Aerial photo taken on June 7, 2021 shows wild Asian elephants napping in Jinning District of Kunming, southwest China’s Yunnan Province.
Credit: © Xinhua/Alamy Images

A wild elephant herd has captured global attention and baffled, well, everyone. Fifteen elephants, including three calves, have been on a mysterious trek across their native China. Traveling for over a year, the migration has taken them more than 300 miles (500 kilometers) from home. Their natural habitat is thought to be the Mengyangzi Nature Reserve in Xishuangbanna, Yunnan. Reserves are areas of land set aside to protect the habitats of elephants and other wild animals. China only has about 300 wild elephants. Most live in the south of the Yunnan province.

The traveling herd gained fame in China despite trampling crops, damaging property, and occasionally poking a trunk through someone’s window. The elephant’s padded feet enable them to walk and run with surprisingly little noise. Elephants normally walk at a speed of 3 to 6 miles (5 to 10 kilometers) an hour. When making a long journey, a family walks at about 10 miles (16 kilometers) an hour.

The elephants might have been looking for a new habitat, though they wouldn’t find one among millions in the city Kunming. Paths were cleared and food was provided as towns moved to protect the elephants.

Safety is a high priority for the endangered Asian elephant. Local government launched drones and mobilized hundreds of people to protect the herd’s migration. People attempted to steer the elephants in the southwest direction, back toward the reserve. However, the herd may have decided to head home all on their own.

Elephants are extremely strong and highly intelligent. There are two kinds of elephants, African elephants and Asian elephants, also known as Indian elephants. Asian elephants live only in southern and southeastern Asia. They are found in forests and jungles of Cambodia, China, India, Indonesia, Malaysia, Myanmar, Sri Lanka, Thailand, and Vietnam.

Today, wildlife experts agree that elephants are in great danger and need human protection to survive. The number of wild elephants has greatly declined because people kill elephants for their ivory tusks. Farming and industry threaten the natural resources needed by elephants to survive. In Asia, human population growth and habitat destruction have severely reduced the number of wild elephants. Scientists estimate that only about 40,000 Asian elephants survive in the wild.

An adult Asian bull stands from 9 to 101/2 feet (2.7 to 3.2 meters) tall at the shoulder and weighs up to 8,000 pounds (3,600 kilograms). Asian cows stand about 8 feet (2.4 meters) tall and weigh about 6,600 pounds (3,000 kilograms).

Most Asian elephants have light gray skin and may have pink or white spots. Most Asian bulls have tusks that grow from 4 to 5 feet (1.2 to 1.5 meters) long. However, some Asian males, called makhnas, have no tusks, and many Asian females have none. Other Asian females have extremely short tusks called tushes.

January 19, 2018

How and when did people first reach the Americas? It is generally agreed that humans arrived in the Western Hemisphere at least 15,000 years ago. They got there by crossing Beringia, a land bridge that once connected Asia and North America. (Beringia takes its name from the Bering Strait and Sea that now cover the former land bridge.) The details of this human movement have long been a mystery. Recently, however, ancient DNA found in Alaska has helped scientists learn about the timing and circumstances of the migration.

University of Alaska Fairbanks professors Ben Potter and Josh Reuther excavate the remains of two ancient infants along the Upward Sun River in Alaska. Credit: © Ben Potter, University of Alaska Fairbanks

In 2011, a team of archaeologists discovered the bones of two female infants along the Upward Sun River in Alaska. One was an infant who died a few months after birth. The other was a newborn or late-term fetus. The archaeologists determined that the infants died about 11,500 years ago. After the Upward Sun River infants died, their bodies were laid atop a bed of red ocher surrounded by antler points. Only small fragments of DNA from the younger infant were available to study. However, scientists were able to reconstruct the genome (the entire set of chemical instructions that control heredity in a human being) of the older infant.

This scientific illustration shows the ancient Upward Sun River camp in what is now interior Alaska. Credit: © Eric S. Carlson/Ben A. Potter/University of Alaska Fairbanks

Previous studies have shown that Native Americans are descended from one of two ancestral groups. The northern group produced most of the indigenous (native) people of Alaska and upper Canada. A southern group produced most of the indigenous people of the lower United States, Mexico, and Central and South America. The genome of the older infant revealed that she came from a very early group of Native Americans who were the ancestors of both the northern and southern indigenous groups. These original people are now known as the Ancient Beringians. The scientists’ work represents the first reconstruction of an Ancient Beringian genome. It provides key evidence to the theory that all living Native Americans are originally descended from the same group of people.

