Sunday, October 9, 2011

Elephant Bird (Aepyornis)


Elephant birds were among the heaviest birds that have ever existed. Following the extinction of the last dinosaurs 65 million years ago, the mighty reptiles that had dominated the earth for more than 160 million years, the long overshadowed birds and mammals evolved into a great variety of new species, some of which gave rise to giants like the elephant bird.

In their general appearance, elephant birds were similar to the fiightless birds called “ratites” with which we are familiar today, such as the emu ( Dromaius novaehollandiae ), ostrich ( Struthio camelus ), rhea ( Rhea  sp.), cassowary ( Casuarius  sp.), and kiwi ( Apteryx  sp.); however, the biggest elephant bird,  Aepyornis maxiumus,  was enormous. It was about 3 m tall and probably weighed about 450 kg (the giant moa of New Zealand was actually taller but was way behind the elephant bird in terms of bulkmoa are discussed later in this chapter). On the island of Madagascar, there were few large predators, and the ancestors of the elephant birds had no need to fiy; therefore this ability was gradually lost. Grounded, these birds went on to become animals that were bound to the land. Their skeletons show that they had very powerful legs and that they plodded around Madagascar on their big feet. The wings were reduced to tiny structures and were probably not visible beneath the bird’s plumage. These birds had become so well adapted to a life without fiight that the large and specially modified chest bone (keellike sternum) found in most birds, which serves as an attachment for the wing muscles, had all but disappeared.

We don’t know exactly what the elephant birds ate, but we can assume from the shape of their bill that they were not carnivorous. Some people have suggested that certain Madagascan plants that are very rare today depended on the elephant birds for the dispersal of their seeds. The digestive system of these large birds was ideally suited to breaking down the tough outer skins of these seeds. Some were digested, but others passed through the bird intact and in a state of readiness for germination.

The remains of the elephant bird that have been found to date allow us to build up a picture of how this extinct animal lived. The most intriguing remains are the bird’s eggs. Some have been found intact, and they are gigantic—the largest single cells that have ever existed. They are about three times bigger than the largest dinosaur eggs, with a circumference of about 1 m and a length of more than 30 cm. One of these eggs contained about the same amount of yolk and white as 200 chicken’s eggs. These huge shelled reminders of the elephant bird are occasionally unearthed in the fields of Madagascan farmers, and one is even known to contain a fossilized embryo.

The number of elephant bird species that once inhabited Madagascar is a bone of contention among experts, but it is possible that Madagascar supported several species of these large birds. On their island, surrounded by abundant food and few animals to fear, especially when fully grown, the elephant birds were a successful group of animals. Then, around 2000 years ago, their easy existence was overturned as humans from Africa, Indonesia, and the islands around Australia reached this isolated land of unique natural treasures. Humans by themselves are one thing, but thousands of years ago, humans did not travel alone—they took their domestic animals with them. The elephant birds, in their 60 million years of evolution, never saw a human, and they wouldn’t have recognized them as dangerous. The humans, on the other hand, saw the elephant birds as a bounteous supply of food. Hunting had a disastrous eff  ect on the populations of these giant birds. They had evolved in the absence of predation and, as a result, probably reproduced very slowly. To add insult to injury, the animals the humans brought with them—pigs, dogs, rats, and so on—made short work of the elephant bird’s eggs. Other introduced animals, such as chickens, may have harbored diseases to which these giant birds had never been exposed. With no natural immunity to these pathogens, epidemics may have ravaged the populations of elephant birds, which were already under pressure from hunting and egg predation. Changes in climate may have led to the drying out of Madagascar, and this, too, could have aff  ected the populations of these impressive birds. The actual extinction timeline for the elephant birds is sketchy, but many experts suppose that the last of these great birds died out before 1600. The means at our disposal for the aging of ancient material are constantly improving, and some recent estimates move the disappearance of these birds into the nineteenth century. It is possible that some stragglers managed to survive until recent times, but we can be certain that no elephant birds survive today. 

Source: Wikipedia

Warrah (Dusicyon australis)


Remote and treeless, the Falkland Islands is a small archipelago in the South Atlantic Ocean. Ravaged by incessant winds and terrible winter storms, these islands are a very harsh environment. Although the Falklands are a welcome refuge for marine animals such as penguins, seals, and sea lions, very few land animals have managed to make a living on this stark, oceanic outpost. The only mammals known from the Falkland Islands are a small species of mouse and a mysterious dog, the warrah, which also goes by the names of “Falkland Island fox” and “Antarctic wolf. ”

