What to watch for in August: Birds Heading South
Here’s the Central Texas bird forecast for the month, courtesy of Travis Audubon. Learn more about Central Texas birds and bird-related events for all ages at travisaudubon.org or by calling 512-300-BIRD. Follow us at www.facebook.com/travisaudubon
Bird watchers have been keeping records of birds’ arrivals and departures for their geographic areas for years. Austin is no different. Travis Audubon has bird records with data back to 1925 and it reflects this information in its seasonal checklist. So what are some species to watch for in August? A variety of shorebird species, Black-chinned, Ruby-throated and Rufous Hummingbirds, Yellow-bellied and Least Flycatchers, Yellow, Wilson’s and Black-throated Green Warblers, and Yellow-breasted Chats should start showing up soon. In particular look for flocks of Mississippi Kites in late August. They are on their way to South America where they will mostly winter south of Bolivia from mid-November to March. In the meantime enjoy the kites that now breed in Austin in neighborhoods like Northwest Hills.
The Buoy Bird
One of the migrants that begins returning to Texas in August is the Forster’s Tern. While some Forster’s Terns are year-round residents along the Gulf Coast, there is a large migrant population that moves through Texas in the spring and fall. They are mostly absent in the Austin area from mid-June to mid-August. Southbound migrants may have spent the summer in the prairie-pothole region of North and South Dakota or further north in the Canadian provinces of Manitoba, Saskatchewan, and Alberta. There are Forster’s Terns breeding in the western U.S. too, in parts of Montana, Washington, Oregon, Idaho, Wyoming, California, Nevada, Utah, and Colorado. This is the most common and visible tern in Austin, and it is seen here mainly from November through mid-May. It is associated with inland reservoirs during migration and winter, but its preferred habitat is marshy wetlands with lots of open water, whether on saltwater coastal islands, brackish coastal shorelines or freshwater inland lakes. Most of them winter along the coasts of the U.S., Mexico and Central America.
Boaters have an excellent chance of encountering a Forster’s Tern. This mostly white long-winged and long-tailed tern with a pale gray back and wings favors perches out in the water, such as on buoys and exposed drowned tree limbs. It also perches on bridges, pilings, and wires. Forster’s Terns rest and loaf alongside gulls and other tern species on the shore and mudflats if raised perches are not available. Unlike gulls, which will swim and rest floating on the water, terns rarely do.
In non-breeding plumage Forster’s Terns have a distinct black eye patch and pointed black bill. In August though they might still be in breeding plumage but changing to non-breeding, with a black cap becoming flecked with white, legs that are faded orange, and they may retain a partially orange bill. In March to May they should be transitioning to breeding plumage with a black cap that goes down through the eye, bright orange legs, and an orange bill with black tip. Males and females look alike.
One challenge is separating any tern from gulls. Gulls, of which the two expected ones in Austin are Franklin’s and Ring-billed, look heavier and less aerodynamic than terns which are more slender and have narrower, more angular wings. Most terns have pointed needle-like bills for catching small fish. Most gulls have rounded tails rather than the forked or notched tails seen in many tern species. Also gulls walk on the ground more, scavenging for a wide variety of foods with their stouter bills.
It’s really enjoyable to watch Forster’s terns foraging. They are buoyant flyers, coursing back and forth across the water about 20-25 feet up, with their bills pointing down as they look for fish. When fish are spotted the terns occasionally hover, but more typically just plunge dive into the water, to a depth of 1 foot. Small fish are usually swallowed as the terns fly back up to take another pass, while larger fish might be dropped about 10 feet from the foraging height, and recaptured. This may be repeated a few times and is thought to help prepare (soften?) the fish for swallowing. When fishing for their chicks, studies have observed that the terns select small fish, about 1.3 inches in length for one-week old birds, and 2 inch fish for older chicks. Although fish are the mainstay of their diet Forster’s Terns also pick arthropods from the water’s surface.
Fun Facts about Forster’s Terns
It can take a Forster’s Tern chick up to five days to hatch; the average amount of time is three days from the first crack in the shell to emergence. The chicks are semi-precocial. Their eyes are open and they are covered in down. Unlike precocial birds they don’t leave the nest for a few days, and are fed by the parents.
Forster’s Terns are more cold-tolerant than other North American terns, wintering farther north.
The Forster’s Tern is named for a German naturalist, Johann Reinhold Forster, who realized that the Forster’s Tern was a different species than the Common Tern which it closely resembles.
Some places around Austin to look for Forster’s Terns are Lake Travis, Lake Walter Long, Hornsby Bend and Lake Pflugerville. Binoculars are helpful as you check the buoys and watch for plunge-diving terns.
Upcoming Travis Audubon Events
Before you rule out birding in the August heat, check out the August calendar and register for a fun field trip, class or bird talk. Barton Springs, Commons Ford Ranch, Hornsby Bend, Reimers Ranch, Bracken Cave and Zilker Botanical Gardens are all sites for field trips this month. On Friday and Saturday, August 7 and 8th join the Purple Martin party to witness thousands of swirling swallows at their migratory roost site.
Compiled by Jane Tillman, Travis Audubon Volunteer
Resources: All About Birds, Birds of the World, the Travis Audubon Seasonal Distribution Checklist, The Texas Breeding Bird Atlas and Terns of North America by Cameron Cox.
