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)

July 17, 2014

Changyuraptor yangi may have preened like a peacock, and considering its amazingly long tail and wing feathers, who could have blamed it? The dinosaur’s 12-inch (30-centimeter) tail feathers are the longest ever found on a dinosaur, according to the scientists who published a description of C. yangi‘s fossil this week. Long feathers also covered the animal’s winglike arms. Its hind limbs were so heavily feathered that they looked—and may have acted like—like a second set of wings. Although C. yangi was only about 4 feet (12 centimeters) long, it is also the largest of a number of the four-winged dinosaurs discovered in fossil-rich Liaoning province in northeastern China. Paleontologist Luis Chiappe of the Natural History Museum of Los Angeles led the team that found the fossil, which dates to about 125 million years ago during the Cretaceous Period.

C. yangi was a microraptorines, a group of predatory, feathered dinosaurs related to raptors, including Velociraptor. The microraptorines were close cousins of birds, with whom they probably shared a common ancestor. C. yangi was about 60 percent longer than the largest microraptorine found previously and weighed about 9 pounds (4 kilograms). It had razor-like teeth and claws and probably hunted fish, small mammals, and birds.

Microraptor, shown in this illustration, was a small, birdlike dinosaur with feathers on its arms and legs. World Book Illustration.

The dinosaur’s tail feathers are the “crown jewel of the specimen,” Chiappe said. They were some 5 inches (13 centimeters) longer than any found before. Chiappe believes the long tail feathers helped to slow C. yangi in flight and avoid crashing when coming in for a landing. He also argues that the long tail feathers suggest that the dinosaur could actually fly, taking off by flapping, and not just glide.

Additional World Book articles:

• Microraptor
• Paleontology (2012) (a Back in Time article)

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.