The Fascinating Hummingbird Migration Journey
Banding has provided us with information on hummingbird migration
("Banding" means trapping a bird and wrapping a tiny numbered strip of
aluminum around one leg).
Most hummingbirds that spend their summers in North America
return to more temperate climates for the winter. As sunlight and
the food source of nectars and insects diminish and the temperatures
begin to drop, the hummers will start their journey south to Central
America. Most North American hummingbirds can tolerate cold
temperatures for a few days as long as there is sufficient food
available. Many species that migrate to the U.S. travel impressive
distances.
Ruby-throat Hummingbirds, for example, may travel as many as
2,000 miles between Canada and Panama. The trip includes a non-stop,
500-mile flight over the Gulf of Mexico (see
map).
Hummingbirds by nature are tropical creatures. They have been
programmed to move north in the spring to exploit the renewed food
sources and nesting sites, while escaping the intense competition for
the same in the tropics. It is believed that this process began
with the end of the last ice age.
Until recently, hummingbirds were among the least studied of
all wild
birds. The interest in these little jewels has been increasing
in both the scientific community and with bird
watching enthusiasts. Much is being learned from an increasing
number of hummers being banded. This is currently the only way to
identify individual hummingbirds. Hummer species are studied by
gathering data on large numbers of individuals. More and more is being
learned about the hummingbird migration cycle using this new
information.
Since there are as many hummingbird migration strategies as there are
species of hummingbirds, I will focus on just one. Living in the
Northeastern US, my interest lies mainly with the Ruby-throated
hummingbird.
Ruby-throated hummingbirds are solitary creatures that spend their
winters in southern Mexico and Panama. They do not migrate in flocks. Ruby-throats
will begin moving north as early as January. They will eat large
amounts of insects, nearly doubling their weight, to grow from about 3
grams to 6 grams.
The weight gain is necessary to give them the energy needed for the
journey across the Gulf of Mexico. The nearly 500 mile, non-stop
flight will take 18 and 22 hours, depending on weather conditions.
The first males typically leave a few weeks before the first females.
The species migration is spread over a few months. This reduces the
possibility of species destruction from any single weather event.
Once in the US, the hummingbird migration will continue at a rate of
about 20 miles per day following the early blooms of the flowers that
the Ruby-throats prefer as a food source. The northern migration is
usually completed by the end of May. Banding studies have shown that each
bird will return to the area where it hatched, even returning to
the same
nesting sites year after year.
Ruby-throats do not do well in cold temperatures. So to avoid the cold,
lack of blooming flowers and reduced insect populations they move
south. The southern pattern resembles that of the northern migration. Some
hummingbirds will begin their trip south as early as July, while
others will wait until August or even September to leave.
It is likely that the birds you see at your
bird feeders in August are on their migration from farther north
and not the same birds that you saw at your feeders earlier in the
summer.
It was once thought that leaving your hummingbird
feeders up would delay the hummingbird's migration. Studies have
shown that reduced sunlight is what triggers the ruby-throats to start
their migration and not reduced food sources. If you remove your
feeders early, the hummers will simply feed elsewhere, reducing the
chance that they will return to your feeders in the spring.
Understanding
hummingbird migration will help you decide when to put out your
hummingbird feeders.
Click here for even more facts
about the hummingbird.
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