Invasive Species

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Also known as exotic or non-native, invasive species pose a big problem due to displacement of native plants and animals. The majority of invasive species occur due to human activity either purposefully or accidental.


Non-native Plant Species
 
There are several invasive species present on the refuge, with the Chinese tallow tree being the most prevalent. In Louisiana, old fields and pastures that once provided grassland bird habitat are replaced with forests of the exotic Chinese tallow.

Tallow trees typically grow on elevated and undisturbed ground along fence rows and levees. Refuge staff have worked to eliminate Chinese tallow from some levees and to replant with native species. Chinese tallow control is a major management concern for the refuge, with prescribed burning and herbicides used to control it. However, this exotic is a very resilient species and tends to re-sprout after the herbicide is applied. Its ability to regrow from the roots left behind also restricts the usefulness of fire as a control measure.

Other non-native, including non-invasive, species are water hyacinth, water lettuce, common salvinia, hydrilla, alligator weed, bamboo, Chinaberry, St. Augustine grass, Bermuda grass, and lantana.

Non-native Animal Species

One of the most invasive animals on the refuge is nutria. The nutria is an exotic herbivore that can cause significant damage to marsh habitats when populations become elevated, an event referred to as eat-outs. Currently, nutria populations throughout the refuge and in the general area are relatively low, causing minimal damage to habitats requiring a minimum of population control. Change in vegetative communities outside of Lacassine Pool may occur again in future years. With favorable habitat conditions and the nutria's high reproductive potential, the population can expand rapidly. Although nutria can be destructive to levees and vegetation, the species is beneficial in that it is available as a food source for alligators, coyotes, and bobcats. Another prevalent invasive mammal is the feral hog.

No exotic reptiles and amphibians are known to occur on Lacassine Refuge, but a few are established in nearby parishes and others are expanding their range out of Florida. Of special concern is the brown anole (Anolis sagrei) that displaces the native green anoles (Anolis carolinensis). Efforts are made to monitor reptile and amphibian populations; however, little may be done to stop species, such as the brown anole, once established.

 The domestic cat has established wild, free-roaming populations throughout most of the United States. Feral cats can be devastating to native birds, but they also prey very heavily on other native wildlife, such as snakes, lizards, and rabbits. What effect feral cats have on the refuge's wildlife population is unknown. 

The Eurasian collared dove occurs on the refuge, but apparently is harmless to other species.