Back in the summer of 2012 Deborah and I really became committed to hummingbirds. We had the pleasure of watching a female ruby-throated hummingbird (whom we named “Hubert”) swoop into our yard in May and take over all of our flower beds. We put up a nectar feeder for Hubert and watched her battle other ruby-throats for possession of the feeding resources, and then we watched her nurture her mirror-imaged fledgling into robust independence. When Hubert flew off in late September on her migration to the south, both Deborah and I felt like we had lost a friend.
In the summer of 2013 we had another female ruby-throat that behaved much like Hubert (perching on the long, utility line out by the street, keeping watch on her flower bed and nectar feeder domain). Based on the scientific literature that documents the species’ preferential return to both their summer and winter locations, we assumed that this active hummingbird was Hubert.
The summers of 2014 and 2015 were not active hummingbird seasons for us. Possibly it was too cool or too wet for them, possibly the deer impacted destruction of our bee balm patch (the centerpiece of our hummingbird flower garden!) left insufficient natural nectar sources to attract them, or maybe there was a lingering aura of the ferocious territorial defenses that Hubert mounted against any intruder that kept passing hummingbirds from dropping into our yard.
We replanted the bee balm in our deer-controlled yard area. The wooden fence and the high line of flapping, plastic pennants has worked for two years now to keep the deer from our deck-side flower bed and small vegetable garden. This year the bee balm grew tall and thick and was brilliantly flowering in mid-June, and, sure enough, about the third week in June we got not just one but three hummingbirds (two females and a male).
Deborah hung her nectar feeder out on a line right next to the bee balm and our active trio stuck around for the rest of the summer (joined eventually by another female-plumed individual whom we assumed to be a fledge of one of the females).
On September 1, the male vanished from our yard. We assumed that he left on his long and arduous migration south. In mid-September two females were still coming into the feeder and perching on the thinning tree branches of the maples and spruces that surround one side of the yard. As of two days ago (September 27) only one female was still active in our yard. I am sure that we only have a few more days before she takes off on her long journey south, too.
Migration is an absolute requirement for most hummingbirds. They are not able to eat seeds or fruit or other food that might persist through a cold, temperate zone winter. They are nectar fueled carnivores that must have abundant sources of flowers and insects throughout the year. The ruby-throats that summer around here spend their winters in the dry forests, citrus plantations, and scrub forests of southern Mexico, Guatemala, Honduras, Nicaragua, Costa Rica, and northern Panama.
Hummingbirds are solitary birds. They do not form migratory flocks for a number of very logical reasons. A single hummingbird is very inconspicuous where a flock might attract the attention of predators. Also, hummingbirds have to regularly stop and feed along their migration routes and traveling alone means shorter lines at potential nectar sources and more insects and spiders in whatever habitat they happen to visit.
Hummingbirds fly very low on these long migrations. Typically they are seen just above the tree tops or just over the surface of any body of water (like the Gulf of Mexico!) that they might have to cross. Often they wait for favorable winds and weather fronts to assist them along, but frequently they have been observed flying into very severe headwinds. Migration takes one to four weeks, and they fly an average of twenty to twenty-five miles each day. The five hundred mile span of the Gulf of Mexico, though, has to be done in one stretch unless the birds happen to pause on an off-shore oil derrick or passing shrimp trawler. Most flying is done during daylight and the nights are used for resting. Males and females and mature and immature birds all have their own general times for migration. Males typically migrate several weeks before females, and older, mature birds, probably because they build up critical body fat reserves more rapidly than younger birds, tend to migrate before the younger individuals.
About twice as many ruby-throats start the Fall migration south as finished the Spring migration north. Migration takes a heavy toll on these birds, but their robust reproductive potential continuously compensates for the yearly declines.
Individual ruby-throats tend to take the migration path that they initially followed on their first flight south. They return to both their wintering sites and summer breeding sites with great consistency and accuracy. On the southward migration the birds fly over land in greater numbers (down the Appalachians, across the Gulf Coast, down over Texas, to Mexico and Central America). This is possibly due to the potential occurrence of fall hurricanes over the Gulf of Mexico. It has been speculated that individual birds whose behavior emphasized flying over the Gulf in the fall were selected out of the population by encounters with these catastrophic storms. On the spring northward migration, though, hurricanes are unlikely over the Gulf and the “short-cut” from the Yucatan to the U.S Gulf Coast is the preferred pathway for these birds.
The ruby-throats begin their northward migrations often as early as January. Many of them have gathered in the Yucatan Peninsula by late February where they feed avidly on abundant insects and spiders. Each ruby-throat doubles its weight (going from just over 3 grams to just over 6 grams) during this period of feasting. Then, over a period of three months, wave after wave of ruby-throats cross the Gulf (the 500 mile trip takes 18 to 22 hours) ending up scattered across the U.S. Gulf Coast from Texas to Florida. When they get to land they weigh about 2.5 grams!
These ruby-throats must then feed and get back to their migration weights. They then work their ways steadily northward at their pace of about twenty or twenty-five miles per day. The Western Pennsylvania birds will arrive here in late May just in time for the riot of spring flowers and the emergence of the early summer insects.
On average a wild ruby-throated hummingbird will live for three or four years. One banded, wild ruby-throat, though, lived for just over nine years! That means that that individual made seventeen or eighteen migrations during its lifetime! If that bird flew from Pittsburgh to Panama its migration would be two thousand miles each way! For a bird that only weighs as much as a penny, that’s a lot of miles to fly!