Birds on the Brain

Fall Migration Brings Diversity of Birds

As the seasons change, bare trees and fields of brown flower seedheads stand sentinel in the early dusk.

It’s a world ready for winter.

Ready, too, are billions of chattering, honking, calling and chirping birds that migrated south.

Between July and November, waterfowl and songbirds traveled regular migration corridors, flying from as far north as Alaska and Canada to overwinter in warm spots as distant as the Caribbean or South America.

And their flight paths took many birds right over the Tennessee Valley region.

“Birds take paths of least resistance, whether along the top of the Appalachian Mountains or coming down the Mississippi Flyway,” Joshua Argo, Tennessee Valley Authority terrestrial zoologist, said.

And some bird species – such as waterfowl and grassland songbirds – chose to overwinter here.

That’s good news for birders living in TVA’s seven-state service area.

“TVA provides habitat diversity,” Damien Simbeck, TVA senior program manager of Natural Resources west operations, said. “If you can have wetland areas, scrub, mature forest and tall grass fields – all that in the same vicinity – you're going to increase the number of species, because something's going to be available for each group.”

And TVA offers up all of those habitats – reservoirs, rivers, forests and fields, as well as in the cropland TVA’s partners manage for waterfowl.

That means this winter, there’s a spot for everyone to enjoy birds.

Bird Brain

If someone says, "bird brain," it should be a compliment.

From the smallest warbler to the largest crane, birds know how to follow the same migratory paths year after year.

Flying solo or in flocks, they navigate at night all the way across the country – even the continent – in different types of weather over hills, forests and fields that can change year to year.

“Some fly across the Gulf of Mexico to get to Central and South America,” Simbeck said. “They go from the Alabama and Louisiana coast to the Yucatan Peninsula in a single flight. Others actually go around the Gulf through Texas and Mexico, and then others just go through Florida and spend the winter in the Caribbean.”

And they’re very efficient about it.

“Birds fly south enough to survive, but make the flight as short as possible,” Simbeck said.

For many birds, the final winter destination is here in the Southeast.

People can spot them near rivers and reservoirs and in the transition zones between forests and fields.

Winter waterfowl residents include lesser and greater scaup, ring-necked ducks, sandhill cranes and white pelicans.

Reservoirs offer special shoreline habitat because TVA’s river managers draw down water levels each fall. That exposes wide strips of mudflats where large birds such as migratory sandhill cranes can spend the night, foraging for crunchy crustaceans and aquatic insects.

Surrounding flooded fields – managed by the U.S. Fish and Wildlife Service or state wildlife agencies – offer cozy cover and nutritious grain.

“We have a population of white pelicans that overwinters on Watts Bar Reservoir from the Great Lakes region,” Argo said.

Wheeler and Kentucky reservoirs have large white pelican populations, too, Simbeck said, and it’s for a unique reason.

“In historical times, they migrated from the upper Great Plains, Manitoba and Alberta (Canada) south to coastal Texas and Louisiana,” he said. “They got wiped out by DDT (in the mid-1900s) and their numbers plummeted. (By the time) DDT was banned and their numbers started coming up, TVA had built reservoirs in the southeastern U.S.”

And pelicans used their bird brains to adapt.

“The new populations said, ‘OK, why go to Texas if I can go to Kentucky and Tennessee and Alabama?’” Simbeck said. “‘It’s a shorter flight and there's plenty of food. I fly as short a distance as I can to survive.’”

Rest Area Ahead

During spring migration, birds fly directly north to breeding grounds.

But in fall, birds take their time on their journeys south.

“You can see a lot of birds during fall migration, because they are feeding on ground level, not just flying overhead trying to get where they're going,” Simbeck said. “They fly at night, land to feed during the day, try to build up fat stores.”

Different species follow different paths.

“For shore birds, it’s shorelines,” Argo said. “If you have birds that focus more on marsh habitat, they're going to stay in riparian areas along rivers, inlets and oxbow lakes. You'll probably find them more toward the Mississippi and TVA’s western region as opposed to the mountains. It just depends on what their habitat requirements and their dietary needs are.”

Waterfowl seek very different food from what passerines – songbirds – eat.

“The woodland birds are looking for areas with lots of insects and lots of seeds – things with high oil content to build up those fat stores,” Simbeck said. “Trees that have lots of insect predators on them, like hackberries that have a lot of caterpillars feeding on the leaves, attract a lot of migrants.”

Landscapes that humans might see as scrubby, such as the edges of forests and roads, are irresistible to birds, too.

“Actually, one of the best fall foods available is poison ivy,” Simbeck said. “It has a great benefit when it comes to fall migration. Its berries are a big food source for thrushes, rose-breasted grosbeaks, orioles, things of that sort.”

While scrubby edge areas are in decline across the country, they’re abundant on TVA’s transmission line rights of way.

“Rights of way are very good areas for fall migration, especially the ones with the power lines running north-south,” Simbeck said. “Birds will follow the power lines like they would the Appalachian Mountains … because they know the food source is there.”

Grasslands – fields of native plants – also offer great habitat for migratory songbirds and their hawk, eagles and owl predators that hunt rodents, too.

“Our Natural Resources group manages a lot of grasslands through prescribed burns,” Simbeck said. “We're constantly trying to increase the percentage of native warm-season grass on TVA properties, either as big fields or in lands we lease for agriculture.”

In TVA-restored grasslands such as those around Normandy Dam, birders can spot flitting seed- and insect-eaters such as dickcissels and grasshopper sparrows, Simbeck explained.

Bird Bonanza

As temperatures plummet, birding offers a way to stay active. Throughout the Valley region, Simbeck and Argo urge people to notice birds flying overhead, sheltering in a tree or feeding in the fields.

Noticing is the first step to becoming a bona fide birder. You can link song to bird using apps such as Cornell Ornithology Lab’s Merlin Bird ID, and a quality birding book can open a world of discovery.

“That's the best way for you to learn,” Argo said. “Always learn new songs, new birds, try to expand your life list.”

“And it is very addictive,” Simbeck laughed.

“It is,” Argo agreed. “You’ve got to see them all, got to hear them all."