Master Naturalists: Fall migration busy time for Coastal Bend
Nov. 18, 2010 at 5:18 a.m.
By Paul and Mary Meredith
All sorts of birds - from many different summer territories, headed for many different winter territories - pass over Coastal Texas each fall and spring. Some migrations are well-known, like the hummingbird migration. Others aren't so well-known but are amazing.
WHAT HAWK-WATCHERS CAN SEE
Visitors to Nueces County's Hazel Bazemore Park on the Nueces River near Calallen can watch hundreds of thousands of raptors migrating each fall. Fall migrations are more spectacular than spring ones. Spring migrations include sporadic flights over the park.
Another hawk-watching location is Candy Abshier WMA on Smith Point on Galveston Bay's eastern shore. The numbers of hawks migrating over that area isn't as large as those over Hazel Bazemore.
In northern and mid-northern North America, raptors spend summer months spread from western to eastern coasts. They migrate each fall to their wintering grounds, some as far south as southern South America. Migrating means many flights of birds "funnel" over Mexico's "narrower" land mass. For example, flights from farther east in the U.S. move westward, closer to flights from farther west, to travel over Mexico. However, some eastern birds continue flying along the East Coast, through Florida, across to Yucatan to reach their wintering grounds.
Hundreds of thousands of raptors can be viewed roosting and flying over Hazel Bazemore Park, where the funnel narrows as birds approach Mexico. The funneling provides spectacular viewing for folks in the park. Large flights usually arrive from mid-August through mid-October. The largest number of raptors arrives during the second half of September. One hawk-watch organization's data shows over 700,000 hawks passing over Texas's Coastal area.
The most common species funneling over Mexico is the broad-winged hawk. Estimates say up to 95 percent of broad-wings migrate over Hazel Bazemore headed to Argentina
Raptor groups fly using thermals of warm air, called "kettles," helping them save energy by gliding as much as possible. Morning hours' warming of air forms kettles; and birds rise within them - like vultures do - then glide southward as they descend through the kettles. Some broad-wings rise to 5,000 feet on a thermal. A single kettle has reportedly contained a thousand birds.
WHAT YOU SEE
One wildlife photographer reported sighting 300,000 broad-wings migrating in one day, and a 40-mile-long flight. At Hazel Bazemore single kettles of 10,000 hawks are routinely reported. And single flights of 100,000 or more have been reported. Reported single day's total sightings have been 100,000 to 400,000. Reportedly, 750,000 broad-winged hawks once roosted there overnight because of a "monster" cold front.
Like hawks? Hazel Bazemore is a good place to set up a lawn chair and watch the raptor migration. Binoculars are useful, but not necessary, for bird identification.
Paul and Mary Meredith are master naturalists. Contact them at firstname.lastname@example.org.