Despite the fact that the Upward Sun River infants shared a grave and seem to have been from the same community, their DNA shows a great deal of variation. This variation supports what is known as the Beringian Standstill hypothesis, which suggests that ancient Siberians entered Beringia and stayed there for thousands of years before they entered the Americas. This hypothesis proposes that ice age glaciers blocked their migration until about 15,000 years ago, when the glaciers began to melt and retreat. According to the Standstill hypothesis, much genetic mixing would have occurred in Beringia before movement into the Americas began. This helps explain why the two infants’ DNA shows such variation.

The remains of the Upward Sun River infants have shed much light on the migration of the Ancient Beringians. However, more ancient DNA must be gathered and studied before the Beringian Standstill hypothesis can be proven true. There are still many details about the populating of the Americas that remain a mystery.

February 17, 2017

Earlier in February, scientists learned that the dorado catfish (also known as the dourada or gilded catfish) of South America has the longest migration of any freshwater fish. These large catfish live in the Amazon River Basin, and their migratory path takes them from the foothills of the Andes Mountains to the mouth of the Amazon River on the Atlantic Ocean, and then back again—a trip of more than 7,200 miles (11,600 kilometers)!

The long-traveling dorado catfish navigates the waters of the Amazon River Basin throughout its life. Credit: © Michael Goulding, Wildlife Conservation Society

Catfish have pairs of fleshy whiskerlike growths near the mouth. These growths, called barbels, resemble the whiskers of a cat. Catfish differ from most other fish in that they do not have scales. Catfish live in many different places around the world, and they come in a variety of shapes and sizes. The dorado catfish (Brachyplatystoma rousseauxii) is just one of several different species (kinds) of catfish that live in the Amazon River and its many tributaries. Dorados can grow beyond 6 feet (2 meters) in length and are grouped with other “goliath” catfish, so named because of their large proportions. Their lengthy migration has long been suspected, but only recently have the details of their epic migratory journey been confirmed. A study of the distribution of larvae, juveniles, and mature dorados showed where the fish tend to be at different stages of life. The study, published in the journal Scientific Reports, was a group effort led by the Wildlife Conservation Society’s Amazon Waters Initiative. Ronaldo Barthem from the Museu Paraense Emílio Goeldi in Brazil led the research team.

This map shows the remarkable migration of the dorado catfish through the Amazon River Basin. Credit: © Wildlife Conservation Society

Barthem and his team found that dorados spawn in the Andes waters of Colombia, Ecuador, Peru, and Bolivia. The larvae then begin a precarious journey downriver, finding their way through such tributaries as the Madeira, the Marañón, and the Rio Negro—all major rivers themselves—to the mighty Amazon itself. The young catfish grow as they travel eastward, following the currents across Brazil to the eventual end of the Amazon north of Marajó Island on the Atlantic coast. There the fish gather in the vast and organically rich waters of the estuary, feeding, growing, and maturing. After a couple years, the fish get the urge to travel back upriver, taking the long swim—another two years—back to the spawning grounds where the life cycle begins again.

Dorados also live in the rivers of Guyana and Venezuela, and they are an important food fish for people throughout the Amazon Basin. Dorado catfish are not an endangered species, but their migration becomes increasingly difficult each year because of damming, deforestation, mining, and pollution.

Salmon and eels are other fish known for their long migrations, but their routes combine saltwater and freshwater routes and still fall short of the long swim of el dorado.

September 10, 2014

Climate change will imperil nearly half the bird species in the United States and Canada by the end of the century, according to a study published September 9 by the National Audubon Society. The seven-year study compared changes in climate to shifting patterns in bird migration.

Global warming is an ongoing rise in Earth’s average surface temperature thought to result from human activities. As the planet warms, climates change, often causing a particular set of climate conditions to shift toward the poles. Thus, as conditions in the United States and Canada shift northward, birds and other living things will no longer be able to thrive over much of their traditional ranges. It is unclear, however, how successfully bird species will be able to follow shifting climates into new areas.

