Backyard Nature: The fall migration has started

by Marjorie Rachlin

At night, high above us, a stream of birds is flying. Migrating birds are on the move. Some of them are migrating short distances – 200 to 300 miles – but many are long-distance migrants going to the tropics. Go out after dark, and you may hear their flight chirps.

Migration is a worldwide phenomenon in the northern hemisphere. South in the fall, north in the spring. September is the peak month for songbirds in our area.

Migrating birds’ flights over and stops in our area are on a path called the Atlantic Coast flyway, which runs from Canada and the New England states south along the sea coast. (There are three other U.S. flyways – the Mississippi, the Rockies and the Pacific Coast.)

The Cornell Ornithology Lab has an animated map here that shows the birds moving south, and then reverses the show for the spring. The lab’s experts meticulously charted the paths and stops of 118 species of U.S. birds, and the moving map is a fascinating visual of migration.

Our location gives us good birding for passerines (songbirds) – tanagers, orioles, thrushes, vireos, flycatchers and the pièce de résistance: warblers. Hawks need the thermals of the Appalachian ridges, and shorebirds like the coast. The article will deal with the songbirds because we are most likely to see them.

Where are they going?

Most of the birds on our flyway are heading for Mexico, Central America or northern South America (Columbia, Ecuador, Peru), although often some of the species will winter in Florida and states along the Gulf.

Baltimore orioles are one of the species that make the long trip. In July they begin to eat more to build up their energy reserves. They molt, and they grow a new set of feathers. Then, sometime in September, little local flocks begin to gather. They will take off on different days over a period of a month or so.

An oriole flock usually flies 100 to 200 miles a day, weather permitting. When they reach the southern states, some will stay there for the winter, but others will continue to the tip of Florida to get prepared for the rest of the journey. They will fly non-stop, 400 to 500 miles, over the Caribbean Sea to Central and South America. If the weather is bad – storms, high winds, hurricane – many will die on the way.

Hummingbirds, some thrushes and many warblers also take this difficult route.

Why are they migrating?

Most of the migrant birds are insect eaters. When cold kills their food supply, they leave. In the spring they return because they need an abundant insect supply (protein) to feed the babies, and the insect population is greater in temperate zones. Many experts think that this pattern developed originally when glaciers covered Canada and the northern states.

Rock Creek Park is a hotspot

The local hotspot for DC birders is the ridge at Rock Creek Park (along Glover Road, south of the Nature Center). Serious birders will arrive on the ridge at 6:30 or 7 a.m., when the birds usually drop down after flying all night.

Shortly after dawn the migrants begin to look for a green spot to eat and rest. They see Rock Creek Park below, and some of them even remember it from past trips.

When they first come down they are hungry. They dart around, looking for insects and berries, in a kind of perpetual motion. Finding a moving bird in your binoculars and identifying it (“ID-ing” in birder parlance) takes skill. “Is it an immature blackpoll or an immature bay-breasted?” That is the challenge for a dedicated birder.

Surprisingly, after 9:30 a.m. the birds disperse and seem to disappear, spending the day resting and feeding. Shortly after sunset they take wing again.

On a good day with a north tailwind at night, the birders as a group might tally a list of 50 or more species of birds. The group in the photo above found ten different species of warblers in Rock Creek on August 24th, a good number for that date.

Backyard birds

Many of our nesting birds are year-round residents – cardinals, mourning doves, chickadees, blue jays and others. Winter doesn’t scare them. They are looking forward to our feeders.

Carolina wrens (photo above) stay home but you won’t see them often at the feeders. They want suet, not seeds. Robins too may stay, although quite a few robins leave in October. If it is a warm winter you will see flocks eating the berries from your holly trees all winter. When they sense a real cold spell, they become short distance migrants and move several hundred miles south.

Hummingbird feeders should stay up through October. After local hummingbirds go, there is often an influx of migrants from further north, who need feeder energy to stoke up.

Join the local birding gang to witness the migration

Rock Creek Park is a great place to start. The group is friendly, and you will need their help to find and identify birds. Put on boots and high socks, long pants, a long-sleeved shirt and a hat. Tuck your pants into your socks. Binoculars are a must.

It’s best to get up on the ridge around 7 or 7:30 a.m. A good place to start is the Maintenance Yard parking lot just south of the Nature Center. To get there, take Glover Road, which runs south from Military at the light near St. John’s school.

Drive past the turnoff for the Nature Center and shortly you will see the sign for the Maintenance Yard. Park in the lot and wait for a birder to come along and show you how to get to “the Yard.” Many birders start their day here.

This is a bad year for ticks, so cover up and check yourself carefully (including hair) when you get home.

Resources

Both local Audubon groups have scheduled field trips. The DC Audubon society lists events at audubondc.org/fieldtrips. Visit anshome.org for the Audubon Naturalist Society headquartered in Maryland. The Northern Virginia Bird Club lists its field trips at nvabc.org.

My sources for this article came from Wikipedia and a wide search on the Internet, as well as my own experience as a Rock Creek birder. There is all sorts of help on identifying birds on the Internet. I am old-fashioned and use a book – The Sibley Field Guide to Birds of Eastern North America by David Sibley.