Finding Their Way
Think about this: would you be able to find your way out of unfamiliar woods? Obviously, animals don’t have maps or a GPS (Global Positioning System) device to aid them. According to NASA, instead of ancient star maps, we use satellites. Over 30 navigation satellites are zipping around high above the Earth. These satellites can tell the GPS exactly where we are. Animals don’t use those either. Instead, animals that migrate use their senses and memories to find their routes. We’ve learned that turtles and other species use the earth’s magnetic field as a guide. Other animals follow earth’s landmarks such as, mountains, rivers and coastlines. Oceanic creatures often use echolocations, bio sonar, and waves to travel by; and birds use the sun, moon and stars as well. Bats—more than half of the 900 species of bats—rely on echolocation, ultrasonic clicks, to detect obstacles in flight, find their way into roosts, and navigate different locales to forage for food.
Scientists often study animal migrations in order to help different animal species, and to realize some of the stressors they endure with this instinctual activity. Their arsenal of tracking tools involves a variety of techniques such as: tracking animals from airplanes and using land and water vehicles. Others use satellite cameras or by attaching radios or transmitters to animals. Birds are often banded, butterflies tagged and that system depends on other people spotting the bands and taking the information to put into a universal database or mapping program. According to Fish Life, “Each year, ASF (Atlantic Salmon Federation) researchers surgically attach pop-off tags to selected salmon allowing them to track their movement from the river to feeding grounds in the ocean. The tags measure light, depth and temperature to calculate a daily position for the fish. They store the data until a predetermined date when they pop off and begin transmission. …The tags were found on beaches in Greenland and Ireland, thousands of kilometers from where they were first released.”
All animals in some way, prepare for their trip. Pronghorns (Antilocapra americana a type of American antelope) graze in Wyoming’s Grand Teton National Park all summer before walking 150 miles south. Some animals gain weight; others take extra fat into their diet. Monarch butterflies add fat by sipping nectar. And when they arrive—after leaving the northern U.S and Canada for southwest Mexico—they rest closely together in a semi-dormant state, often on the very same oyamel, or sacred fir trees their ancestors occupied the year before. Birds molt worn-out older feathers and grow newer, strong flexible keratin ones before heading out (in addition to flying in precision-like order to take advantage of air drifts!) The birds’ formation fits the theoretical predictions of aerodynamics to conserve energy. Ecophysiologist Steven Portugal, at the Royal Veterinary College in Hatfield, UK., says, “They’re placing themselves in the best place and flapping at the best time,” he says. (You may hear Canadian geese loudly honking to each other, a kind of buddy system, that is helping them to keep track of each other without looking around.) A species like Whooper swans (Cygnus cygnus ), similar to Trumpeter swans, can leave Siberia and winter in small numbers in the Aleutian Islands, Alaska; they can fly more than 800 miles (1,300 km) without resting. Likewise, Ruby-throated hummingbirds head to Central America and fly nonstop for more than 30 hours across the Gulf of Mexico. Manatees migrate as water temperatures change; if water is too cold, they can die. They often follow the same routes that their parents did, chewing on vegetation along the way. River Ventures, a manatee tour center, says that the Crystal River is one of the only rivers in Florida where people can legally interact and swim with the manatees in their natural habitat and tells us that, “Because the water temperature in the springs of Kings Bay, the headwaters of Crystal River remains a constant 72 degree temperature, over 400 manatees will migrate to Crystal River each winter to seek refuge from the cold Gulf waters.
The Arctic tern (Gavia arctica) is probably the world’s champion migrator. It wants to live in constant sunshine and because of this, it travels over 20,000 miles every year. In June and July is enjoys plenty of sun, and in December and January, it enjoys the constancy of sunshine in the Antarctic summer. And what about climate change? The Common Loon, according to Audubon’s climate model, by 2080, will “lose 56 percent of its current summer range and 75 percent of its current winter range… In both seasons the potential to shift northwards in a warming climate is significant… Minnesota will lose its iconic loons in summer by the end of the century.” Reference Beehler, Bruce M. North on the Wing: Travels with the Songbird Migration of Spring. Washington, D.C.: Smithsonian Books, 2018. Book. Heinrich, Bernd. The Homing Instinct: Meaning & Mystery in Animal Migration. Boston: Houghton Mifflin Harcourt, 2014. Book Markle, Sandra. Snowy Owl Invasion! Tracking an Unusual Migration. Minneapolis: Millbrook Press, 2018. Mebane, Jeanie. Animal Migration. Burlington, VT: Capstone Press, 2013. Book. Audubon; the Common Loon Beauty of Birds: Whopper swans River ventures: Manatees NASA: How does Global Positioning Work?
National Geographic: “Monarch Butterflies Migrate 3,000 Miles—Here’s How”
Nature: “Precision formation flight astounds scientists Flocks accomplish a feat of coordination to save energy during migration.”
Project Snowstorm Winter 2017-18 Scientific American: “How do bats echolocate and how are they adapted to this activity?” The Cornell Lab of Ornithology The Fish Site: “Returned Atlantic Salmon Tracking Tags Aid Fish Research” Photo courtesy of Pixabay.com