Invasive and Nuisance Fauna
of Texas Kelly D. Norrid Wildlife Biologist, Houston Urban Wildlife Program An "invasive species" is a plant or animal that is non-native (or alien) to an ecosystem, and whose introduction is likely to cause economic, human health, or environmental damage in that ecosystem. Once established, it is extremely difficult to control their spread. - United States Environmental Protection Agency Feral hog There is currently an estimated population in excess of 1.5 million feral hogs in Texas. Origin: Early Spanish explorers probably were the first to introduce Feral Pigs in Texas over 300 years ago. In the 1930s, European wild hogs, "Russian boars," were first imported and introduced into Texas Ecological Impact: Their rooting habits disrupt vegetation and soil, and cause shifts in plant succession on the disturbed site. Feral pigs also compete with several species of wildlife for certain foods, especially mast. Destroy habitat Eat eggs if ground nesting birds Photographer: Billy Higginbotham Source: Texas AgriLife Extension Service Feral hog consuming wild turkey eggs (Trail camera photo by Dr. Brett Collier). Nutria Nutria have been reported in at least 40 states and three Canadian provinces in North America since their introduction. Origin: Fur ranchers imported nutria into California, Washington, Oregon, Michigan, New Mexico, Louisiana, Ohio, and Utah between 1899 and 1940. South America Ecological Impact: Destruction of native wetland habitat. Nutria feed on seedlings and saplings, and have consequently denuded hundreds of thousands of acres of marshlands and floodplains along the Gulf Coast. The estimated agricultural and other recourses damage by nutria would probably exceed $1 million annually. Nutria forage directly on the emergent vegetation and the vegetative root mat in a wetland, leaving a marsh pitted with digging sites and fragmented with deeply cut swimming canals. Photographer: John and Karen Hollingsworth Source: US Fish and Wildlife Service Red Imported Fire ant Mounds can be hundreds of thousands of individuals Origin: The red imported fire ant was introduced around the 1930's and has spread to infest more than 260 million acres of land in 9 southeastern states Photographer: USDA APHIS PPQ Archive Source: USDA APHIS PPQ Ecological Impact: RIFA displace native ants from their habitat including: Texas leaf-cutter ant Harvester ant (Texas Horned Lizard) Carpenter ant RIFA is responsible for the reduction in population numbers of all indigenous ants. Birds, especially those that are ground-nesters such as the Bobwhite Quail are vulnerable to the Red Imported Fire Ant. Tawny Crazy Ant Origin: South America The Rasberry crazy ant was first discovered near Houston, Texas in 2002 by Tom Rasberry. The earliest record of N. fulva presence in the US is from Brownsville, Texas, in 1938 Now occupies 27 counties. There can be millions of pupae within any one colony of Rasberry crazy ants. Sometimes colonies are so large that the individuals are indistinguishable from those of neighboring colonies and a "super colony" may result with tremendous numbers. Ecological Impact: Nesting songbirds, are irritated by Rasberry crazy ants They rapidly colonize and take over various habitats, including human-built establishments They reportedly displaced all other ant species and caused small livestock (e.g. chickens) to die of asphyxia. Masses of crazy ants covering the ground and trees likely affect ground and tree-nesting birds and other small animals and cause wildlife to move out of the area. Photographer: Bastiaan Drees Source: Texas A&M University Muscovy Ducks Origin: South America and Mexico
