Please send your good wildlife photos if you got ’em. Otherwise, we’ll run out of contributions before Friday, and this feature will end.
Today we have a photo-and-text story by Athayde Tonhasca Júnior. His words are indented, and you can enlarge the photos by clicking on them.
How the mighty have fallen
“And they shall cover the face of the earth, that one cannot be able to see the earth: and they shall eat the residue of that which is escaped, which remaineth unto you from the hail, and shall eat every tree which groweth for you out of the field: And they shall fill thy houses, and the houses of all thy servants…” Exodus 10:5-6, King James Version.
The Bible never sounded as prescient to Americans and Canadians as in the years 1873-1877. On summer days, farmers in the prairie regions watched with alarm and hopelessness as black clouds formed in the foothills of the Rocky Mountains. These clouds would eventually grow and descend to lower ground, hiding the sun in the middle of the day and filling the air with the sound of millions of scissors snipping away. The clouds contained no rain, hail or sand: they were made of locusts, billions of them (locusts are gregarious forms of grasshoppers). In 1875, Dr Albert Child of the U.S. Signal Corps timed a swarm flying over Plattsmouth, Nebraska, for five days straight, and telegraphed nearby towns for similar sightings. Dr Child estimated the swarm to be about 3,000 km long and 180 km wide (Second Report of the U.S. Entomological Commission, 1880). That’s equivalent to 27 million tonnes of moving biomass.
A swarm of locusts in Madagascar, tiny in comparison to the ones befalling 1800’s North America © Michel Lecoq, Wikimedia commons.
Inevitably the locusts would come down to earth, devouring any plant in sight in a few hours; the farmers’ hard labour, mainly in the form of maize and wheat crops, would be wiped out. Here’s how Laura Ingalls Wilder (1867-1957), of Little House on the Prairie fame, described her childhood experience with locusts in Minnesota in 1874:
“Their thin, large wings gleamed and glittered. The rasping whirring of their wings filled the whole air and they hit the ground and the house with the noise of a hailstorm. Laura tried to beat them off. Their claws clung to her skin and her dress. They looked at her with bulging eyes, turning their heads this way and that… Grasshoppers covered the ground, there was not one bare bit to step on. Laura had to step on grasshoppers and they smashed squirming and slimy under her feet … ‘The wheat!’ Pa shouted.” (On the Banks of Plum Creek, 1937).
The protagonist of such a nightmare was the Rocky Mountain locust (Melanoplus spretus).
The Rocky Mountain locust, a feeding juggernaut © Julius Bien (1826-1909), Wikimedia Commons.
Locust outbreaks were nothing new, but Americans and Canadians were in for an onslaught. These racing feeding machines had a devastating impact: vast areas of agricultural land became barren, and many families gave up farming and fled to cities; in Canada, the lack of fresh vegetables caused outbreaks of scurvy, a disease caused by vitamin C deficiency; in both countries, army troops were mobilized to feed thousands of families. In 1877, the Minnesota Legislature passed the ‘grasshopper draft’: all able-bodied men from 12 to 65 years old should gather locusts for at least one day: failure to comply could result in fines or 10 days in jail. The law made no difference to the Rocky Mountain locust.
Kansas farmers battling locusts © Henry Worrall (1825-1902), Wikimedia Commons.
But then, after the appalling rapacious raids in the late 1800s, the Rocky Mountain locust started to wane. Swarms became intermittent and smaller, and by the turn of the century there were no more locusts to be seen. The last two confirmed specimens were collected in Canada in 1902. In less than 30 years since Dr Albert Child reported the entomological version of Attila the Hun crossing the skies of Nebraska, the Rocky Mountain locust had disappeared from the face of the Earth. Nowadays only a few pinned specimens can be found in museum collections.
The abrupt extinction of the Rocky Mountain locust is one of greatest ecological puzzles of all times. Many explanations have been proposed, but today’s most accepted theory is that humans unknowingly bumped it off. Which is a great irony, considering the futile efforts of farmers, scientists and governments in killing it. During their grasshopper form, that is, before multiplying, swarming and making a nuisance of themselves, Rocky Mountain locusts gathered along a few river valleys where females laid their eggs in the soil. These fertile riparian habitats attracted settlers as well, who little by little altered the newly occupied pristine habitats by turning the soil over with their ploughs, and by bringing in herds of cows and horses to feed on the nutritious grass – who would trample and churn the soil while they were at it. These disturbances destroyed the insect’s eggs and immature forms developing underground, quickly sealing the fate of the Rocky Mountain locust.
Another animal once blackened the American skies with its sheer numbers: the passenger pigeon (Ectopistes migratorius). This migrating pigeon was believed to be the most abundant bird in North America, numbering from 3 to 5 billion. French-American artist, naturalist and ornithologist John James Audubon (1785-1851) described a passenger pigeon migration in 1813:
“The air was literally filled with Pigeons; the light of noon-day was obscured as by an eclipse; the dung fell in spots, not unlike melting flakes of snow, and the continued buzz of wings had a tendency to lull my senses to repose…. Before sunset I reached Louisville, distant from Hardensburgh fifty-five miles. The Pigeons were still passing in undiminished numbers and continued to do so for three days in succession”.
Passenger pigeon hunt in Louisiana © Smith Bennett, Illustrated Sporting and Dramatic News, 1875. Wikimedia Commons.
Despite its mindboggling numbers, the passenger pigeon was no match for the war waged against it – relentless hunting on an industrial scale and destruction of its habitats increasingly depleted its populations. By the 1850s, alarm bells started to go off, but with no practical results. In 1857, a bill was presented to the Ohio State Legislature for the passenger pigeon’s protection, but a Select Committee ruled against it, noting that the bird was “Wonderfully prolific… no ordinary destruction can lessen them”. By the 1900s, the pigeon had disappeared in the wild, and only a few specimens hung on in captivity. From 1909 to 1912, the American Ornithologists’ Union offered US$1,500 to anyone reporting a nesting colony of passenger pigeons, but the reward was never collected. In 1914, Martha, the last known passenger pigeon, died at the Cincinnati Zoo. She was about 29 years old and had never laid a fertile egg.
Martha in 1912. After her death, her body was mounted in a display case with the notation: “MARTHA, last of her species, died at 1 p.m., 1 September 1914, age 29, in the Cincinnati Zoological Garden. EXTINCT” © Enno Meyer, Wikimedia Commons.
In On the Origin of Species, Charles Darwin noted a relationship between species abundance and the size of their geographic range, and suggested that these factors were important for species’ success: “Who can explain why one species ranges widely and is very numerous, and why another allied species has a narrow range and is rare? Yet these relations are of the highest importance, for they determine the present welfare, and, as I believe, the future success and modification of every inhabitant of this world.”
Indeed, low abundance and restricted range (both expressions of rarity) are considered the main factors in extinction risk, and are the leading criteria for Red List species assessments by The International Union for Conservation of Nature. And yet, two species once widespread and unimaginably abundant, are gone forever.
The Rocky Mountain locust and passenger pigeon tales suggest any organism could tip over into oblivion once it is pushed too far. It could happen to a species near you.