Northern elephant seals come to shore twice a year, once to reproduce and once to shed old fur and skin during the molt. Baird via Wikicommons under CC BY 2.0Ī familiar sight along the California and Baja coasts, these sedentary-looking mammals actually cover a lot of ground. Northern Elephant SealsĮlephant seals in San Simeon, California, in January 2009. Track the monarch migration with this interactive sighting map from the University of Wisconsin-Madison Arboretum. We have really good evidence that the smallest individuals just don’t make it, so the migration is promoting large size with monarchs in North America.” Survival of the fittest is appropriate, but in the case of the monarch it’s really survival of the biggest.
“A lot of research shows how important this selective migration is in literally shaping the features of the monarch. The journey is so arduous that it actually makes the population physically distinct from non-migrating monarch groups, says Davis, who specializes in monarch butterflies. In the fall, a single long-lived generation of monarchs retraces the entire southward route. When venturing north, the monarchs stop to lay eggs, which as larvae fatten up on milkweed before becoming butterflies and resuming a journey that requires four or five generations to complete. Spring finds a subspecies of these butterflies on a 1,900-mile northward journey from the mountain forests of central Mexico, where they winter by the millions, to countless backyards in the U.S. Monarch butterfly, ( Danaus plexippus) feeding from a flower in Bunbury, Western Australia. But if you’re not going to stop on the way, then you’d better take it with you.” Monarch Butterflies “It’s pretty crazy to think that you’re adding 50 percent of your body weight and then going on this marathon journey. How do these godwits pull it off? “They have to put on so much fat that they become like butterballs at the stopovers,” Davis says. The layover in Asia is the birds’ only respite before finishing the flight with a 3,700-mile leg to their summer breeding grounds in the Yukon and Alaska. In spring in the Northern Hemisphere the birds leave New Zealand for an eight- to nine-day journey to the food-rich mudflats of the Yellow Sea off the coasts of China and Korea. The migration is the longest nonstop flight of any known bird-an incredible 7,000 miles. “They will try to do the entire journey in one leg without stopping,” Davis says. Though their migration is a long one, layovers aren’t part of the bar-tailed godwit’s flight plan. Bar-Tailed GodwitĬC BY-SA 2.5 Andreas Trepte, via Wikicommons under CC BY-SA 2.5
En route they may eat lichen, which a special strain of gut bacteria allows them to digest, but by the time they reach Hudson Bay in June, plants and grasses are plentiful. That’s a distance of about 400 miles as the crow flies, but satellite tracking shows that the animals might actually zig and zag over 3,000 miles a year to complete the round trip.Įastern migratory caribou herds (which have declined alarmingly in recent years) winter in Ontario and Quebec’s boreal forests but head for the tundra each spring. The Porcupine Herd, some 170,000 animals strong, winters south of Alaska’s Brooks Range and in the Yukon but migrates north to the Arctic Coastal Plain for calving. CaribouĪ herd of caribou or reindeer on the coast of the Chukchi Peninsula in Russia.įamed for circumnavigating the globe on December 25, many reindeer (also known as caribou in North America) spend the rest of the year on an equally epic circuit, hoofing it to greener pastures.Īlaska is home to more than half a million caribou in seven migrating herds. If you are in the right spot on the planet, you might even catch some of the natural world’s most incredible migrators on the move. So every year it’s a selective episode that helps to keep the population strong.” “It allows them to exploit different resources that they wouldn’t have been able to find if they’d stayed put, but a lot of animals die trying to complete migrations. “It’s hard it’s a taxing, energetically expensive journey,” Davis says. These journeys are about as diverse as the species themselves, but Andy Davis, a University of Georgia ecologist and editor of the journal Animal Migration, says the mass wildlife movements have one important thing in common. Vernal migrations feature everything from fish and birds to big, shaggy mammals and tiny insects. Spring is in the air, and the animal kingdom is on the move.
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