Introduced to the U.S. around 100 years ago. Ecological Impact: Out compete native waterfowl (nesting in tree cavities). Interbreed with native ducks. Aggressive begging for food and mess created by droppings (about 150 g (1/3-pound) per day). They defecate in swimming pools and on patios and docks possibly causing health hazards. Large aggressive duck. Muscovys are not protected by state wildlife laws nor laws set forth by the federal Migratory Bird Treaty Act except for 3 counties in south Texas. Zebra Mussels One zebra mussel can produce 30,000 to a million offspring in just one year. Origin: Southern Russia The Zebra mussel was first observed in North America in 1988 in Lake St. Clair. Zebra mussels are currently in the following lakes: Texoma, Ray Roberts, Lewisville, Bridgeport, Lavon, Waco, Dean Gilbert and Belton. They have also been found in the Red River, the Elm Fork of the Trinity River, and Sister Grove Creek, and a boat with zebra mussels attached was found in Ray Hubbard. Ecological Impact: Photographer: Amy Benson Source: U.S. Geological Survey Zebra mussels have caused alarming declines in fish, birds, and native mussels by over-absorbing phytoplankton. Its high rate of filtration also leads to increased sunlight penetration, raising water temperatures and the depth at which that light penetrates the water. Known to spread between water bodies by hitching a ride on recreational watercraft such as motorboats and jet skis, as well as in bait buckets and other fishing equipment. Asian Tiger Prawn Asian tiger prawn are aggressive and can reach up to a foot in length and one pound in weight. Origin: Western Pacific The U.S. Geological Survey says they may have escaped from Caribbean aqua-culture farms, or from the water tanks of passing ships. Ecological Impact: Size could give tiger prawns a competitive advantage over smaller native shrimp when it comes to aquatic food resources. They feed on shrimp and crab, a fact which has alarmed many biologists who worry about native shrimp depletion. They are also thought to carry diseases that native shrimp may not have the immune system to fight. Houston Chronicle Asian Grass Carp Grass Carp can reach lengths of 45 and 88 lbs.
Origin: Eastern Asia from the Amur River of eastern Russia and China. Introduced in the U.S. in 1963 for pond and lake maintenance. Grass Carp can reach lengths of 45 and 88 lbs. Ecological Impact: Have the potential to cause enormous damage to native species because they feed mainly on plankton, a vital source of nutrition for larval fish and native mussels. Competitor with some native fish, like gizzard and threadfin shad, that depend on plankton for food. Commonly remove too much vegetation and deteriorate habitat for game fish. Can harm water quality by increasing phosphorus levels Apple Snails Orgin: https://www.youtube.com/watch?v=Pi2wcFPPJsI
South America Introduce by the aquarium trade. https://www.youtube.com/watch?v=Pi2wcFPPJsI Apple snails with channeled shells are now established in six counties in southeastern Texas. Island apple snails (P. insularum) Channeled apple snails (P. canaliculata). Ecological Impact: Photographer: Jess Van Dyke Source: Snail Busters, LLC It may be a vector for disease and parasites such as the lungworm (eosinophilic meningoencephalitis) in humans Snails also contribute to skin irritations by being intermediate hosts to the associated trematodes. Apple snails are a serious threat to wetlands by the potential destruction of native aquatic vegetation that causes serious habitat modification, as well as competition with native fauna, including native snails. Quilted Melania Parthenogenic species. Origin:
India east to the Philippines and Hawaii, north to South Japan and south to the Society Islands. Introduction date of 1940 has been suggested. Researchers believe the main method of introduction was via the aquarium industry. Parthenogenic species. Ecological Impact: Aggressive competitor with native species. Pose a health risk to humans and birds. By acting as an intermediate host to various trematodes that can infect humans as well as birds. U.S. Fish and Wildlife Service Texas Parks and Wildlife
Texas AgriLife U.S. Fish and Wildlife Service Texas Parks and Wildlife U.S. Department of Agriculture Animal and Plant Health Inspection Service Wildlife Services Chaniotis, BR, Butler, JM, Ferguson, FF, and WR Jobin Bionomics of Tarebia granifera (Gastropoda: Thiaridae) in Puerto Rico, an Asiatic vector of Paragonimiasis westermani. Carib J Sci. 16(1-4). Abbott, RT A study on an intermediate snail host (Thiara granifera) of the oriental lung fluke (Paragonimus). In: Proceedings of The United States National Museum. Vol 102(p ). Online Sources: