Hummingbirds spend the winter in Central America or Mexico, and migrate north to their breeding grounds in the southern U.S. as early as February, and to areas further north later in the spring. The first arrivals in spring are usually males.
Photo courtesy of the author
Although there are differing views in the birding community as to what triggers the start of migration, it is generally thought that hummingbirds sense changes in daylight duration, and changes in the abundance of flowers, nectar and insects. Instinct also plays a role in making the decision to migrate.
During migration, a hummingbird's heart beats up to 1,260 times a minute, and its wings flap 15 to 80 times a second. To support this high energy level, a hummingbird will typically gain 25-40% of their body weight before they start migration in order to make the long trek over land, and water. They fly alone, often on the same path they have flown earlier in their life, and fly low, just above tree tops or water. Young hummingbirds must navigate without parental guidance.
Hummingbirds fly by day when nectar sources such as flowers are more abundant.
Flying low allows the birds to see, and stop at, food supplies along the way. They are also experts are using tail winds to help reach their destination faster and by consuming less energy and body fat. Research indicates a hummingbird can travel as much as 23 miles in one day.
The spring migration can be hard on the hummingbird population as they move north from their winter homes in southern Mexico and Central America.
Strong cold fronts moving south over the Gulf of Mexico make flying difficult as the birds deal with headwinds and heavy rain, over long distances with no shelter. Food is non-existent over the open waters.
First arrivals in the spring, usually males, can be seen in Texas and Louisiana in late February to mid-March. Our first hummers usually arrive here in East Texas in mid-March, when we see 1-2 at a time. In more northern states, first arrivals are not until April or May.
Stops along the way may be for a few minutes, or a few days at more favorable locations with abundant food supplies.
Hummingbirds "heads down" storing energy for the fall migration
Many hummingbird specialists feel that, in order to avoid cold weather and the scarcity of food when flowers stop blooming and insects stop flying, Ruby Throats migrate to the south. Others feel that the shortening days of summer trigger the migration instinct.
They migrate as individuals, not as a flock. Moving at 20-25 miles a day, each hummingbird must judge the distance it has to travel, and the time by which it needs to be in position to make the final flight into Central America.
By August and September, hummingbirds are moving south in great numbers, refueling their bodies in the early morning, traveling midday, and foraging again in the late afternoon to maintain their body weight. A hummingbird will gain 25-40% of their body weight before they start migration. The number of birds migrating south is larger than the numbers that migrate north, since the fall migration includes newly hatched birds as well as older adults.
August brings lots of activity here in East Texas, when we have 10-20 birds at a time, with peak numbers in early September when we typically spot as many as 25-40 hummingbirds at a time as part of the fall migration. Most are Ruby Throats, with an occasional Rufous in the mix at the feeders.
Ruby Throats gather in Florida, Louisiana and along the South Texas coast in September in preparation for the final push to the south, either over the Gulf of Mexico or via an overland route through Mexico to their winter home in Central America. It is felt that more Ruby Troats choose an overland route when leaving Texas as opposed to a flight across the Gulf, possibly due to the dangers of fall hurricanes.
Hummingbirds are overwintering on the Gulf Coast in greater numbers than in the past, and many can be found at feeders in South Texas and South Louisiana during mild winters.