WORLD’S MOST NUMEROUS BIRDS
Red-billed quelea (Quelea quelea) is the most abundant bird in the world today. According to Crook and Ward’s estimate of 1968, the population of these sociable seed-eating African weaverbirds was at 1-10,000 million, which was believed to be highly exaggerated. Their estimate was based on reported kills, which the farmers often made to save their crops. A more recent estimate by Clive Elliott is thought to be more accurate which puts the population at 1,500 million. This is based on breeding reports and a continent-wide adult breeding population.
One of the main reasons for such a large number is high rate of breeding success. Different populations have different breeding seasons throughout the continent so there is no seasonal peak population level overall. Birds breed twice a year, and in exceptional cases three times. According to Ward on an average 2.3 fledged chicks per pair are produced from an average clutch of three eggs.
The range of the bird covers more than three-fourth of the African continent, from Senegal in extreme west to Sudan in extreme east, and the savannah regions from Sudan south to the Transvaal in South Africa.
Size of the population
The magnitude of the population can well be understood by the fact that the night roosts are so large and dense that sometimes whole tree collapses under the weight of a 20 g bird. It is said that one roost in Sudan contained about 32 million individuals. The largest seen by Clive Elliott contained about four million birds at Tsavo in Kenya. According to experts, at dawn when the flocks leave their roosts they might temporarily be containing between 100,000 to 125,000 birds but these would soon break up into much smaller groups to feed.
Also known as diochs, the genus of these birds contains three species and there are three races also of red-billed quelea. They are so plentiful in the continent that on an average more than 500 birds build nests on one tree.
Also world’s most significant pest
It is not only the world’s most abundant bird, but also the world’s most significant pest in agriculture. The crops, which are attacked most by these ‘feathered locusts’, are wheat, sorghum, millet, and rice. According to an estimate a continent-wide damage caused by them is about one per cent of Africa’s total cereal production, costing about 3 crores dollars (30 million dollars). If we see the total loss, it is not of very high, but the destruction is so frequent and consequently, it spells disaster for thousands of subsistence farmers who lose an entire year’s food supply.
Red-billed queleas migrate according to regional fluctuations in food supplies. Bulk of their diet is of smaller wild grass seeds, and even in years of severe damage only 20 percent of food consumption is of cultivated cereals. When there is shortage of their natural food, usually at the end of dry seasons, the real trouble starts. Huge flocks begin their search for new feeding grounds, for which they wander over vast areas and settle down where they find possibility of finding food.
On an average each bird consumes about 4 gm. of food per day and dislodges about 8 gm. so its total destructive power is 12 gm per individual per day. This quantity seems very meager, but since they feed, roost and nest in flocks they destroy whole area wherever they settle down to feed.
Killing of birds has been the main method to control their population but, it too has not solved the problem. The reason is that queleas often breed in inaccessible areas.
Despite this flame-throwers, dynamite bombs and aerial spraying of poisons and detergents are used to kill queleas, which kill about 100 crores (1,000 million) individuals every year, but 50 crores (500 million) still survive, if we go by Clive Elliott’s estimate of bird’s population.
Passenger pigeon : lost forever
Passenger pigeon (Ectopistes migratorius) – These birds were once the most numerous birds ever. Their number was so high that no one could had ever thought that the total extermination of the bird was possible, still it became extinct in the wild by the beginning of the 20th century and the last bird, named “Martha” died on 1st September 1914 at 1 pm (Eastern Standard Time) in Cincinnati Zoo, Ohio, USA. It was hatched at the zoo and lived for 29 years.
Passenger pigeons were North American birds whose number was so large that it was literally impossible to give an accurate estimate of the population, but whatever reports are available they suggest the number might have been between 500 to 1,000 crores (5,000 to 10,000 million) in the first half of the 19th century. Even the most conservative estimates claim there used to be ‘hundreds of millions’ of birds. It is estimated that at the time of Columbus there were only about 300 crores (3,000 million) birds. The great success in multiplying is attributed largely to farming.
Though American Indians had long known about the tasty meat of these birds, they never killed more birds than they could eat because they respected nature. Besides, they never hunted during the nesting season. On the other hand, the white settlers had no respect for laws of nature, and slaughtered the birds just for fun and pleasure.
Passenger pigeons bred throughout the northern forests from Manitoba to Nova Scotia and South to Kansas and West Virginia. They wintered from Arkansas and North Carolina south to central Texas and northern Florida.
In the beginning of 19th century, an American zoologist Alexander Wilson saw a flock of passenger pigeons, which numbered, according to his rough estimate, around 2,230,272,000 birds. His calculation was that if each bird ate 1/2pt of corns a day their daily diet would be of 17,424,000 bushels (a dry measure of eight gallons). This single massive flock would have outnumbered ten to one all the birds in the British Isles as once estimated by James Fisher. There were many such flocks. Another zoologist estimated that at least 136,000,000 pigeons built their nests in a forest, area totaling about 2,200 sq km. The famous artist and author, Audubon (q.v.) saw one flock near Louisville in which he estimated 1,115,136,000 birds.