Whether the animal was a fox or a wolf is a bone of contention among mammal experts. Contemporary accounts of the living animal as well as stuff  ed skins show that this carnivore had both wolf and fox characteristics. An adult warrah was about twice as big as a red fox (1.6 m long), with a large, wolfish head, but because of its short legs, it was only about 60 cm tall at the shoulder. Its tail, unlike that of a wolf, was thickly furred, and like a fox, it excavated dens in the sandy soil of the coastal dunes. Apart from mice, the land of the Falkland Islands supports precious little prey that sustained the warrah, but it is possible that insect larvae and pupae featured prominently in its diet. Although the interior of the Falkland Islands is rather impoverished when it comes to carnivore food, the coast is a bounteous source of nourishment at certain times of the year. The islands are used by numerous marine animals, including seals, sea lions, penguins, and a variety of fl  ying seabirds. When these animals were raising their young, times must have been good for the warrah, and it probably made off   with eggs, nestlings, adult birds, and even young pinnipeds. To reach these good supplies of food, the warrah traveled along well-worn paths that must have been made by generations of the animals accessing their feeding grounds via the shortest possible route. Although the southern spring and summer was a time of abundance for the warrah, the autumn and winter were probably very tough, and some accounts from the eighteenth and nineteenth centuries report that the living animals looked starved and very thin. 

Regardless of its wintertime depravations, the warrah, in the absence of competition, appears to have been a successful species that was quite numerous on the two main islands of the Falklands group. This monopoly came to an end with the arrival of humans. Initially, visitors to the Falkland Islands were afraid of the warrah as it would wade into the water to meet an approaching boat. This was not an act of aggression, but an act of curiosity. The warrah had probably never seen humans and had therefore never learned to be afraid of them, an unfortunate fact that contributed to the extinction of this interesting dog. 

Although the Falkland Islands are a harsh place, certain breeds of hardy sheep were well suited to the conditions, and they were introduced to the islands as a way of laying the foundations for the first human colonies on the islands. The sheep thrived on the islands, and as humanity tightened its grip on the Falklands, the warrah was seen as a menace that had to be exterminated. Like all dogs, the warrah was an opportunistic feeder, and it undoubtedly fed on the introduced sheep and lambs that nibbled the Falkland Island grass, but islanders, in their ignorance, believed the warrah was a vampire that killed sheep and lambs to suck their blood, only resorting to meat eating in times of desperation. Horrific myths can be very compelling, especially on a group of small islands where news travels fast and where livelihoods are at stake. In an attempt to quell the populace, the colonial government of the Falkland Islands ordered a bounty on the warrah, and fur hunters soon moved in to collect handsome rewards for delivering the pelts of dead animals. 

The Falkland Islands, with a land area roughly the size of Connecticut, could never have supported huge numbers of warrah. Even before the human invasion, the warrah population was probably no more than a few thousand individuals, and it is therefore no surprise to learn that hunting quickly led to the extermination of this animal. Because the warrah was so very tame, hunting was a breeze, and all the hunter needed was a piece of meat and a knife. He held out the piece of meat to tempt the animal and stabbed it with the knife when it came within range. Other hunters used rifl  es or poison, but regardless of which particular method was used to kill the warrah, it was exceedingly rare by the 1860s. 

Amazingly, a live warrah found itself in London Zoo in 1868 after being transported on a ship with a menagerie of other exotic animals, most of which perished during the journey. This warrah, far from home, survived for several years in the zoo, but it was one of the last of its species. Back in the South Atlantic, the onslaught of the sheep farmers and the hunters was too much for the poor warrah, and in 1876, the last known animal was killed at Shallow Bay in the Hill Cove Canyon. 

Source: Wikipedia

Tarpan (Equus ferus)

It may come as a surprise, but the domestication of the horse stands out as one of the most signifi  cant moments in human history. This seemingly insignifi  cant event changed the way we lived forever. It enabled our ancestors to travel quickly over huge distances, and they harnessed the strength and tenacity of these animals to do tasks that previously required several men. Also, when the useful life of the horse was over, its flesh provided sustenance and its skin, bones, and sinews were turned to a multitude of uses. 

What are the origins of these fi  rst domestic horses? What were they, where did they come from, and how did they live? It is widely accepted that the ancestor of the majority of modern horses was an animal known as the tarpan. This sturdy horse was only around 1.5 m at the shoulder and therefore very small compared to a modern Thoroughbred racehorse. However, what the tarpan lacked in size it more than made up for in resilience and stamina. Being an animal of the Asian steppes, it was able to survive in the very harsh conditions that sometimes sweep over these treeless plains. In the wintertime, its grayish brown coat grew long to give it added protection from the cold. In some of the more northern reaches of its range, the tarpan may even have been white. According to some of the Evenk people, ivory hunters searching for the tusks of mammoths in the deep permafrost of Siberia would often fi  nd white horses. It is possible that these could have been white tarpan that met their end in a bog, only to become entombed in ice as the earth entered another of its many glaciations. 

