Invading lizards caught in jam at Indiana park

Marmeladefallen gegen eindringene Eidechsen in einem Park des Bundesstaates Indiana, USA

Übersetzung und Bearbeitung: Dr. Ingo Kober, DGHT
Redaktion: Dr. Guntram Deichsel

Foto: Robert Seipp

Mehrere europäische Lacertiden-Arten haben in den letzten Jahrzehnten an verschiedenen Orten in den USA reproduzierende Populationen ausgebildet. Dabei handelt es sich in der Regel um entkommene, häufiger aber wohl ausgesetzte, Terrarientiere. Ein neuer Fall wurde jetzt aus dem Falls of the Ohio State Park, einer bekannten Fossilienfundstätte bei Clarksville, Indiana gemeldet. Nach einer ersten Sichtung im vorletzten Sommer haben sich dort Mauereidechsen (Podarcis muralis) offenbar bereits merklich vermehrt. Die Tiere entstammen wahrscheinlich einer Population in Cincinnati, wo sich die Art bereits seit etwa 50 Jahren erfolgreich fortpflanzt. Im Stadtbereich leben inzwischen Tausende dieser Eidechsen. Dort gibt es keine signifikanten Vorkommen heimischer Reptilien, die durch die Neuankömmlinge bedroht wären und daher ließ man die Fremdlinge in Cincinnati bisher in Ruhe. Ihr kürzliches Vordringen in den Falls of the Ohio State Park, den sie möglicherweise als blinde Passagiere auf Treibholz erreichten, muss dagegen als bedenklicher angesehen werden. Herpetologen befürchten, dass die vermehrungsfreudigen und agressiven Europäer heimische Reptilien aus ihren Lebensräumen verdrängen könnten, wenn ihrer Vermehrung nicht Einhalt geboten wird. Daher hat Zachary Walker, Herpetologe des Department of Natural Resources damit begonnen, Fallen zu entwickeln, um die fremdländischen Echsen gezielt weg zu fangen. Derzeit werden diese Fallen mit Erdbeermarmelade beködert und häufig kontrolliert. Bisher konnten aber erst fünf Mauereidechsen auf diese Weise eingefangen werden. Darunter befand sich auch ein Jungtier, dessen Fang als deutlicher Hinweis zu werten ist, dass die Art sich inzwischen im Park auch schon erfolgreich fortpflanzt. Die Naturschützer des Parkes, die außer mit den Mauereidechsen auch mit weiteren, sich agressiv verbreitenden, fremdländischen Arten aus Tier- und Pflanzenwelt zu kämpfen haben, hoffen, der Eidechsen noch rechtzeitig Herr zu werden, bevor sie sich unwiderruflich im Park etablieren. (Quelle: The Courier-Journal)

Besonderer Hinweis: Bei den Mauereidechsen (Podarcis muralis) aus Cincinnati, Ohio und dem Falls of the Ohio State Park bei Clarksville, Indiana, handelt es sich um die Unterart P. m. maculiventris
(Southern Alps lineage).
SCHWEIGER S. & G. DEICHSEL 2003: Podarcis muralis. Herp. Rev. 34(2)166-167 (Genotypisierung der Cincinnati- Mauereidechsen)
WALKER Z. & G. DEICHSEL 2005: Podarcis muralis. Herp. Rev. 36(2): 202 (Genotypisierung der Indiana-Mauereidechsen)
DEICHSEL G. & Z. WALKER 2010: Podarcis muralis, Control.  Herp. Rev. 41(2): 228-229 (Ausrottungsprogramm der Indiana-Mauereidechsen)


Nachfolgend die Originalfassung des Artikels

Manuscript, published in
wpe21.jpg (17538 Byte)
July 08, 2005
Louisville, Kentucky

Invading lizards caught in jam at Indiana park

By LESLEY STEDMAN WEIDENBENER

Nick Burgmeier, with the Indiana Department of Natural Resources, replaced a trap at the Falls of the Ohio State Park yesterday. The traps have a glob of strawberry jam surrounded by a sticky substance. (By Michael Clevenger, The Courier-Journal) This wall lizard was caught at the state park in Clarksville yesterday. (By Michael Clevenger, The Courier-Journal)

