Fall Migration is for the Birds

I heard them before I saw them, of course. Their distinctive honk-honk-honk alerts me that fall is here, and winter is not far behind. Snow geese (Anser caerulescens) are on their way to winter in the southern US. Others fly as far as Central Mexico. Birds are in the midst of the great bird fall migration. When I say birds, I mean some 4.7 billion of them according to The Cornell Lab of Ornithology.

Why do birds migrate?

Simply put, there are two main reasons: food and cold. As winter approaches the supply of seeds, nuts, grains, and insects decreases. That, as well as shorter days and cooler temperatures, alert the birds to move on to better climes. Genetic predisposition pushes many with a strong urge to head south. Birds that deliver offspring later in the season will not leave until the fledglings are mature.

When can you see birds migrating?

Birds are either diurnal or nocturnal migrants. Those that you typically see during the day, diurnal migrants, will fly during daylight. That includes many strong fliers like raptors, pelicans, and even hummingbirds.

Birds that travel at night, nocturnal migrants, are generally those that you rarely see during the day. That includes those that prefer thick vegetation or wooded areas, rarely leaving those habitats. Flying at night gives birds like thrushes, warblers, and orioles protection from predators. They feed and rest during the day to prepare for another long night of travel.

How far do birds migrate?

Well, that depends on the birds. Migrants range from short to medium to long distance travelers. Short-distance migrants may move from a higher elevation to a lower. Medium-distance migrants may leave the Northern states and head to Florida or Texas.

It is the long-distance migrants that astonish us. The whooping crane will easily leave Wood Buffalo NP in Alberta and arrive 50 days later at Aransas NWR in Texas. That is a bit over 2,500 miles through the Central Flyway. ( Flyways map)

Not to be outdone, the Rufous hummingbirds depart from Alaska and head to central America via the Pacific Flyway traveling some 4,000 miles in just a few weeks. 

Ruby-throated hummingbirds leave their Northern US habitats for Mexico traveling over 2,000 miles. That includes a 22-hour non-stop flight over 600 miles of the Gulf of Mexico.

So, leave those feeders up until at least 3 weeks after you see the last hummer. Those that get a late start will need that food stop for energy. Hummers weigh about the amount of a Lincoln-head penny. It doubles its weight for the long flight.

How do birds know where to go?

Scientists have no definitive answers, but research points to several ways. Birds navigational skills are exceptional as they are able to get direction from the location of the sun, the stars, and even the earth’s magnetic field. Many follow known landscapes that offer food, water, and protection. Even young birds on their first migration seem to sense where to go.

How can you find out which birds are migrating in your area?

The Cornell Lab of Ornithology, Colorado State University, and University of Massachusetts-Amherst have banded together to create Birdcast. This application released in 2018 uses Doppler weather radar data to track when, where, and how far birds migrate in real time. The dashboard lets you enter your county and state to see the latest information about bird migration in your region. I believe that you will be totally amazed at what you find.

Additional Information:

• All About Birds
• BirdFact
• The Backyard Naturalist

Photo Credits:

• Snow Geese, Port Louisa NWR, Wapello, Iowa, Public Domain
• Whooping Cranes, Jim Hudgins/USFWS, Public Domain
• Rufous Hummingbird, NPS/Andy Bridges, Public Domain
• Ruby-throated Hummingbird, abbeyprivate, Public Domain