Like other horses, the tarpan was a grazer and a herd animal. Like many other fleet footed animals, the tarpan found protection from its predators by living in a herd. Long ago, the Asian steppe was prowled by many diff  erent predators, many of which were perfectly able to catch and subdue an animal as large as the tarpan. One by one, the tarpan’s predators died out, leaving only the wolf, the occasional bear, and of course, humans. By all accounts, the tarpan was a very spirited animal and quite capable of defending itself by kicking and biting. Humans are known to have killed the tarpan by driving herds of them off   cliffs, a surefi  re way of killing lots of them quickly. 

Horses are shown in many cave paintings throughout Europe, and it is very likely that the tarpan and its relatives were simply hunted before an ancient innovator thought it would be a good idea to try to tame them. Hunting these animals on the steppes must have been very hard as horses have excellent smell and hearing and can sense the approach of danger way before they can see it. When the domestication breakthrough came, hunting was made much easier on the back of a tame tarpan, and the species began its slow, inexorable slide toward extinction. Hunting was not the main problem facing this species. As people became aware of the usefulness of the tarpan, more and more would have been taken from the wild to supplement the young that were reared from the tame individuals. The numbers of the domesticated tarpan grew, and over time, their distinctive characteristics, such as aggression and spiritedness, were fi  ltered out in the process of selective breeding to produce a horse that was calm and cooperative. These animals were less like tarpan and more like today’s horses. Unfortunately for the tarpan, it could still mate with these domesticated horses, and its unique genes were diluted. This continued until the middle of the nineteenth century, when it was realized that purebred tarpans were very rare. In 1879, the last wild tarpan was killed, but some had been taken into captivity years before and were often kept on the private estates of noblemen. These captive animals dwindled due to neglect, and the last one died in Poland in around 1887. When the tarpan became extinct, domesticated horses had found their way all over the world, as human explorers took them wherever they went. 

In a vain attempt to resurrect the tarpan, the Polish government collected together a number of ponies that were considered to have tarpan characteristics. These were taken from their peasant owners and sent to forest reserves. This was a pointless exercise as the ponies they chose were a product of millennia of selective breeding and they were no more purebred tarpan than a German Shepherd dog is a purebred wolf. The same German scientists who thought it would be possible to resurrect the aurochs turned their attention to recreating the tarpan by selective breeding. This notion sorely lacked merit because no one knew or knows to this day what constitutes the tarpan on a genetic level. These attempts at selective resurrection did produce two types of horse, the Konik of Poland and the Heck of Germany, which are thought to resemble the tarpan superfi  cially. 

The story of the tarpan is an interesting one because it’s not a simple case of a species being extinguished. Through our desire to produce an animal that was of use to us, we took the tarpan and molded it to our own needs, in the process producing something quite distinct. The tarpan our ancestors knew is no longer with us in a form they would recognize, but its genes are there in the cell of almost every horse.

Source: Wikipedia

Saturday, October 8, 2011

Stephens Island Wren (Xenicus lyalli)

Rising to heights of around 300 m, Stephens Island looms off   the northernmost tip of Marlborough Sound on South Island of New Zealand. The island is tiny (2.6 km2), but it is a refuge for many animals that have disappeared from the mainland since the arrival of Polynesians.

On this prominent lump of rock, there once lived a small bird known as the Stephens Island wren. This bird was unrelated to the familiar wrens of the Northern Hemisphere and actually belonged to a small group of perching birds endemic to New Zealand. The remains of this small bird have been found at various sites throughout the main islands of New Zealand, and it seems that Stephens Island was the last refuge for this bird following the arrival of humans and the animals they brought with them. One animal in particular, the Polynesian rat, wreaked havoc among the populations of New Zealand’s small endemic birds. Stephens Island served as a refuge for the wren for hundreds of thousands of years, and even after the Polynesians and their animals wiped out these small birds on the mainland, the population on Stephens Island was safe—until the arrival of Europeans.

The British commandeered New Zealand as an extension of their growing empire, and in their learned opinion, what Stephens Island needed more than anything was a lighthouse to warn ships away from the rocks. In June 1879, a track to the proposed site for the lighthouse was cleared, and five years later, the lighthouse went into operation. In itself, the  lighthouse was no threat to the wren, but in those days, lighthouses were operated by people, and people have pets—often, cats.

At some point in 1894, a pregnant cat was brought to the island, and it seems that no sooner had she arrived than she gave her new owners the slip and escaped. This unassuming cat probably didn’t realize how special she was. No predatory land mammal had ever set foot on Stephens Island, and the animals on this forested outcrop were woefully ill prepared as they had never encountered any mammal, let alone one with the predatory proclivities of the domestic cat. In June 1894, one of the off  spring of the escaped cat was apparently taken in by one of the assistant lighthouse keepers, David Lyall. Lyall had an interest in natural history, and he was intrigued by the small carcasses his young pet brought back from its forays around this previously untouched island. The carcasses were those of a tiny bird, but of a sort that Lyall had never seen. With a hunch these birds were something special, he had one sent to Walter Buller, an eminent New Zealand lawyer and ornithologist, who immediately recognized the sorry-looking carcass as an undescribed species. The bird was definitely a type of New Zealand wren, related to another small New Zealand bird, the rifleman. Unlike the rifleman, the Stephens Island bird was flightless. The larger group to which these birds belong, the perching birds (passerines), has only a couple of flightless representatives.

The only information we have on the way the Stephens Island wren lived comes from the limited observations made by Lyall. According to the only person who saw this species alive, it “ran like a mouse” and “did not fly at all.” This is about the sum of the information we have on the living bird, but the structure of the bird’s skeleton and plumage allows us to investigate if Lyall was correct. The skeleton of this tiny bird bears all the hallmarks of a species that had given up the power of flight, and the plumage does not appear to be up to the job of flapping flight. We can’t rule out the possibility that this tiny bird ran and leapt or glided to catch aerial insects, but it would not have been capable of flapping its wings to any great effect. The great tragedy is that this tiny bird died out before we could learn anything more about it.

In 1894, Lyall brought a total of 16 to 18 specimens of Stephens Island wren to the attention of the scientific establishment. It is not clear if his cat caught all of these, but late in 1894, news of this bird had circulated in the ornithological community, and some collectors were willing to pay big money for a specimen—Lionel Walter Rothschild, the famous British collector, purchased nine specimens alone. With such a high price on the heads of these diminutive birds, can we be sure that Lyall didn’t go and catch some himself to supplement his income? We’ll never know, but the cats and the greed were too much for the Stephens Island wren, and before 1894 was out, the species was extinct—discovery and extinction all in the space of one year. This is pretty impressive, even by human standards of devastation. 

Source: Wikipedia

Quelili (Caracara lutosa)

Two hundred and forty miles off the northwest coast of Mexico lies the island of Guadalupe, a small volcanic island, 35 km long and about 9 km at its widest point. Even though it is barely a speck in the vastness of the Pacifi  c Ocean, Guadalupe was once home to a number of animals that were found nowhere else. One of the most famous Guadalupe residents was the quelili. This bird of prey was very closely related to the caracaras of Central and South America, and perhaps the ancestors of the quelili found themselves on the remote, rocky outpost of Guadalupe after being blown from the mainland during a storm.

The caracaras are all meat eaters, but they don’t have the hunting prowess of eagles or falcons. They are quite feeble flyers and are unable to swoop on their prey from a great height. Instead, they prefer to catch and eat small prey that can be easily overpowered, and they often resort to scavenging. The English-speaking inhabitants of Guadalupe called the quelili the “eagle,” but like the other caracaras, the quelili was no formidable aerial hunter. It apparently fed on small birds, mice, shellfi  sh, worms, insects, and carrion when the opportunity arose.

There are a few accounts of how the living quelili behaved. Its broad wings were suited to loping flight quite close to the ground, and like the other caracara species, it may have been equally at home on the ground, stalking among the low vegetation on its long legs. Small flocks of these birds were often seen in flight, but it is unclear if there was an ordered social structure. Living caracaras are normally solitary, but they will tolerate each other around a carcass, albeit with bouts of noisy quarreling. Perhaps the quelili was a little friendlier to others of its kind. They were known to communicate with complex displays, one of which involved the bird extending its neck to full length and then arching backward until its head almost touched its back (the crested caracara displays in the same way). Unfortunately, the signifi  cance of these displays is now lost, but perhaps it was the way that one quelili asserted dominance over another.

The quelili was probably the dominant predatory land animal on Guadalupe for tens of thousands of years, but due to its position in the food chain and the small size of its island home, it would never have been very common. An island like Guadalupe could have never supported more than a couple hundred quelili, but in the narrow geological window in which it lived, this bird was a successful scavenger and predator.

This success continued up until the early eighteenth century, at which time humans appeared on the scene. The first humans to make any real diff  erence to the ecology of Guadalupe were whalers and hunters, who came to catch and kill sea otters, fur seals, and elephant seals. On their ships, they carried goats as a source of meat and milk, and as a way of caching supplies on their hunting routes, they left some goats on Guadalupe. The idea was that the goats would survive and the whalers could pick up some fresh meat and milk the next time they were passing. Not only did the goats survive, but they bred in profusion, and before long, there were thousands of them running riot over the once virginal land. Goats in the wrong place can be devastating, as any gardener will attest. They eat anything and everything, and the numerous unique plants that covered Guadalupe were stripped away by thousands of hungry mouths. This in itself was not the nail in the coffin of the quelili, but the huge herds of goats soon attracted people. Some came to herd the goats and others came to hunt them, and herder and hunter alike both considered the quelili to be a meddlesome foe that would kill and eat goat kids whenever the opportunity arose. It is very unlikely that the quelili could have captured and killed a healthy goat kid, but it was probably partial to the flesh of a goat carcass. Goatherders may have seen a group of quelili tearing at the carcass of a dead goat kid and presumed the birds were responsible for its death.

By the nineteenth century, the quelili was goat enemy number one and it was hunted mercilessly. By the 1860s, rifles and poison had pushed it to the brink of extinction. As if angry goatherders were not bad enough, the quelili soon found itself pitted against an even more relentless foe: the ornithological collector. The age of discovery gripped the educated world, and the race to collect and catalogue the world’s treasures was well and truly on. Rarities are coveted by collectors, and institutions and wealthy individuals soon got wind of the disappearing Guadalupe bird fauna, including the quelili. Back in the nineteenth century, the word conservation didn’t really exist, and the collectors systematically exterminated the quelili; the skins were sold to the highest bidder.

Amazingly, one small group of quelilis survived this onslaught, but these were accounted for by Rollo Beck, an ornithologist and collector who landed on the island on December 1, 1900. No sooner had he landed on the island than he saw a flock of 11 quelili heading straight for him. In the mistaken belief that the bird was still common, he shot all but two of the flock, and in doing so, Rollo Beck consigned the quelili to extinction.

Source: Wikipedia

Pig-Footed Bandicoot (Chaeropus ecaudatus)


Australia was once home to a unique collection of beasts, including giant marsupials and fearsome reptiles. However, scurrying around the big feet of this megafauna were a huge number of small marsupials that evolved to fill most of the ecological niches occupied by placental mammals in other parts of the world. There were rabbitlike marsupials, tiny mouselike animals, even a marsupial equivalent of a mole, to name but a few. Some of these animals can still be found today, but many ended up going the same way as the other long gone denizens of Australia.

The pig-footed bandicoot was one of these animals. For millions of years, this odd little marsupial, which was no bigger than a kitten, lived throughout Australia, but in recent times, it became restricted to the arid and semiarid inland plains. This bandicoot, with its rabbit ears, was probably a familiar sight to the Australian Aborigines as it hopped and bounded around the plains.

Perhaps the oddest thing about this marsupial was the four spindly legs that supported its plump little body. It is from the animal’s feet that we get its common name. On its forefeet, there were only two functional toes with hoofl  ike nails, remarkably similar to the feet of a pig, but in miniature. The hind limbs were also highly modified as the second and third toe were fused together, and only the fourth toe, which ended in a nail like a tiny horse’s hoof, was used in locomotion. With such highly modified limbs, the pig-footed bandicoot was undoubtedly a running animal, and the gait it used depended on how fast it was moving. When it was skulking around looking for food, the pig foot moved in a series of bunny hops—taking its weight on its forelimbs and pulling its back legs along. When it chose to up the pace, the hind limbs were moved alternately and, according to Aborigines, when it really wanted to move, it stretched out and took to a smooth gallop. Not only was the pig foot quick, but it also had a lot of stamina and could run at full speed for long periods of time. 

Apart from being very fleet of foot, the pig foot was also said to be more dependent on plant food than the other types of bandicoot, which are generally insectivorous marsupials. In the wild, they subsisted on grass seeds, but in captivity, they ate a range of food, including  lettuce, bulbs, and grasshoppers. It is said that during the hottest part of the day, they would seek refuge from the sun’s rays in a grass nest, only venturing out to seek food and mates in the early evening. If the other bandicoots are anything to go by, the pig foot must have had a very short gestation. Baby bandicoots spend only about 12 days in their mother’s womb—the shortest time for any mammal—and they are also unique for being attached to their mother by a placentalike organ. The pig foot’s short gestation probably ended in a very short birth—which, for living bandicoots, is around 10 minutes. The tiny babies crept to their mother’s rear-facing pouch, and although there were eight teats in this furry pocket, there were no more than four babies in each litter. After the young had outgrown the pouch, the female left them in a grass nest until they were ready to follow her on forays for food in the warmth of the evening sun. 

