The ruby-throated hummingbird has to be one of most eagerly awaited birds among our migratory breeding birds. Who is not captivated by the acrobatic flight of hummingbirds, their iridescent colors and their tiny size.

The hummingbird family is one of the largest among birds with 328 recognized species. They are birds of the New World with the majority found in the tropics of Central and South America. In North America, only about 20 species occur regularly and only one – the ruby-throated hummingbird – breeds in eastern North America.

The ruby-throated hummingbird is one of the smaller hummingbirds with a typical one weighing a little more than 3 grams, about the weight of a penny. The smallest hummingbird is the bee hummingbird from Cuba, which weighs only 2 grams. On the larger side, the South America sicklebills and the sword-billed hummingbird weigh 12-14 grams, a little more than a chickadee. The largest of all hummingbirds is the aptly named giant hummingbird, which tops the scales at 21 grams, the weight of a tree swallow.

Ruby-throated hummingbirds spend the winter between southern Mexico and western Panama. In migration, some individuals undertake a Herculean, non-stop migration of 1,000 miles across the Gulf of Mexico. The birds have to put on extra fat to fuel this expensive flight. Feeding on nectar and insects, a ruby-throated hummingbird will double its weight before it departs across the Gulf of Mexico.

Recent observations indicate that some ruby-throated hummingbirds prefer to migrate along the eastern coast of Mexico to reach the United States, a longer but perhaps less demanding migration since these birds can feed along the way.

We have learned that ruby-throat migration is strongly temperature-dependent. Jason Courter and colleagues compared the arrival dates across North America using the now discontinued North American Bird Phenology Program (1880-1969) with more recent data from the Journey North program (2000-2010). The authors found that ruby-throats in the more recent period are arriving between 11 to 18 days earlier, depending on latitude.

The authors also found that short-term variation is occurring in arrival dates. Surprisingly, ruby-throats in our area tend to arrive later in warm springs. The authors believe that the hummingbirds are extending their migratory stopovers in the southern states during those years.

Once in the United States, ruby-throated hummingbirds disperse widely. The breeding range extends from eastern Texas along the Gulf Coast to Florida (including all but the southern tip of the Florida peninsula) and north in the east to Nova Scotia, New Brunswick and Labrador and west to Minnesota, then spreading westward in the Canadian prairie provinces, stopping just shy of British Columbia. The ruby-throated hummingbird certainly has a broad nesting range. It’s range is the largest of any hummingbird breeding in North America.

Hummingbirds are specialized to feed on nectar. A number of plants and hummingbirds have evolved mutualistic relationships. These plants produce sugar-rich nectar, which attracts hummingbirds. As the hummingbirds feed on the flower, pollen attaches to the hummingbird’s head and bill. When the hummingbird visits another flower, some of the pollen it is carried is transferred to the female part of the flower and fertilization is assured. Some plants therefore “pay” hummingbirds in nectar in return for pollination services.

Most long, tubular flowers are attractive to hummingbirds. Bee balm is particularly recommended. Of course, a hummingbird feeder is an easy way to attract hummingbirds as well. Choose a feeder with a wide mouth to make cleaning easy. You can buy so-called hummingbird food to dissolve in water. On the other hand, you can save some money and make your own. Just mix four parts of water to one part of table sugar and bring to a boil. When the sugar is dissolved, cool and then fill your feeder. You can store the excess in your refrigerator for a couple of weeks.

Herb Wilson taught ornithology and other biology courses at Colby College. He welcomes reader comments and questions at whwilson@colby.edu

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