They burst upwards at relativistic speed, almost too quick for the naked eye, to a height of almost 100 km. And…that is about all we know, so far. If you can bear the accompanying music, watch them in action here.
Ball Lightning
Some people argue there’s no such thing. Other people post their YouTube videos and stand by them to the bitter end. But whether it truly exists or not, ball lightning has polarized (sorry) popular imagination ever since the above photo by a Japanese student started circulating. Until it is definitively captured on film or reproduced in the lab, it remains a case for Mulder and Scully.
St. Elmo’s Fire
Thanks to the late great John Hughes, everyone has heard the name – but what exactly is it? For the answer, we go back to the effect of electrical charge upon the air in a thundercloud. When grounded objects start to accumulate charge, they ionize the surrounding air and turn it to plasma, accompanied by an eerie blue glow and a flicker of small-scale electrical discharges. Remember that plasma makes it much easier for lightning to strike? Then you’ll know why St Elmo’s Fire is a very bad thing to encounter on your travels – and why this video of a commercial flight passing near a thunderstorm is not for the faint-hearted.
Volcanic Lightning
Lastly we come to a manifestation of lightning where everything comes together and anything goes. When volcanoes erupt, they unleash lightning storms of staggering ferocity. Talking of the eruption of Vesuvius in 79 AD (and the destruction of Pompeii), Pliny the Younger wrote: “behind us were frightening dark clouds, rent by lightning twisted and hurled, opening to reveal huge figures of flame.”
The mechanics of volcanic lightning aren’t yet known – it seems likely that water vapour released from magma forms a localized, super-concentrated form of storm cloud, unleashing a terrifyingly accelerated bout of electrical activity. Whatever the underlying causes, it’s clear that while the best advice for avoiding standard lightning is to get somewhere safe and crouch in a ball, if it’s volcanic lightning- you get out of there fast. Some storms aren’t meant to be weathered by mere mortals.
Mike
