Scientists bring back animals from brink of extinction

Posted: Thursday, September 14, 2000

GRAND CHENIER, La. (AP) -- Alligator season opened throughout Louisiana this month, thanks in large part to the efforts of researchers at Rockefeller Wildlife Refuge.

Just 35 years ago, people rarely saw alligators in Louisiana. Three centuries of extermination efforts nearly pushed Louisiana alligators, considered vermin by most early settlers, down the one-way road to extinction.

Hunters killed about 3.5 million alligators in Louisiana between 1880 and 1933. By the 1950s, gators grew scarce. In 1962, the state abolished alligator harvesting and began a determined effort to return the king of the marsh to its rightful domain.

That's when Rockefeller researchers stepped into the picture. Until then, people knew little about alligator habits, reproductive capacity or life histories. Rockefeller biologists began intensive studies of these prehistoric beasts by observation, tagging and egg collecting.

Research enabled wildlife managers to develop a management plan. In 1972, the state reopened a limited hunting season in Cameron Parish. That year, 59 hunters caught 1,315 alligators. By 1981, alligators had sufficiently recovered so that Louisiana opened a monthlong statewide annual harvest.

Biologists now know how many alligators a specific habitat can support. Using this data obtained by Rockefeller researchers, state wildlife biologists can survey particular habitat types and estimate how many gators per acre that habitat can support. To trim surplus gators, the Louisiana Department of Wildlife and Fisheries issues harvest tags to landowners.

''The current Louisiana alligator population exceeds one million with an average annual population growth of about 10 percent,'' said Larry McNease, a Rockefeller biologist. ''Alligator harvests contribute about $8 to $12 million annually to the Louisiana economy.''

Each year, trappers harvest approximately 30,000 alligators during the September season. Trappers sell meat and hides. Leather from hides is used to make shoes, luggage and many other items.

Alligators represent a renewable resource and an economic boon to trappers. However, one wildlife recovery effort stands out purely for its altruistic vision. By the early 1960s, pesticides nearly eradicated pelicans from the Pelican State. Soon, the only representative of the state bird perched on a flag.

By 1961, only one nesting pair of brown pelicans remained in Louisiana. Even they disappeared by 1963. In 1968, Rockefeller researchers began working with Florida, which still maintained a remnant pelican population. Biologists brought some Florida birds to Rockefeller for study and breeding with the idea of reintroducing them into the wild.

The program worked exceeding well. Now pelicans thrive along the coast. The state population swelled to about 50,000.

Rockefeller researchers conducted similar programs with bald eagles. In about 1954, biologists counted only four eagle nests in Louisiana. By 1997, that figure skyrocketed to 118 with 165 native Louisiana fledglings joining the flock that year.

In recent years, refuge scientists turned their attention to the daunting problem of a disappearing coastline. The state loses about 35 square miles a year to coastal erosion. Already, the Gulf of Mexico reclaimed about 10,000 acres of the original 86,000 on the refuge. To combat this erosion, Rockefeller scientists study how to manage marshes through creating silt traps, such as old Christmas trees or replanting hardy grasses.

Several factors contribute to such devastating erosion. Years ago, companies dug canals to gain better access to vast marshes and rich resources. Canals opened huge areas to tidal fluctuations. Over the years, flushing tides, combined with periodic poundings by storms, ripped huge chunks from marshes.

To retain fresh water, people built weirs, or low dams, across many canals and bayous. However, fragile marshes require varying balanced water levels with some inflow and outflow. Many marine organisms need this brackish mixing to survive.

Canals allowed in excess salt water. Too much brine kills aquatic vegetation that holds marshes together. With nutria eating what salt water didn't kill, grassy areas deteriorate into mudflats. A strong tide could obliterate a mudflat overnight.

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