See the Top 10 U.S. natural migrations.
Sanjayan's Fascination with Migration
The Nature Conservancy's lead scientist Sanjayan's fascination with natural migrations came from his own migratory childhood - when his family moved from Sri Lanka to Africa, back to Asia, and then ultimately to the United States. "I am fascinated with things that depend on moving for a living," he says.
May means spring, and that means the animals of the world are in motion again — flying, swimming, running and crawling to their summer homes and breeding grounds. The Nature Conservancy is celebrating this annual pageant of nature with a listing of the “Top Five Must-See Migrations” in Texas.
“Texas is a critical crossroads for so many bird species as they wing south to wintering grounds and then back north again," explains John Herron, director of conservation for The Nature Conservancy of Texas.
"Countless species fly and feed on the long trip from the tropics to breeding grounds in North America. In Texas each spring, we get to witness that epic journey as our trees and fields leaf out, providing food and sanctuary for millions of songbirds, hawks and wading birds, all pushing relentlessly north to create the next generation of birds. And as people experience that migration spectacle, we develop a bond with nature and connect a new generation with the wonders of the natural world.”
The golden-cheeked warbler migrates between South and Central America and Texas. These splendid black, white and gold songbirds only breed and hatch their young in Texas’s Edwards Plateau, opting for old-growth Ashe-juniper trees to nest in. They migrate to Texas beginning in early March, then depart for their wintering ground in Central and South America in mid-June. Federally endangered in the United States and listed as endangered by the IUCN, the golden-cheeked warbler is threatened by increased urbanization, habitat loss and nest parasitism by cowbirds. In their winter range, they may also be imperiled by a widespread Mediterranean fruit-fly eradication program.
The Nature Conservancy is actively restoring habitat for the rare bird at several Hill Country preserves, including Barton Creek Habitat Preserve, which is frequently open to visitors wishing for hiking and birdwatching.
The migratory whooping crane is one of the most endangered birds on the planet, with a population that fluctuates, but rarely numbers fewer than 300 wild animals. The surviving wild flock breeds at Wood Buffalo National Park in northern Alberta and migrates 2,400 miles south to winter haven at just a handful of locations along the Texas Gulf Coast. There, the birds while away the winter months feeding on blue crabs and other marine life. Along their migration route, whooping cranes rely on prairies and wetlands in Nebraska, Kansas and other states for stopover sites.
Because all the birds of this surviving wild flock breed and winter in close proximity, they are vulnerable to events, such as oil spills or wildfires that could potentially decimate the population. To help ensure the long-term survival of whooping cranes, many groups have worked to protect and reintroduce the species in other parts North America through captive breeding and reintroduction programs.
One of the largest colonies of warm-blooded mammals on the planet makes its seasonal home near the small town of Mason. Each May, the Eckert James River Bat Cave Preserve welcomes millions of female Mexican free-tailed bats, who use the cave to birth and raise pups before returning to Mexico in October.
While tranquil during the day, the cave grows into a bustling hive of activity in the evenings. In the hours before sunset, the bats grow restless—hundreds flutter and chirp around the mouth of the cave. A stream gradually emerges, spiraling upward to form a living “tornado of bats” that towers high above the cave. Eventually, the bats at the top of the spiral break off into columns that stream out over the countryside to feed—every night, each bat consumes nearly its body weight in mosquitoes and crop pests like cutworm and corn borer moths. The preserve is open to the public seasonally between 6 p.m. and 9 p.m. Thursdays through Sundays for interpretive tours. Call (325) 347-5970 for information and directions.
A small songbird with distinctive white “spectacles,” the black capped vireo as added the federal endangered species list in 1987. The song of this charming songbird has been called musical, emphatic, husky, harsh, chattering, restless, hurried and even angry. It’s also complex, drawing from a repertoire of syllables about ten times larger than those of other vireos—some 1,700 different notes have been identified in the species’ repertoire. Breeding in Texas, Oklahoma, Nebraska, and northeast Mexico, the birds nest in dense low thickets and oak scrub, usually on rocky hillsides. They arrive in Texas between late March and mid-April then depart for their winter grounds along the west coast of Mexico by mid-September.
At present, the breeding range extends from Oklahoma (where populations are spotty occurring only in 3 counties) south through the Edwards Plateau—where it can be seen at Conservancy preserves and state parks—and Big Bend National Park, Texas, to wintering grounds along the west coast of Mexico from southern Sonora to Guerrero.
The monarch butterfly’s distinctive coloring makes it one of the most easily recognized insects in the sky. Native to the Americas, the monarch has colonized such far-flung locales as western Europe and Australia. The life of the monarch butterfly is marked by a yearly generational migration. North America's western population migrates to California, while the eastern population—which can range as far north as Canada—migrates south, funneling through Texas and hugging the Gulf Coast down into Mexico.
At the terminus of the southern migration in central Mexico, tens of millions of butterflies overwinter in less than 20 sites, gathering in 20-30 million per large roost. They begin to disperse in late February and early March, mating and then flying north, usually making it to Texas before laying their eggs on milkweed plants. The next generation continues the migration, leapfrogging north until the third or fourth generation arrives as far north as Canada in May and June. This final generation migrates up to 2,200 miles back to Mexico, arriving in early November. They begin migrating singly, and then slowly gather into flocks as they converge upon roosting sites. During these migratory periods, monarch butterflies can be found on a variety of Texas locations, including Dolan Falls, Independence Creek and Fred and Loucille Dahmer Caddo Lake preserves.February 11, 2011