The common loon, also called the great northern diver, is a North American water bird with a sleek body for swimming and diving. Scientists are concerned that, as climate change shifts the traditional range of loons northwards, the bird will be unable to adapt to its new range. Many other birds of the United States and Canada may be in the same predicament (World Book illustration by Athos Menaboni).

The bald eagle, for example, is projected by the report to lose about 75 percent of its summer breeding range by 2080. Some of this range may be recovered as new areas become open to the eagle, but it is unclear whether eagles will be able to find the resources they need to survive in these places. Likewise, the range of the common loon is shifting northward, meaning that Minnesota’s state bird will likely not be found within that state by 2080.

Additional World Book articles:

• Bird (Research guide)
• Climate
• Why Species Are Important (a Special report)

January 20, 2014

The long-held theory that birds fly in a V formation to conserve energy has been confirmed scientifically by researchers tracking migrating northern bald ibises. The researchers found that each bird beyond the first adjusts its position and the beating of its wings to get a helpful lift from the bird in front. For the study, published in the journal Nature, the scientists attached sophisticated sensors to the birds.

Flocks of many larger birds, including geese, ducks, and pelicans, adopt V-shaped formations for long migration flights. Scientists have long suspected that this helps them save energy, but the study provided the first scientific confirmation.

Some of the scientists behind the study were involved in a program to release captive-bred ibises into the wild. They trained the birds to migrate by getting them to follow a lightweight aircraft. The scientists attached a sensor pack to each bird for a 600-mile (965-kilometer) migration flight from Austria to Tuscany. Each pack included an accelerometer, a gyroscope, a magnetometer, and an extremely sensitive Global Positioning System (GPS) unit. This setup enabled the scientists to track each bird’s speed, position, and wing rhythm in detail. The scientists then compared the data to models developed using aerodynamics, the study of movement through air and other fluids.

Canada geese and other birds that migrate in a flock fly in a V formation to help save energy on long flights. (© Chase Swift)

The results showed that each bird positioned itself to take advantage of vortices (swirls of air) generated by the wings of the bird in front. The vortices are created when the wings push down the air. In the process, other air rises to the right and left of the wings. The birds positioned themselves to get the maximum upward push from these swirls. Likewise, each bird timed its wing beats to take the greatest advantage of vortices, adjusting its rhythm whenever its position changed.

Taking advantage of such vortices makes each bird’s flight slightly easier. Such energy savings may be small, but they can add up over long migrations. The birds in front gains no advantage, but the ibises in the study changed leaders from time to time, enabling each bird to enjoy the added lift.

April 26, 2013

The genetic roots of modern Europeans do not stretch as deep into prehistory as most scientists had thought, reports a joint team of German and Australian scientists. A new analysis of ancient skeletons found in Germany indicates that a major population upheaval occurred in Europe around 4,000 B.C., when long-established populations were suddenly displaced by other farming people moving into the region. These more recent migrants, rather than the older populations, seem to be the direct ancestors of most living Europeans today.

Archaeologists have found fossils and stone tools that show early humans first lived in Europe more than 700,000 years ago. The Cro-Magnon people hunted throughout Europe from about 35,000 years ago to 10,000 years ago. By about 6000 B.C., farming peoples migrated into Europe from the Near East. Most scientists had believed that modern Europeans were descended from these ancient populations. The new findings, however, suggest that most living Europeans are descended from farmers who migrated into the region only about 4,500 years ago.

A megalithic monument near Carnac, France, is one of many of these stone structures made by prehistoric people. The best-known monuments are in western Europe and the Mediterranean region. These sites were built between about 4500 and 1400 B.C., during the Neolithic period and early Bronze Age. The builders made them for religious purposes or as burial places. (© Joe Cornish, Tony Stone Images)

The scientists based their conclusions on an analysis of DNA from 39 ancient skeletons excavated from the Mitelelbe Saale region, near Lepzig. The analysis was published April 23 in the online journal Nature Communications. The team focused their study on mitochondrial DNA (mtDNA)–a form of DNA found outside the chromosomes in cellular structures called mitochondria–that was preserved in the bones. In humans, mtDNA is inherited only from the mother. This makes the material useful to biologists for helping to determine relationships between groups. The scientists chose to examine a particular variety of mtDNA known as haplogroup H, the most common mtDNA variety in Europe, found in about 40 percent of Europeans today. However, haplogroup H is not common in the mtDNA from skeletons of Cro-Magnons or other early European hunter-gatherers, suggesting they made little genetic contribution to modern European populations.

