Explainer: Nine epic treks of the animal world

  • Image: Salmon shark
    Barbara Block  /  Stanford University file

    Some animals will travel the Earth for a good meal, others for a hot mating date or to escape the cold. The sooty shearwater, for example, logs 40,000 miles a year in its figure-8-shaped route over the Pacific Ocean in pursuit of fish, krill, and squid. Humpback whales routinely swim between the tropics and poles to keep their pods and bellies full. To learn more about these epic journeys, scientists outfit some critters with electronic tracking tags, chase — and at times, lead — others in ultralight airplanes, or record who went where by identifying tell tale bodily markings when the animals appear in different parts of the globe.

    In this image, scientists prepare to outfit a salmon shark in Alaska with a satellite tracking tag. The tags revealed that some of the ocean predators routinely swim between the glacial waters of Alaska and the warm seas in Hawaii. One shark swam a total of 11,321 miles in a 640-day period. Click on the "Next" label to learn about eight other epic journeys.

    — John Roach, msnbc.com contributor

  • Fantastic flutter

    Marco Ugarte  /  AP

    Bright orange and black monarch butterflies may look delicate, but some are capable of fluttering thousands of miles from summer feeding grounds to winter retreats. The longest treks exceed 3,400 miles between southern Canada and a few select forested mountains in Mexico. But not every monarch is up for the journey. Only the fourth or fifth generation of the summer suspends reproduction and heads south. And it only comes partway home, laying eggs at a way station. It takes two more generations before the grandchildren reach the summer grounds. How the butterflies accomplish this feat is a subject of continuing research.

  • Whale tale

    Image: Humpback whale
    Itsuo Inouye  /  AP file

    Telltale markings on the tails of humpback whales allow scientists to track the leviathans' treks between a good meal and a place to mate. The 40- to 50-foot-long, nearly 80,000-pound sea mammals spend the summer months in the polar regions gorging on shrimplike critters, plankton and small fish and then head for the tropics where they fast, mate and give birth. Humpbacks are found throughout the world's oceans, but the record-holding migrants belong to a population that winters off the Pacific coast of Central America and summers in the Antarctic. Some swim more than 5,100 miles each way.

  • Empty nesters

    IMAGE: ALBATROSS AND CHICK
    Ryan Hagerty  /  U.S. Fish and Wildlife Service via AP

    For some albatrosses, a trip around the world filled with fishy meals appears to be the best cure for empty nest syndrome. In a study, researchers placed tags on the sea birds that recorded their location twice a day for 18 months. The recovered data showed that more than half the albatrosses circled the globe at least once. One bird circled the globe three times. Another made a single 13,000 mile loop in just 46 days. The findings, researchers hope, will help protect the birds from fishing fleets.

  • Wandering turtles

    Image: Leatherback Turtle
    Getty Images  /  Getty Images file

    Leatherback sea turtles teeter on the brink of extinction in part because their ocean wanderings all too often end with deadly entanglement in fishing gear. But the intrepid turtles, which can grow up to 9 feet long and weigh more than 2,000 pounds, ply the world's oceans far and wide. Males spend their lives at sea and females come ashore only to nest and lay eggs. One female turtle recently fitted with a satellite tracking tag swam from Indonesia across the Pacific Ocean to Oregon and back to Hawaii — a distance of 12,744 miles over 647 days.

  • A figure-"ate" course

    Image: Sooty shearwaters migration
    Proceedings of the National Acad

    Small seabirds called sooty shearwaters go to big lengths for a good meal. The birds, which have a three and a half foot long wingspan, travel about 40,000 miles every year, according to tags that tracked their movements electronically. The birds trace a giant figure-8 circuit over the Pacific Ocean using prevailing winds to chase easy feasts of fish, squid, and shrimplike krill. The journey takes them north to the Bering Sea, south to Antarctica, east to Chile, and west to Japan and New Zealand. The research may help scientists understand why the birds' numbers are declining.

  • Whooping crane odyssey

    Matt Mendenhall  /  AP

    Each fall, about 20 whooping crane chicks follow ultralight airplanes and pilots clad in whooping crane costumes on a 1,250-mile journey between their summer nesting grounds in Wisconsin and a winter retreat on the Florida coast. The spectacle is part of an effort to reintroduce the endangered migratory birds to their former range. The entire flock makes the return journey unguided in the spring. The world's only natural, wild migratory flock shuttles about 2,600 miles each spring and fall between northern Canada and the Texas Gulf Coast.

  • Great shark swim

    NICOLE
    AP

    A female great white shark boggled scientific minds when she swam from South Africa to Australia and back again in just under nine months. The journey logged more than 12,400 miles. The finding stemmed from a long-term tagging project to learn more about the life history of great white sharks, including their migratory patterns. The transoceanic treks may be rather common, a finding that suggests distant shark populations are more directly related than previously thought.

  • King salmon run

    Image: Chinook salmon
    U.S. Fish & Wildlife Service

    Chinook salmon don't forget from where they came. They spend the last months of their lives returning to their natal streams to spawn and die. In Alaska, where the fish are called kings, some journey more than 2,000 miles up the Yukon River to extreme headwaters across the border with Canada. The trip may last 60 days. In other regions of the Pacific, Chinook make shorter swims but for a host of reasons the numbers making the journey are perilously low.

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