Hummingbird Migration Stopovers & Flights
Ruby-throated Hummingbirds are reaching their peak migration period across the eastern half of the United States (photos by Paul Konrad).
As hummingbirds are migrating and making crucial stopovers during September, it is interesting to learn more about the biology and energetics of how some Ruby-throated Hummingbirds prepare for long non-stop fall migration flights. During a study of Ruby-throats making a stopover in southern Alabama, one of several interesting pieces of information was discovered that permitted researchers to estimate that the “average” Ruby-throated Hummingbird has a nonstop migration flight range of about 1,320 miles.
The Alabama study found that some Ruby-throats effectively double their body mass during feeding bouts during a migration stopover, in advance of making long-distance migration flights. To study these and other topics, researcher Theodore Zenzal and his colleagues captured, banded, measured, weighed, and released 2,729 Ruby-throated Hummingbirds during 5 fall migration periods at Bon Secour National Wildlife Refuge, located on the southern tip of Alabama adjacent to the Gulf of Mexico.
After collecting weight and age data about each hummingbird they caught, the researchers used a computer program to estimate the Ruby-throats’ flight range based on birds’ body mass and wingspan. The resulting information provided their estimate that the “average” Ruby-throated Hummingbird has a flight range of about 1,320 miles. Using this method, they also predicted that older hummingbirds and males were able to travel farther than younger hummingbirds and females.
The flight ranges that researchers calculated mean that most Ruby-throats would be able to migrate directly across the Gulf of Mexico to the Yucatan Peninsula of Mexico, a distance of less than 700 miles. While it is not yet substantiated that Ruby-throated Hummingbirds migrate across the Gulf of Mexico in numbers, new methods of tracking hummingbirds should soon provide more information about that continuing question. For now, researchers believe most Ruby-throated Hummingbirds migrate around the Gulf, funneling along the coast to locations like Rockport, Texas and the Corpus Christi area, then south.
Male Ruby-throated Hummingbirds tend to migrate earlier than females in many areas, with young of the year averaging slightly later migration times.
The team’s research documented that at their southern Alabama study site, fall hummingbird migration begins in late August and continues into late October – but peaks during September. It also showed that older Ruby-throated Hummingbirds migrate ahead of younger ones, with older hummingbirds arriving earlier and in better physical condition. Older birds also arrived earlier, had larger fuel loads, and had shorter stopover durations than younger birds.
This information is probably quite standard for Ruby-throated Hummingbirds that make migration stopovers from Florida to Texas adjacent to the Gulf Coast, where these tiny birds feed in earnest to increase their body mass so they can make a long-range flight to wintering areas in southern Mexico and Central America. The Alabama research team’s research was published in the scientific journal, The Auk, and is referenced below.
Of course, the need for good sources of sucrose sugar during migration makes every hummingbird feeder all the more important, especially during migration periods. Ruby-throated Hummingbirds have steadily increased in numbers according to the annual Breeding Bird Survey, and the increased availability of nectar feeders and flower gardens have been singled out as contributors to the continuing population increase.
With that in mind, be doubly sure keep your sugar-water nectar fresh, and your feeder filled. And likewise, in the western half of the United States and southern Canada, watch for the variety of hummingbirds that may visit your feeders that will be looking for fresh sugar-water nectar during fall migration stops.
Most of this information was gleaned from an original article published in the All About Birds website by the Cornell Lab of Ornithology at Tiny Hummingbirds’ Incredible Migration | All About Birds All About Birds and the original scientific article published in The Auk 133(2): pages 237-250 at Stopover biology of Ruby-throated Hummingbirds (Archilochus colubris) during autumn migration.
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