|Many animals, from bees to humpback whales, can
find their way accurately from one place to another. The methods they use
to navigate vary from simple to extremely sophisticated. Animals navigate
in a variety of ways. Many bird species find their way using the earths magnetic
field as a guide, while eels and salmon rely on chemical changes in the water.
Still other animals like bats and whales navigate with the use of sound waves
that allow them to avoid obstacles.
Visual Cues: Many animals find their way simply by using landmarks to identify their surroundings. Migrating birds spot familiar features along rivers and coastlines to keep them on their route. Mammals and insects navigate over short distances using features in the landscape for reference. Other animals use the position of the sun in the sky as a guide, but this is more difficult because the sun moves during the day. Birds, bees, solitary wasps, ants, and some butterflies make allowances for the movements of the sun to judge their position.
Even in cloudy weather these animals are able to continue their journey by using polarized light. The light from the sun shines in all directions, but as it passes through the atmosphere it becomes directed, or polarized. Bees, frogs, and toads are also able to orient themselves by using the stars, much the way we use the North Star to identify north.
Chemicals: Salmon migrate from their birthplace in freshwater rivers to the ocean and back again several years later. Vision plays a part in their finding the coastline. The fish also probably detect chemicals in the water and recognize their own river. Chemicals also play a part in the migration of the European eel to its breeding grounds across the Atlantic. Green turtles move every year from Brazil to breeding beaches an Ascension Island in the South Atlantic. They return each time to the same place. Scientists think smell helps them recognize these sites. Some female moths release a chemical scent, known as a pheromone, which attracts males, often from great distances. The male Chinese saturnid moth can find a female seven miles away
The Earths Magnetic Field: Invisible lines of force exist between the magnetic north and south poles of the earth. A compass can detect them. Humans can navigate using a compass; some animals, too, may use these magnetic lines to navigate. Whales may follow these lines, which could explain why they get stranded in inland waterways. Birds use the earths magnetic field to navigate. On cloudy nights, when birds cannot see stars and landmarks and there is no light to guide them, some can still orient themselves correctly.
Emperor penguin pairs separate and migrate over long distances in a snow covered landscape with no recognizable features, but they still meet up at the same point. But if the magnetic field is upset, birds become confused. Scientists have studied the homing pigeon, which can fly home accurately from great distances. Albatrosses are able to home over even greater distances. In order to use the magnetic field for navigation iron must be present in the bodies of homing animals. Magnetite, a form of iron, has been found in pigeons’ brains, as well as in bees.
Sound: A bat makes high pitched sounds that hit objects in its path and bounce back to its ears. This process, called echolocation, is very accurate, enabling the bat to find its way in dark caves, avoiding obstacles and catching flying insects, such as moths. The moth may emit “jamming” sounds to confuse the bat. Some birds also use echolocation to find their way in caves. Whales and dolphins use sound to communicate with each other, to find a mate, and to keep groups together. The giant blue whale calls to other whales hundreds of miles away. The male humpback whale makes long, complex, song like calls that travel across the oceans. A beached whales call may sometimes guide its companions to a similar fate.
Honey Bees: When worker bees find a source of nectar, they return to the hive using the sun to navigate. When they return they communicate with the other bees, telling them the distance to the food source and its direction in relation to the sun. They alter the information during the day to allow for the suns movement. The “round dance” tells other bees that there is food within 250 feet of the hive. The other bees must track the dancers scent to locate it. In the “waggle dance” the dancer flies in two overlapping semicircles. The bee waggles indicates distance. The angle between this part of the run and the vertical equals the angle between the sun and the food source. The bees must fly out of the hive at this angle.
Fast Counter by bCentral
All material copyright ©1996-2018
Ladywildlife©..& mcmxci imp b/imp
inc. wildlife fact files tm