It is claimed that pigeon flocks, 3-4 miles (5-6 km) wide and up to 300 miles (500 km) long, could be seen passing over southern USA on their migration flights. Their passage could darken the sky for hours, and sometimes days, at a time, it was as if the dusk had fallen, and when they stopped for the night, there were not enough twigs in the forest for perches and pigeons would sit in several rows one on top of the other. Sometimes even thick boughs broke under their weight, although individual weight of the birds was not more than 250 grams.
These birds were killed in such a large number that by the beginning of the 20th century passenger pigeons became so scarce that in 1909 a prize of 1,500 dollars was offered to a person who could show its nest in the wild. Most astonishing fact is that this situation came in just 25 to 30 years.
According to the available accounts from reliable people, the flocks of birds were so large that the people brought them down with sticks, stones and oars. There was a situation, when thousands of birds could be seen lying dead on the ground, but people went on killing more and more. Farmers killed them with poles, boards and caught them in nets. Their modus operandi was that, people used to wait for pigeons’ migration and got prepared for it with stocks of stones, and nets to kill them. Barrels were made ready for salting of meat. Countless barrels used to be shipped to the big cities where they often rotted on the sidewalks for want of buyers.
Connoisseurs soon discovered the best and fattest meat was that of young birds not yet able to fly. To earn huge profits expeditions set out for pigeons’ nesting places. Nests were knocked down with poles and the fledglings chocked. If the poles were not long enough, the hunters felled the trees.
Killing of birds in this way was not the extreme of the game. Real annihilation started when ‘professionals’ appeared on the scene and slaughter began in an organized manner. Special scouts sought out the pigeons, and then telegraphed the whereabouts of the flock. Detachments of hunters would be sent there armed with rifles. Now the fate of these harmless birds was sealed. The magnitude of the extermination can well be guessed by the fact that in a single hunting season about 15 lakh (one and a half million) of them were shot in the state of Michigan alone.
Killing was on such a large scale that by 1880 a situation came when only few small flocks could be seen migrating about the country, and by 1902 they were almost completely destroyed. In 1909, a prize was offered to the person who could locate the bird’s single nest in the wild. Many tried their luck, but the prize was never claimed.
Last thirty years (1880 onwards) of the species’ life, proved very difficult. The extinction of such a numerous species in such a short span is probably the most dramatic decline of all time. Experts are not ready to believe that the bird could have been totally exterminated just by hunting. For them eventual disappearance remains puzzling because the last few million birds went away with such suddenness.
Some experts believe that some deadly disease or migratory disaster might have contributed for the demise of birds, while others have different theory, according to which the bird’s breeding success might have been dependent on its gregarious habits. Therefore, the reproductive rate could have dropped with the size of the colonies, some of which were several square kilometers in extent with a hundred or more nests in a single tree. Due to roosting and perching of birds damage to trees was alarming both chemically and physically.
Whatever might have been the reason for the extinction of the species, the fact remains that the bird has gone forever. Now we can do nothing except documenting the facts – the last huge nesting took place in 1878. This was the time when vast forestland, which used to be the habitat of these birds, was being converted into farmland. The last well-verified shooting took place in 1899 in Wisconsin.
House sparrow and common starling
In 1951 Fisher proposed the common starling (Sturnus vulgaris) and House sparrow (Passer domesticus) as the world’s most abundant landbirds, but it has been pointed out that while their distribution is exceedingly wide their occurrence is relatively localized. The house sparrow is undoubtedly the world’s most successful introduced species and already occupies over two-thirds of the world’s land surface. While not as widespread as house sparrow, the starling is equally adaptable and assembles in impressively vast numbers.
According to Fisher the little auk (Alle alle) was the most numerous seabirds on earth, but the fact is they are notoriously difficult to census. Other people suggested several other species like puffin, guillemot and crested auklets to be numbering several millions of pairs. First there is no proof to substantiate these claims and secondly, there is tendency to overestimate the populations of colonial species.
In Darwin’s view fulmar (fulmarus glacialis) was the most abundant bird in the world. Experts feel probably he was misled by his own encounters with this bird at sea in the North Atlantic, where large colonies can be seen, but the fact is in no way can fulmar’s population be compared with the abundance of other seabirds.
Some people claim Wilson’s storm petrel (Oceanites oceanicus) to be the most abundant bird in the world. Again such a notion seems fanciful, though this species could be the most abundant seabird with an estimated population of some hundreds of millions. This very small 18-19 cm bird is rarely seen in large numbers but is fond of following ships.
America’s most numerous landbird
America’s most numerous landbird is probably the Redwinged blackbird ( Agelaius phoeniceus), which has been well-censused because of the great agricultural damage it inflicts. A US Fish and Wildlife Service roost survey during the winter of 1976/77 in Kentucky and Tennessee revealed 25 roosts containing over one million birds in each and a total of 47 million birds for these two states alone!!!!
Britain’s most abundant breeding bird
Britain’s most numerous bird is the wren (Troglodytes troglodytes) with a population of 15-20 million. The common wren is the only Old world representative of an extremely common New World family. It is very widespread species with five races in Britain and seven in North America, where it is known as the winter wren.