Monday, March 16, 1998
Because we were unable to catch a glimpse of a few of the animals that are common to the wetland areas that we toured yesterday, we made a return trip to the same zoo we briefly visited in January. We knew this would be a great place to learn more about all of the native inhabitants of the wetlands, and that this would also be a good way to obtain some close-up photos of animals who were a little camera shy the day before.
The Audubon Zoo is one of the top zoos in the country and features a 58 acre Louisiana Swamp Exhibit where we saw some new faces and a few familiar ones with long snouts and sharp teeth. Even though the alligators in the exhibit were far bigger than the ones we got close to yesterday, we felt far less afraid when they flashed a toothy grin for our camera today (knowing they couldn't get to us).
Alligators grow about a foot every year until they are 6 years old, and only grow an inch or two each following year. As a result of conservation measures started in the state in 1963, the alligator population has been rising and there is now an abundance of alligators in Louisiana. This increase in the number of alligators is actually considered to be a benefit. Alligators help control the population of another common resident of these areas, the nutria.
Some people consider the nutria to be a nuisance because they damage marshes, swamps, and agricultural fields, but many locals like them and hunt them for food and their fur. Nutrias are native to both Central America and South America. They were first introduced to this region in the 1930s to create a fur industry. Farmers bred the nutrias and kept them confined in cages. The animals are thought to have been accidentally released into the environment during a hurricane.
Without natural predators, their population increased very rapidly. Although the nutria quickly multiplied, the resident muskrat greatly declined in numbers. Today, the muskrats have found themselves on the losing side of a competition for food and shelter with the invading nutria.
While on yesterday's tour, we gave a short ride to one of these semi-aquatic rodents that look like a cross between a beaver and a muskrat. We were surprised at the size of the nutria. Most nutrias are about 35 inches long and weigh between 15 and 25 pounds. Four of their toes on their back feet are webbed, which makes them excellent swimmers.
At the zoo, we were also finally able to see a live Louisiana black bear. (If you recall, we tracked them unsuccessfully in White River National Wildlife Refuge on January 12.) The Louisiana black bear is one of the largest and heaviest wild mammals living along the Mississippi River. Black bears can grow to be over 6 feet tall and weigh nearly 600 pounds. They feed on grass, berries, fruits, seeds, roots, insects, fish, frogs, eggs, and carrion (dead animals). Bears used to live along the river, but hunting and habitat changes have now made the bear a rare animal in these parts.
As you can see, changes in the habitat and alterations in the food web can dramatically alter the population of some species. Can you think of animals in your region that are affected by changes in the environment? How do you think human activity contributes to these changes?
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