The largest herds in the animal world

Some birds, fish, mammals, and insects can congregate in large flocks of millions to trillions.

Bird

In early 2020, ornithologist Noah Strycker from Brook University in the US found himself walking among thousands of bearded penguins on Elephant Island, a remote ice-covered land off the coast of Antarctica. . He's there to do a survey of the penguin colony, which hasn't been properly surveyed since 1970.

The final survey by Strycker and his colleagues found that strappy penguins actually form one of the largest bird colonies in the world, centered around 2 million in some locations like the South Sandwich Islands. This discovery prompted Strycker to answer an even more ambitious question: what is the largest group of animals ever recorded on Earth?

A flock of strappy penguins on Elephant Island in Antarctica. Photo: Wolfgang Kaehler

Strycker embarks on his mission and finds that the South Sandwich penguins are easily "overtaken" by another species of bird called the red-billed Quelea, which lives on the savannas of sub-Saharan Africa.

"They congregate in very large herds with millions, tens of millions and possibly hundreds of millions," Strycker said. "I think they are the most abundant bird in the world."

Quelea is so red-billed that observers say it takes five hours for a swarm to fly overhead. However, they are not yet the largest flock of birds.

"There are stories of swarms of passenger pigeons flying over observers' heads for hours or days. It's crazy!" Strycker added. A gathering in 1866 recorded as spreading 1.6 km wide and 482 km long, is estimated to contain about 3.5 billion pigeons, based on counts per square mile and extrapolation to size. herd size. Today, passenger pigeons have been hunted to the point of extinction.

Fish

Moving from the sky high into the depths of the ocean, there are records of a fish species - specifically the Atlantic herring - gathering in schools of more than 4 billion, far ahead of the best "candidate". before that was the passenger pigeon.

Mammal

The mammals don't reach as large swarms as the Atlantic herring, but are worth mentioning. These include the jumping antelope and wildebeest in southern Africa. In the past, they have gathered in flocks of more than 1 million, marching across the grasslands for weeks.

But most impressive is the Mexican tailed bat (Tadarida brasiliensis). In Texas, there is a single cave that is home to more than 20 million of these bats. When they left the burrow to feed, they formed a giant rippling cloud in the sky.

A herd of wildebeest with a few zebras during the migration season inside the Masai Mara reserve in Kenya. Photo: AfriPics

Grasshopper

The record for the largest swarm in the animal world belongs to grasshoppers. In East Africa in early 2020, a cloud of desert locusts swept across the sky, spanning thousands of square kilometers.

"It was like a black blanket covering the sky, so dense that it was difficult to see the clouds," said researcher Emily Kimathi at the Center for Insect Physiology and Ecology in Kenya.

That particular event was the largest swarm observed in the Horn of Africa in 25 years. Experts estimate that they congregate at a density of about 50 million individuals per square kilometer, meaning that a single swarm of locusts would contain about 200 billion. Desert locusts are known for their ability to reproduce very quickly, able to multiply 20-fold in a three-month period.

A man tries to drive away a swarm of desert locusts at a farm near the town of Nanyuki in Laikipia, Kenya.

200 billion is a staggering number, but data from the past show that locust swarms can outnumber locusts under ideal environmental conditions. In 1875, a meteorologist named Albert Child was stunned to see grasshoppers soar through the sky in a giant swarm that covered much of the western United States. This species is the Rocky Mountain locust, and Albert estimates that it covers an area of ​​512,800 square kilometers.

This historic event is also known today as "Albert's locusts". Based on meteorologists' estimates, their number could be as high as 3.5 trillion. This is believed to be the largest number of animals in a herd that humans have ever recorded.

Like the passenger pigeon, the Rocky Mountain locust is now extinct, with the last living specimen observed in 1902 in southern Canada, but their historic flight remains a record that is very difficult to break. broken.