Photo credit © John C. Stroud 2005, All Rights Reserved.
As hummingbirds prepare for the autumn migration, each cardinal flower (Lobelia cardinalis) with its very tall inflorescence of sequential blooms provides a nectar source that is available from August into September. Photo by Larry Stritch.
By Kim Winter
Ruby-throated Hummingbirds (Archilochus colubris) make a spring migration from their over-wintering grounds in Mexico and Central America to the central and eastern United States and southern Canada. Their high energy needs require that abundant supplies of nectar be available throughout the migration corridor, which can range through thousands of miles of habitat. Although Ruby-throated Hummingbirds are well recognized as nectar feeders, they also eat spiders and tiny insects such as flies, gnats and aphids as a source of fat and protein. These foods help hummingbirds to nearly double their weight (from about 3.25 grams to 6 grams) before crossing the Gulf of Mexico. A single migration can become a nonstop flight of up to 500 miles over a period of 18 to 22 hours.
Wildflowers that appeal most to hummingbirds include species with red or orange coloration, long, tubular flower shape, and lots of dilute nectar. Some hummingbird favorites include native wildflowers such as trumpet honeysuckle (Lonicera sempervirens), scarlet beebalm (Monarda didyma), lemon beebalm (Monarda citriodora), wild bergamont (Monarda fisulosa), cardinal flower (Lobelia cardinalis), and trumpet creeper (Campsis radicans). Spring migrations of the Ruby-throated Hummingbird coincide with flowering periods of red buckeye (Aesculus pavia), clove currant (Ribes aureum var. villosum), and columbine (Aquilegia canadensis). The diverse Salvia genus, many of which are native to the western United States, offers many plants that are widely appealing to hummingbirds and other pollinators.
Some scientists believe that as many as 19 species of plants found in the eastern United States have co-evolved with hummingbirds, noting the relationships between the tubular shape of certain flowers and the length and shape of a hummingbird’s bill. The hummingbird laps up nectar by flicking its long, forked tongue deep within a flower at rates up to ten times per second. It forages while hovering airborne, inadvertently collecting pollen on its feathers and bill before darting off to its next meal. Its efficiency as a pollinator is comparable to that of a honey bee.
Ruby throated hummingbird feeding in a trumpet creeper (Campsis radicans). Photo by T.G. Barnes, University of Kentucky.
Red columbine (Aquilegia canadensis) is one of the first food plants that returning ruby throated hummingbirds depend upon during their spring migration northwards. Photo by Larry Stritch.
Fortunately, the Ruby-throated Hummingbird is abundant throughout its range and it has a total estimated population of over 7 million individuals. While it was hunted during the nineteenth century for its beautiful plumage, the Ruby-throated Hummingbird now enjoys protection from harvest through the Migratory Bird Treaty Act, which declares unlawful the taking, killing, or possessing of migratory birds. It is also listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Flora and Fauna of 1975 (CITES). Maintaining and protecting habitats and nectar plants along the migration route of the Ruby-throated Hummingbird should help to promote healthy populations of this beautiful bird well into the future.
Photo by T.G. Barnes, University of Kentucky.
For Additional Information
In the dog days of summer, ruby-throated hummingbirds sip nectar from scarlet beebalm (Monarda didyma). Photo by Joseph M. Schneid.