Photo © Larry Ditto

WILD THING

Louisiana Bound

Research seeks answers on migration of buff-bellied hummingbirds.

By Tony Henehan

Hummingbirds have fascinated me for as long as I can remember. I love to watch these tiny birds, barely bigger than a butterfly, zooming around to flowers and chattering at each other throughout the spring and summer.

I grew up in New York, where we get only one species of hummingbird, the ruby-throated. When I moved to South Texas, where I work as a Texas Parks and Wildlife Department wildlife biologist, I was delighted to see black-chinned and buff-bellied hummingbirds, in addition to that familiar ruby-throated.

Texas also offers uncommon wintering species like the rufous hummingbird and rare hummingbirds from Mexico like the green-breasted mango and Mexican violetear.

In the midst of all these jewels, though, my eyes keep returning to the buff-bellied hummingbirds.

Did you know that South Texas is the only place in the United States you can find buff-bellied hummingbirds? This species is categorized as medium-sized, a little over 4 inches long and weighing about 5 grams (as much as two pennies).

Hummingbird hearts beat up to 1,200 times per minute, so they require high-energy food (like nectar) to maintain their metabolism. In parts of South Texas, upwards of 90 percent of the buff-bellied diet is Turk’s cap, a red-flowered native shrub.

The buff-bellied hummingbird also exhibits an interesting behavior in the fall and winter — it migrates north along the Gulf Coast into Louisiana. The only other bird species that exhibits a similar movement is the groove-billed ani.

Why does the buff-bellied hummingbird migrate north in the winter? Do all buff-bellieds move north, or just some individuals? If so, is it the young that move north as they learn about their environment, or do the adults migrate, too? Do only birds in the northern part of the range migrate, or do buff-bellieds from Mexico migrate north as well?

The answer may surprise you. We really don’t know yet!

My research project will try to answer these questions. I’ll be banding individual birds and re-catching them later in the year to check their travels. Since April 2019, I have banded 133 hummingbirds from four species in the Rio Grande Valley; 52 were buff-bellieds. Banding efforts will continue throughout the year across the Rio Grande Valley and other parts of South Texas.

Hopefully, this mystery will begin to unravel over time. Stay tuned.