HUMMINGBIRD Migration

Hummingbird Migration Facts

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Migration of the ruby-throated hummingbird has been an inspiration and a wonder and a scientific puzzle for years. Shrimp fishermen and workmen on oil rigs reported that they found ruby-throated hummingbirds far out in the Gulf of Mexico (100 and 200 miles) where they did not belong. There were sightings along the coast of hummingbirds skimming fast over the water onto shore – annually – in step with migration cycles. Where did they come from?

Each hummingbird species has its own migration strategy, and it's incorrect to think of "hummingbirds" as a single type of animal, all alike. This article will discuss Ruby-throated migration, because it's likely that more people see that species than all the others in North America combined, and its dynamics are similar to other species, although the dates and locations vary. An exception is Anna's Hummingbird, which typically does not migrate but may wander up- and downslope following seasonal food resources.

As independent as Ruby-throated Hummingbirds, Archilochus colubris, appear to be on the breeding grounds--chasing each other constantly as they defend territories and feeding stations--it's hard to imagine they would tolerate each other enough to flock together during migration. In fact, what seems to happen is, because the all are migrating at about the same time, they end up being in about the same places. In early September, for example, huge numbers of hummingbirds gather along the Texas Gulf Coast near Rockport, Corpus Christi, and other sites. When they have put on a store of fat and conditions are right, the hummers begin begin leaving a few birds at a time, streaming out across the Gulf on their way to the Yucatan Peninsula. Technically, this is not flocking behavior.

They all nest in the north and travel great distances every year to reach their southern homes. The ruby-throated hummingbird lives throughout the East Coast and is famous for crossing the Gulf of Mexico. The calliope hummingbird is famous for being the tiniest of all birds who make long migrations.

This area has long been known as a hawk migration site and the data contained in this study were obtained in addition to the hawk count by volunteer observers. Data concerning weather were gathered from that taken for the hawk count. In order to maximize the view of the sky, the main site for counting is a parking area at the southwestern corner of the park. Hummingbirds were counted, hour by hour, as they flew past the ground-based observer(s) from 1976 - 1988. From 1989 - 1990, the newly erected observation tower (13 meters tall) was used for counts. Care must be taken to distinguish the rapid and difficult-to-detect hummingbirds from the migrating dragonflies and large bees also flying through. All observers were experienced enough to make this distinction. Coverage was most consistent from 1983 - 1997.

Occasionally Ruby-throated Hummingbirds, Archilochus colubris, that are ill or weak--or perhaps even some that fledge very late in the fall--will not migrate. Most of these birds are likely to die, perhaps because they are already ill, from the cold, or from other causes. Very rarely a RTHU will spend the winter in North America, but except for those few RTHUs wintering in south Florida or in the Gulf and Atlantic coastal statesmost all winter hummers are Rufous Hummingbirds or some other western species.

Once in North America, migration proceeds at an average rate of about 20 miles per day, generally following the earliest blooming of flowers hummingbirds prefer. The northern limit of this species coincides with that of the Yellow-bellied Sapsucker; if the earliest males arrive in Canada before sufficient flowers are blooming, they raid sapsucker wells for sugar, as well as eat insects caught in the sap. The northward migration is complete by late May. Banding studies show that each bird tends to return every year to the same place it hatched, even visiting the same feeders. See the Ruby-throated migration map for the species' range and earliest arrival dates.

Migrating birds of all kinds have adapted to the weather and wait for favorable winds. The ruby-throated hummingbird takes advantage of tail winds constantly. Research in the Appalachian Mountains of Pennsylvania showed that migrating hummingbirds appeared in greater numbers when the winds blew favorably and even more when the winds were stronger.

Ruby-throated Hummingbirds, Archilochus colubris, arrive at different times in different parts of North America, usually showing up in the Gulf Coast states well before appearing in Canada. The map below gives you an estimate of when to expect the first arrivals in a typical spring. Note that hummer arrival dates are not particularly affected by year-to-year differences in local weather.

Calliope Hummingbird Migration -- Breeds in western mountains as far north as central British Columbia. Spring migrants arrive in southern California in early March. Arrives in Oregon in early May. Birds may not arrive in Idaho and Montana until mid-or late May. Fall migration is early. Migrating birds can be seen in Arizona and New Mexico.

Ruby-throated hummingbirds have an urgent drive to reach their breeding grounds and sometimes arrive before the flowers bloom - surviving on insects and sugar water provided by kindly humans.2 They will only stay in one place, during migration, for an average of 7 – 14 days. The first arrivals in spring are usually male and they may be seen as much as three weeks before the others. It can be that this protects the females and young because they follow the bright plumage of the male and find a ready food supply. If a northbound male hummingbird finds an ample supply of flowers and nectar he may be enticed to stay and establish a territory and therefore attract females and competition from other males.

The East Coast range of the ruby-throated hummingbird broadens out as far as all the deciduous forests. The forests are rich in flowers and insects and provide an unusual source of food for this bird – tree sap. The farthest north that the ruby-throated and Rufous hummingbirds will range is directly related to the Yellow-bellied Sap Sucker.8 The Sap Sucker bores holes through the tree bark and the sap that weeps out of the “wells” provide food for both of these hummingbirds.

In the fall there is an instinctual clock that tells the hummingbirds when to head south. People still disagree over the precise mechanism within the bird that causes this. Most sources say that every expert agrees that food supply is not a factor and there is no reason to take down hummingbird feeders to stimulate migration.

An accepted fact that is not a theory shows that some Rufous hummingbirds have evolved. There is a documented shift in their migration pattern. A significant population now winters in the United States - along the Gulf Coast between Florida and Texas. They no longer return to Mexico. A change in habitat may be the determining factor that has attracted them. The Gulf Coast used to be forested. Now it is host to flowering shrubs and herbs.

One theory explains the new “winter home” developed because lost or misdirected Rufous hummingbirds found refuge when they reached the East Coast and finally turned south. They did not perish from their mistake and may have passed the new migration destination on to their young.