What happened to the pig foot? The last known definite specimen was collected in 1901, and even long before this date, it was never considered to be a common species. We do know that it was hunted by Australian Aborigines for its meat, which was regarded as a delicacy, and its tail brush, which was sometimes worn as a decoration. The extinction of some of Australia’s other native animals has been blamed on Aborigines, but the pig-footed bandicoot coexisted with the Aborigines for thousands of years. The decline and extinction of this unique marsupial coincides with the spread of Europeans through Australia. For thousands of years, Aborigines practiced brush burning to clear land and encourage new plant growth. Many species of smaller marsupial profited from this because of the food it provided, not only in terms of fresh plant matter, but also in terms of the smaller animals that were forced out of hiding by the smoke and flames. With the arrival of Europeans, all this changed, as the Aborigines themselves were pushed toward extinction. The way the Aborigines managed the land ended, and any native animals that had previously benefited were faced with some tough times. As the Europeans swept aside the old Aboriginal ways, they replaced them with their own methods of taming the harsh land. They brought modern agriculture and a menagerie of domestic animals, including dogs, cats, foxes, sheep, goats, and cattle. To a seasoned predator, such as a cat or fox, the pig-footed bandicoot must have been a delightful morsel; however, hunting by introduced species was probably only a minor factor in their extinction. Agriculture probably had the greatest eff  ect on this species. Herds of sheep, goats, and cattle grazed the delicate plains of inland Australia, lands that simply could not tolerate the intensive chomping of countless mouths, not to mention the hordes of hooves, which churned the ground into a dust bowl. Not long after Europeans first settled Australia,  the pig-footed bandicoot joined the long roll call of extinct marsupials.

Source: Wikipedia

Rocky Mountain Locust (Melanoplus spretus)

In the late nineteenth century, much of the United States was a frontier where people sought to realize their American dream, and many of them headed to the vast prairies of this continent. The term prairie conjures up images of beautiful, undulating plains stretching as far as the eye can see, yet this image is not altogether accurate. In the winter, these plains get bitterly cold, and in the summer, they are blistering hot. Add to this an almost perpetual wind, and what you get is an unforgiving environment. As if these tough conditions weren’t enough for the settlers, they were also confronted with an insect that amassed in swarms of a gargantuan nature.

The Rocky Mountain locust was small by typical locust standards, with an adult body length of 20 to 35 mm, long wings that extended past the end of the abdomen, and the enlarged back legs common to most grasshoppers. What this insect lacked in individual size it more than made up for in the size of its aggregations. Locusts, for much of the time, live their lives in the same way as most other grasshoppers—going about their business without being much of a nuisance to anyone—but occasionally, their populations may become very dense, and this triggers a dramatic change. The locusts change color, their wings grow, and they start to amass in swarms.

The swarms formed by the Rocky Mountain locust were incredible and probably represent some of the biggest aggregations of any land animal that has ever existed. A swarm observed in Nebraska during the summer of 1874 was of staggering proportions. Dr. A. L. Child of the U.S. Signal Corps was charged with assessing just how big this swarm was, and to get an idea, he measured the speed of the locusts as they were fl  ying past and then telegraphed surrounding towns to get an idea of its extent. The swarm was estimated to be about 2,900 km long and 180 km wide. Observers in the Nebraskan towns over which this swarm passed reported that the gigantic cloud of insects obscured the sun and took five days to pass overhead. This begs the question of how many locusts there were in this enormous swarm. Estimates are as close as we’ll ever get, but it has been calculated that there must have been around 12 trillion insects in this aggregation. All these fl  uttering insects weighed somewhere in the region of 27 million tonnes, and if the desert locust of the Old World is anything to go by, then this swarm may have eaten its own weight in food every day just to sustain itself. Luckily, the Rocky Mountain locust was not a fussy eater—it would nibble a huge range of plants, and in the absence of foliage, it would munch bark, leather, laundry, dead animals, and even the wool off   a sheep’s back. As can be imagined, the multitude of mandibles left a trail of devastation, and between 1873 and 1877, the vast swarms of insects caused massive crop damage in Nebraska, Colorado, and some other states, estimated at around $200 million.

Around 30 years after these immense swarms left a trail of devastation in their wake, the Rocky Mountain locust mysteriously vanished. The reason behind the extinction of this insect has been speculated on for some time. Some experts have suggested that the species never became extinct and that the locust was actually the swarming phase of a species that can still be found today, a theory that has been shown to be incorrect. The likely explanation for the disappearance of this insect is that outside of its swarming periods, the locust retreated to the sheltered valleys of Wyoming and Montana, where the females laid their eggs in the fertile soil. These very same valleys attracted the attention of settlers, who saw their potential for agricultural endeavors, and with their horses and their plows, they turned the soil over and grazed their livestock on the nutritious grass. These actions destroyed the eggs and developing young of the insect, and around three decades after its swarms blotted out the sun, the Rocky Mountain locust was gone forever. 