The mtDNA from skeletons dated to the early Neolithic period of Europe, about 7,500 years ago, shows that farmers from the Near East migrated into Europe carrying a version of the haplogroup H with them. However, the international team found that by the Middle Neolithic, around 4,500 years ago, this early version of haplotype H was suddenly replaced by the version seen in modern Europeans.

Scientists are not certain where this newer haplotype H originated. But such a rapid replacement could only result from the migration of new populations into the region. The research shows that the movement of populations in prehistory and the genetic history of modern populations is much more complex than scientists had thought.

Additional World Book articles:

• Agriculture (History)
• Cave dwellers
• Genetics
• Prehistoric people
• Stone Age

March 8, 2013

Beaches on the coast of southern Florida were closed to swimmers this week as thousands of sharks were spotted in the waters near shore. The sharks are migrating north for summer, heading from Florida to North Carolina. This migration  takes them past the shores of many beaches frequented by tourists, including Palm Beach. Scientists estimate that there are approximately 15,000 sharks migrating–mostly blacktips (which grow to be about 5 feet, or 1.5 meters, long) and spinners (which grow to be about 10 feet, or 3 meters, long). The sharks swim about 200 yards (180 meters) out from the beach, but lifeguards closed the beaches for swimming as a safety precaution. Florida had 25 unprovoked shark attacks in 2012, although none were fatal.

The body of a shark. Sharks rarely threaten humans, but authorities will often close down beaches where sharks are sited as a precaution. (World Book illustration by Marion Pahl)

The shark migration is normal and happens every year, but it is usually earlier and does not affect beach season in Florida.  In 2013, the migration is happening during spring break for many schools. Spring break is one of Florida’s heaviest tourist seasons. Scientists are not certain why the migration is happening so late in 2013.

Additional World Book articles:

• Migration

• Shark

Jan. 25, 2012

Snowy owls have been descending on the northern United States this winter by the thousands, to the delight of bird watchers and scientists. These graceful birds of prey usually live on the Arctic tundra in Canada, where they feed mainly on lemmings. Normally, only a relatively small number of the owls migrate south in the winter. The owls have also spread out farther than usual, appearing from the Atlantic coast to the Pacific and as far south as Kansas. One owl even reached Hawaii, where authorities shot it out of concern it would interfere with aircraft. Such a rapid increase in the numbers of a bird in an area where it is not usually found in winter is called an irruption. Scientists have been tracking the locations of the birds with great precision thanks to a citizen science project called eBird. Run by the Cornell University Lab of Ornithology and the National Audubon Society, the online project (at ebird.org) uses sightings collected by bird watchers across North America to create maps showing where species can be found.

Unlike most owls, snowy owls are active during the day, making them easier to observe. The owls reach about 23 inches (58 centimeters) long and have mostly white plumage with brown markings. Adult females have more brown markings than the adult males. The owl’s call features several rough notes and sounds somewhat like a dog’s bark. In addition to lemmings, the owls may feed on mice, voles, ducks, and hares.

Female snowy owls have more brown markings than the males do. Alan D. Carey, Photo Researchers

Scientists are not certain why the owls have migrated south in such numbers. However, many animals in northern regions follow a boom-and-bust population cycle. For example, lemmings quickly grow in numbers when there is abundant vegetation. A boom in the population of lemmings provides abundant food for snowy owls. However, the lemmings soon eat much of the available food, and their numbers plunge. At that point, there may not be enough lemmings to support the large number of snowy owls. These conditions may cause snowy owls to fly farther south than usual, as they seek other sources of food. The irruption is expected to end by March or April.

Additional World Book articles:

• Audubon, John James
• Bird
• Spotted owl