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
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
There is currently
an estimated
population in
excess of 1.5
million feral hogs
in 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
Origin:
South America
Fur ranchers imported nutria into California,
Washington, Oregon, Michigan, New Mexico,
Louisiana, Ohio, and Utah between 1899 and 1940.
Ecological Impact:
Destruction of native wetland habitat.
Nutria have been
reported in at least
40 states and three
Canadian provinces
in North America
since their
introduction.
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
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
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.
Mounds can be
hundreds of thousand
individuals
Photographer: USDA APHIS PPQ Archive
Source: USDA APHIS PPQ
Tawny Crazy Ant
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.
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.
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.
Muscovy’s 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
Origin:
Southern Russia
The Zebra mussel was first observed in North
America in 1988 in Lake St. Clair.
One zebra mussel
can produce 30,000
to a million offspring in
just one year.
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:
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.
Photographer: Amy Benson
Source: U.S. Geological Survey
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
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:
Asian tiger prawn are
aggressive and can
reach up to a foot in
length and one
pound in weight.
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
Origin:
Eastern Asia from the Amur River of
eastern Russia and China.
Introduced in the U.S. in 1963 for pond
and lake maintenance.
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
Grass Carp can reach
lengths of 4’5” and 88
lbs.
Apple Snails
Orgin:
https://www.youtube.com/watch?v=Pi2wcFPPJsI
South America
Introduce by the aquarium trade.
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:
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.
Photographer: Jess Van Dyke
Source: Snail Busters, LLC
Quilted Melania
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.
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.
Parthenogenic
species.
www.texasinvasives.org
www.nature.org
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
http://www.aphis.usda.gov/wildlife_damage/downloads/nepa/2014_Marsh_%20Restoration_and_Nutria_Damage_Reduction_EA.pdf
Chaniotis, BR, Butler, JM, Ferguson, FF, and WR Jobin. 1980. Bionomics of Tarebia granifera (Gastropoda: Thiaridae) in Puerto Rico, an
Asiatic vector of Paragonimiasis westermani. Carib J Sci. 16(1-4).
Abbott, RT. 1952. 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.71-116).
Online Sources:
http://el.erdc.usace.army.mil
http://nas.er.usgs.gov
http://fl.biology.usgs.gov
http://www.invasive.org