Source: Wikipedia

Friday, October 7, 2011

Eskimo Curlew ( Numenius borealis)

The story of the Eskimo curlew is a sad tale of greed and senseless waste and a perfect example of how destructive our species can be. The Eskimo curlew was a small wading bird, no more than 30 cm long, with an elegant, 5-cm-long beak. Like the other curlew species, the Eskimo curlew had a distinctive, beautiful call, and the Inuit name for this bird,  pi-pi-pi-uk,  is an imitation of the sound they made on the wing and on the ground. 

The Eskimo curlew may have been a small bird, but it was one of the most accomplished globetrotters that has ever graced the skies. Like many other species of wading bird, this curlew spent its time between northern breeding grounds and southern wintering grounds. Traveling between the two was no mean feat, and the small birds had to embark on one of the most complex and dangerous migrations in the animal kingdom. As the short, northern summer ended and the curlew’s young had been reared, the birds took to wing for the beginning of an arduous and dangerous journey. Its migration took it in an immense clockwise circle, starting from the subarctic Canadian tundra, through the Western Hemisphere and east through Labrador, down through the Atlantic and across the southern Caribbean. The birds continued this epic journey until they reached their wintering grounds on the Argentinean Pampas. Some of the migrating birds went even further, eventually reaching Chile. The birds would spend a few months in South America until the spring returned to the north and the pull of hundreds of thousands of years of habitual behavior forced them into the air, en masse, for the return leg. The return to the breeding grounds took them through Texas, Kansas, Missouri, Iowa, and Nebraska. Completing such an arduous migration, nonstop, was an impossible task, so the enormous flock often alighted to refuel. The prairies of the Midwest were favored refueling stops, and the birds used their long bills to probe the soil for insect eggs, larvae, and pupae. Interestingly, it is thought that these refueling stops were heavily dependent on the Rocky Mountain locust, another extinct animal that once lived in unparalleled aggregations.  

The risks of this journey were varied and grave. The North Atlantic is ravaged by storms, and each year, many of the curlews were blown off   course to fi  nd themselves alone and hungry in the cold expanse of the North Atlantic. Some stragglers even found their way to Britain and the decks of Atlantic ships. It seems that the entire world population of Eskimo curlew lived and traveled as one immense flock, which, at its peak, probably numbered in the millions. There is protection in numbers, but each year, many individuals were undoubtedly picked off   by predators or perished due to exhaustion. These risks were intensified massively when Europeans started to settle North America. 

Because the curlew flew in such great flocks, the settlers called them prairie pigeons, recalling the enormous flocks of passenger pigeons that blotted out the sun in eastern North America. There are accounts of an Eskimo curlew flock of 1860 measuring more than 1 km long and wide. Any animal that is edible and exists in huge numbers quickly attracts the attention of hunters, and unfortunately, the curlew was both of these things. The curlew may have seemed numerous, but the enormous flock the hunters preyed on was the entire global population of this bird, and hunting quickly took its toll. During the birds’ feeding stops on their long route north, the hunters would close in on the flock and, sensing danger, the birds would take to the wing, an effective defense against land predators and birds of prey but completely useless against shotguns. The birds were so tightly spaced as they left the ground that a single blast from a shotgun, with its wide spread of shot, could easily kill 15 to 20 individuals. The birds were shot in such huge numbers that countless numbers of them were simply left to rot in big piles. The rest were taken away, piled high on horse-pulled carts. Such senseless slaughter of the Eskimo curlew on its northbound journey was bad enough, but it was not long before the hunters turned their attention to the birds’ breeding grounds. 

During the northern summer, in anticipation of their long migration south, the birds fed on the swarms of insects that plague the tundra in the fleeting warmth, and as a result, they grew very fat. Hunters called these well-fed birds “doughbirds,” and even these were not safe. The hunters would fi  nd their roosting grounds and slaughter them under the cover of darkness, using lanterns to dazzle them and sticks to club them. The fattened birds that survived took to the wing for the start of their migration, but gales would often blow them into New England, and this was the signal for every man with a gun to come out and harvest the poor animals. In the 1830s and 1840s, the birds were blown off   course and ended up in Nantucket. The populace killed the birds so mercilessly that the island’s supply of powder and shot ran dry, interrupting the slaughter.  Under such intense hunting pressure, the Eskimo curlew was doomed. In 1900, Paul Hoagland was hunting with his father near Clarks, Nebraska. They scared 70 Eskimo curlews into taking flight and followed them to a newly plowed fi  eld. They killed 34 of the birds with four shots. In 1911, the same man came across eight of the birds, and he killed seven of them. Reduced from an enormous flock covering an area equivalent to around 38 football fi  elds, this sorry collection of birds was the last to be seen in Nebraska. Since 1900, 20 Eskimo curlews have been collected by ornithologists, and in 1964, the last confi  rmed individual of this species was shot in Barbados. Lonely individuals may still plow the old migration routes, but it is very likely this species is gone for good.

