Photo: Blackpoll Warbler, Kevin Sim/Audubon Photography Awards
Betsy Martin
Hurricanes Helene and Milton posed special challenges during this fall’s migration. Migration ecologist Andrew Farnsworth of the Cornell Lab of Ornithology estimated that 150 to 275 species were in the midst of migration during the hurricanes, which interrupted the migration of more than 100 million birds crossing over Alabama, according to the Washington Post.
Even without hurricanes, migration poses challenges that defy imagination. Take, for example, the Blackpoll Warbler (Setophaga striata). The Blackpoll Warbler does not breed in northern Virginia, and only shows up here while migrating to and from its breeding grounds in conifer forests far north in Alaska and Canada and its wintering grounds in South America.
This small bird weighs less than half an ounce, about as much as two quarters. Yet, it undertakes the longest migration of any North American warbler. Some individuals travel almost 5,000 miles from Alaska to Brazil. In fall, they travel south and southeast through Canada and the northeast U.S., and collect along the coastal plain between Nova Scotia and Cape Hatteras, NC. Then, it’s believed (the experts aren’t really sure), they head south and southeast over the Atlantic, and fly nearly 2,000 miles to Puerto Rico, the Lesser Antilles, or northern South America. This may involve an 88-hour nonstop flight over the open ocean! They ride northeast trade winds to direct their flight toward South America.
Sassafras drupes are a favorite of early fall migrants, such as Eastern kingbirds. The red pedicels signal the fruit is ripe. Photo: Betsy Washington
To accomplish this amazing feat, Blackpoll Warblers nearly double their weight before setting out. They add fatty fruits to their diet of bugs and caterpillars. They eat any late summer or fall fruits, but it’s the native ones that have the high fat content they need to sustain them on their long journey.
Blackhaw. Photo: Courtesy of Dyck Arboretum of the Plains
Migrating birds make periodic stopovers to eat and replenish their energy reserves. Make your yard a wildlife sanctuary for them by planting native fruiting shrubs, trees, and vines. Good choices for migrants that also make nice landscape plants in northern Virginia include Arrowwood, Blackhaw, or Possomhaw viburnums (Viburnum dentatum, V. prunifolium, V. nudum), Virginia creeper (Parthenocissus quinquefolia), Silky, Gray, or Flowering Dogwood (Swida amomum, S. racemosum, Benthmidia florida), Spicebush (Lindera benzoin), American beautyberry (Callicarpa americana), and Sassafras (Sassafras albidum). Bayberry’s (Myrica cerifera) wax-coated fruits can only be digested by a few migrant species (Yellow-rumped warbler and Tree swallow) so this plant is not useful to most migrants. Fruits of other native fruiting trees, such as American holly (Ilex opaca) and Hackberry (Celtis occidentalis) ripen too late to be useful to fall migrants, but are good food sources for wintering species. All of these shrubs and trees set more fruit if planted where they get sun. You can find out more about their characteristics, requirements, and eventual size here.
Fall-fruiting native shrubs and trees not only provide nutritious, fatty berries for birds, but also display beautiful fall color. That’s not for our benefit: what’s called foliar fruit flagging is the way the plants signal to birds that fruits are ripe and ready for plucking—just in time for migration.
Catch up on past Wildlife Sanctuary Almanac articles here.