Nature Smart

Bird migration is still one of nature’s most interesting-yet-mysterious events. On the surface, migration seems rather simple and straightforward, but if you stop and take a detailed look, you will see it offers every shade of complexity possible. 

There are over 11,000 species of birds, and about 40% partake in some form of migration. Migrations range from simple elevational changes for species that live in the mountains, to short-distance movements to avoid unfavorable weather, to long-distance trips to warm climates to escape winter, to the granddaddy of them all—migration from one end of the Earth to the other. Right away, you can see there is more to migration than perhaps you thought.

In the 1800s, we didn’t understand much about migration. We thought it was impossible for a tiny bird to navigate over great distances and endure huge physical demands, so we said it was impossible and we came up with our own ideas to explain the unexplainable. It was thought that hummingbirds had to migrate on the backs of geese, in order for them to escape winter. We also said that some birds dove down to the bottom of ponds and overwintered in the mud. These kinds of theories now seem preposterous and outlandish. Yet at the time, they were accepted as fact.

In the 1900s, we started to develop new ways to study birds. Some of the earliest attempts to track migration involved catching a bird and tying a brightly colored ribbon on its wing, in hopes of being able to find the bird again during winter. This wasn’t very efficient, and one had to have an idea of where the bird stayed for the winter already to make this work.

When transistors were invented in the 1940s, the breakthrough made small electronics possible. By the end of the 1900s, small devices were used to track the migration of free-flying birds. This was the beginning of our better understanding of bird migration, but it was just the tip of the migration iceberg.

In just the past few decades, so much new—and almost unbelievable—information about bird migration has completely turned our understanding of migration upside down. Today, there are many ways to track migrating birds. One of these migration tracking tools is a website called Bird Cast from Cornell Lab. It can be found at www.birdcast.org. All you need to do is put in your county and state; then, each day during the migration season, you can see how many birds passed over your county on the previous night.

There is a ton of information available to anyone who is curious about what is going on with migration. In addition to the tally of birds migrating through your county, there is also information about what time they migrated, the timing of each nightly flight, along with flight direction and altitude. The site also has a list of the expected species that should be migrating.

For example, as I write this, 97,400 birds passed over my county last night, and at one given moment last night, 36,400 birds were in flight, traveling SSW at 14 mph, at an altitude of 600 feet, all at one time. In order to gather all this data, Bird Cast uses data from the national network of weather surveillance radars (NEXRAD). Sophisticated algorithms and machine-learning models are applied to the radar data to separate weather, such as precipitation, from biological signals (the birds). It then analyzes the strength of the radar signals to estimate the number of birds that are flying. Just like with weather, the data is used to give migration forecasts to predict nocturnal bird migration for the next few nights.

We sure have come a long way in our understanding of bird migration, unlocking some of the most mysterious natural events of nature. However, no doubt, there is so much more we don’t understand about bird migration, and we will surely learn more in the years to come. Until next time…

Stan Tekiela is an author / naturalist and wildlife photographer who travels extensively to study and capture images of wildlife. He can be followed on www.instagram.com and www.facebook.com. He can be contacted via his website www.naturesmart.com.