Source: Wikipedia

Gastric Brooding Frog (Rheobatrachus silus)

Another victim of the amphibian disaster was a fascinating little frog from Australia that was only discovered in 1973, yet by 1981, it had vanished without a trace. 

The gastric-brooding frog was a small species; females were around 5 cm long, while males were smaller, at approximately 4 cm. It lived in forest streams and rocky pools, and for much of the time, it would hide beneath rocks on the bed of these water bodies, but when it left these rocky refuges and moved out into the fast-?owing water, it showed itself to be a very accomplished swimmer. Its powerful hind-limbs terminated in feet that were almost completely webbed, and these were used with good effect to propel the frog through the water. The big, protruding eyes of this frog were positioned well on top of its head, and this allowed it to survey what was going on in the air and on land, while its body was out of sight beneath the water. Although it was very well adapted to an aquatic existence, the gastric brooding frog would often leave the water to hunt or to seek out a new stretch of stream. 

Its favored prey were small invertebrates, such as insects, but unlike many types of frog, the gastric brooder did not have a long, sticky tongue to secure its prey; instead, it waited until its food was within range and simply lunged at it with an open mouth. With its prey partially trapped, the frog would shove the rest of the victim’s body into its mouth using its forelimbs. Even though this frog was a capable predator, it was very small, and it was a tasty morsel for a range of predators. Herons and eels were partial to this amphibian, but it did have a useful defense if it was grabbed by one of these animals: mucus. All amphibians have skin glands that produce mucus to keep their skin moist as well as for protection. The gastric brooder could produce lots of very slippery mucus, which made it very hard for a predator to get a good grip. 

In most respects, the gastric-brooding frog was like most other frogs, but what set it apart was the way it reproduced. Mating was never observed in this species, but it is known that the female laid between 26 and 40 eggs and that these were then fertilized by the male. Again, this is the normal amphibian approach when it comes to breeding as fertilization in all these animals is external. It is not completely clear what happened next as it was never actually seen, but at some point after the eggs were fertilized, either when they were still eggs or when they had hatched into tiny tadpoles, the female swallowed as many of her offspring as she could. To the uninitiated, this may have looked like maternal cannibalism, but in fact, this was part of this frog’s unique reproductive strategy. The eggs or small tadpoles slipped down their mother’s throat and ended up in her stomach, and this is where they grew. In all animals, the stomach is the organ that plays a major role in digestion. Cells in the lining of the stomach produce very strong acid that breaks down food into its component fats, proteins, and carbohydrates so that enzymes can begin their digestive work. This harsh, acidic environment is hardly ideal for developing offspring, but over millions of years, these frogs evolved a couple of tricks that turned the stomach into a snug little capsule for their developing brood. It seems that the eggs and the tadpoles of this frog secreted a type of chemical known as a prostaglandin. This chemical blocked the cells of the stomach lining from secreting acid, and the walls of the stomach thinned. The young frogs turned the stomach into a cozy crèche. After six to seven weeks of developing in their mother’s alimentary canal, 6 to 25 tiny but fully developed frog lets clambered out of their mother’s mouth to begin their own life in the big wide world. Throughout this whole brooding period, with her stomach effectively shut down, the female frog was unable to feed, so after the departure of her young, her first consideration was probably finding some food. 

In fewer than 10 years after its discovery, the gastric-brooding frog disappeared. Extensive searches of the mountain streams in the early 1980s failed to turn up a single specimen. When the species was first discovered in 1973, it was considered to be quite common, but by 1981, not a single specimen was to be found—it was as though it had been spirited away. Like the golden toad of Costa Rica, exactly what happened to the gastric-brooding frog is unknown, but there have been several explanations, some of which are more plausible than others. Pollution of the mountain streams by logging companies and gold panners has been cited as a reason for the disappearance of this species, but tests on the stream water failed to show any significant pollution. Habitat destruction has also been mentioned, but the areas where this frog was found have been pretty well protected. With pollution and habitat destruction largely ruled out, we arrive at the specter of disease. The chytrid fungus has caused the deaths of amphibians all over the world. The fungus latches on to the body of an amphibian and takes root in its skin. The fungus forms cysts within the deeper layers of the skin and breaks down keratin, a protein in the cuticle of many vertebrates, including adult frogs and toads. The skin of an amphibian infected with this fungus begins to break down, and in severe cases, the disease can eat right into the deeper tissues. In these cases, digits, and even limbs, can be eaten away. This in itself is not fatal, but the ability of the skin to transport gases and prevent the entry of other harmful micro-organisms is probably impaired, and the victim dies a slow and probably very painful death.

Source: Wikipedia