Wildlife

It is certain that a storm with winds of 225 kmph (140 mph) will immediately kill some fish, birds, and other animals as it passes through their habitat. Surprisingly, however, studies have shown that the passing of Hurricane Andrew actually provided benefits to some wildlife species while barely affecting others. Sweeping through the Atchafalaya Basin, the winds of the storm cleared much of the canopy in the bottomland hardwood forest. This disturbance allowed more sunlight and other nutrients for a greater variety and number of plants to grow and, ultimately, provided small mammals like white-footed deer mice, and amphibians, and reptiles with more food.

Populations and growth of larger mammals in the Atchafalaya Basin, such as the white-tailed deer, seemed not to be affected at all by the hurricane. The mixed hardwood forest, sustaining more damage than the cypress-tupelo swamps, provided more forage opportunities for deer after the hurricane. Over time, however, this increased forage will decrease as mature canopy trees become reestablished and shade out the understory. Further research will show if alternative management, such as clearing debris in the forests after a hurricane, would enhance the habitat of white-tailed deer in years following storms. (Figure 19)

Birds in the Atchafalaya Basin were affected more significantly by Hurricane Andrew. Numbers of resident birds-those that live in an area year-round-dropped immediately after the hurricane, as individuals, their nesting places, and habitat were battered by the high winds. But studies have shown that any actual mortality caused by the hurricane was not a negative factor for long; surviving residents and birds from the surrounding forest soon began repopulating the empty areas.

The northern parula, a Neotropical warbler, was one bird directly affected by the storm. This bird uses Spanish moss to build its nest. In addition to the number of warblers lost during the storm, there was a continuing loss afterward, probably because the moss needed for new nests was blown off the trees and scattered throughout the basin, making it difficult for the birds to find. This bird also uses the canopy of trees as a feeding ground, and lack of canopy for forage could also explain a decrease in the number of birds.

Other studies have shown some improvement of bird habitat in the Atchafalaya Basin. Birds that nest in tree cavities, for instance, did not lose their nests because the winds rarely completely toppled trees. The trunks remained standing, so the nest sites were not lost, even if a tree was heavily damaged. In fact, more nests were provided for cavity-nesting birds by the trees that were not toppled because new cavities were made when branches broke off.

While the number of resident birds dropped immediately after the storm, the broken forests provided some attraction for migrating birds like Neotropical warblers. These traveling songbirds visit the Louisiana forests on their migration through North America, but their new attraction to sites they usually ignored increased bird diversity in the basin right after the storm.

In Iberia, St. Martin, and St. Mary parishes, large areas of forest that provide important habitat for many species were affected by Hurricane Andrew. Scientists developed maps estimating damage to these forests and used a powerful computer tool known as a geographic information system to compare damaged areas with the known positions of bald eagle nests, colonial wading bird colonies, and the range of the Louisiana black bear. The analysis demonstrates the importance of maintaining multiple nesting sites and habitat for larger birds and mammals, though site or nest abandonment may result from other factors. (Figure 21)

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