Very possibly the most intriguing aspect of animal biology is migration. Birds migrate. Mammals migrate. Reptiles migrate. Insects migrate. Fish migrate. Crabs migrate. I could go on and on.

The distances traveled can be relatively small; for example, robins only migrate a few hundred miles, and the North American blue grouse only migrates a few hundred meters. Then you have the true champions of migration. The Arctic tern flies from its breeding grounds in the Arctic to the Antarctic and then back again. It may spend up to four months of the year in migration, traveling over 44,000 miles.

On the ground, it is the caribou that has the longest migration route, covering about 2,000 miles a year. The most widely known land migration is on the Serengeti. This is a large savanna in Tanzania and Kenya in which millions of wildebeest, zebras, and gazelles travel a circular route of about 1,250 miles. Here in the U.S., you can go a ways south and observe the migration of tarantulas, which will travel over 20 miles to try and find a mate. Yep, spiders migrate.

When we were in Cuba a few years ago, we got to witness the Cuban crab migration. Literally millions of crabs make their way from the hills and forests of the island to the sea to lay their eggs and then back again. These aren’t small crabs. Their body is more than six inches across, and the males have a claw that is another six inches long.

When it comes to birds, there have been hundreds of studies that have tried to determine the “why” and the “how” of migration. We know that some birds learn their migratory route; cranes and geese, for example. Others, like the ruby-throated hummingbird, head south the first year with no instruction. Yet, they make it to the southern wintering grounds instinctively, flying nonstop for 24 hours in order to cross the Gulf of Mexico.

How? We know that birds do use known landmarks from previous migrations, and they also use the location of the rising and setting sun to get their bearings. Most songbirds migrate at night, and they use the stars. Also, birds have special proteins in their eyes that are sensitive to the Earth’s magnetic field…a built-in compass.

We know that the number of hours of daylight, temperature, and food availability trigger migration, and there is even a word that describes the restlessness that birds exhibit just prior to migration. It is the German word, zugunruhe, meaning migratory restlessness.

So what got me thinking of migration? The numbers are in for the fall bird migration over Nebraska and Dawson County. The numbers were down a little for the County. This year, from Aug. 1 through Nov. 15, an estimated 55,752,000 birds flew across Dawson County. For the State, the estimated number was 549,543,800 birds, the highest number ever recorded for Nebraska.

Generally the states with the highest number of migrants are Florida, Georgia, and those along the southern Mississippi River. However, this year, Texas won the migration number award with an estimated 1,073,956,700 birds migrating across the State and heading out across the Gulf to their wintering grounds in Central and South America.