A reptilian invader at the Falls of the Ohio State Park has Indiana officials laying traps baited with strawberry jam to try to protect native species.
An unknown number of European wall lizards have moved into the park along the Ohio River in Clarksville, probably after catching a ride on driftwood from Cincinnati, where a population was established more than 50 years ago.
The insect-eating lizards -- slender, sleek and up to 8 inches long -- can be seen sunning themselves on rocks and the park's concrete retaining wall or scampering through the flower gardens, said property manager Steve Knowles.
"We've not seen them out on the fossil beds" for which the park is known, Knowles said. "They like the riff-raff below the Interpretive Center."
The lizards are not dangerous to humans, but they may pose a threat to lizards that are common to the region.
Wall lizards "are more aggressive," said Christopher Pierce, an extension entomologist at Purdue University who oversees invasive species surveys for the state. "They could reproduce and compete better than the native species there. That's a concern."
A visitor was the first to spot a wall lizard at the park two summers ago and e-mailed the park's naturalist about it.
"We started looking it up," Knowles said. "We realized this is something different."
But officials didn't notice the species in significant numbers until last year, when the Division of Fish and Wildlife started developing a plan to control the population. By the time officials decided to try to trap the lizards, they had begun hibernating for winter, Knowles said.
So this year Department of Natural Resources herpetologist Zach Walker began testing traps, and a college intern was hired this week to set them daily, baited with jam, and check them every two hours. That ensures that native lizards can be released quickly and remain unharmed.
The wall lizards are euthanized.
State experts are unsure how many wall lizards are in the park, said Kacie Ehrenberger, a wildlife diversity staff specialist for the state. But so far, she said, none have been seen outside the park.
"We're trying to do this before they spread out," she said.
There are thousands of wall lizards in Cincinnati. They reportedly arrived in the early 1950s from northern Italy with a family who had been visiting Milan, according to the Ohio Department of Natural Resources. The family released the lizards in their back yard.
They multiplied and spread, living through the region's cold winters, which often kill off other non-native species of animals.
In Cincinnati the lizards now occupy an area slightly larger than two square miles, with population densities of 1,500 per acre in good habitat, the Ohio natural resources department reported.
Ohio has no program to try to control them, although a Xavier University biologist is studying their effect on the area.
Ehrenberger said the impact in Cincinnati may be of less concern because in an urban setting there are fewer native lizards to displace. But the presence of the lizards in an Indiana state park is different, she said, because it is a more natural setting.
Non-native species are of particular concern to wildlife specialists.
In the absence of natural predators, parasites and competitors from their native habitat, exotic species can overrun native species, according to the natural resources department. Once established, exotic species are difficult to eradicate.
Indiana officials can't be sure how the wall lizards arrived in Indiana. They believe it's likely they rode driftwood from Cincinnati downriver to the Falls of the Ohio during a flood.
But Knowles said they could have also arrived just as they got started in Cincinnati -- because someone had them as a pet or picked them up elsewhere, brought them to the area and then released them at the park.
"This is a growing problem across the country," Knowles said. "Our world is shrinking globally, and we're having more world travelers who find things they want to keep at their house in a cage as a pet. But we're not repositories for people's cast-off exotic pets."
The problem is not unique to lizards, although Pierce said the wall lizard is the first invasive reptile to come to Indiana.
The state is struggling to deal with several invasive aquatic species -- both fish and plants. Eurasian milfoil is an aquatic weed that Pierce said someone probably had in an aquarium and then decided to throw in a lake.
The natural resources department has spent thousands of dollars to try to eradicate the plant, which grows earlier and more quickly than native species and blocks the sun so other aquatic life can't thrive.
The state is also working on an educational campaign about the Giant African Land Snail, which has been illegally traded at pet shows and then released, Pierce said. They can reproduce quickly and can spread disease to humans.
Pierce said he is tracking about 20 different invasive plants, animals, and insects that have become established in Indiana and are now threatening native species.
Wall lizards -- which have also been found in parts of Canada and in Long Island -- are only the newest inhabitant.
So far the traps at the Falls of the Ohio have caught five wall lizards, including a tiny one Thursday that led Knowles to believe the species is reproducing there. Yesterday a trap caught one about 6 inches long.
"I'm happy we're doing this because it's important," Knowles said. "We want native populations to flourish."

© The Courier-Journal

Note: The subspecies of the Cincinnati and satellites Wall Lizards was meanwhile revised as Podarcis muralis maculiventris (Southern Alps lineage)
SCHWEIGER S. & G. DEICHSEL 2003: Podarcis muralis. Herp. Rev. 34(2)166-167
WALKER Z. & G. DEICHSEL 2005: Podarcis muralis. Herp. Rev. Rev. 36(2): 202
DEICHSEL G. & Z. WALKER 2010: Podarcis muralis, Control.  Herp. Rev. 41(2): 228-229


Guntram Deichsel, Novemver 2012:

Alan Goldstein vom Falls of the Ohio State Park in Clarksville, Indiana, berichtet in einer E-Mail an G.D., dass bis zum Herbst 2012 keine Mauereidechsen mehr im Park gesichtet wurden. Demnach erwies sich das Ausrottungsprogramm als erfolgreich.

Alan Goldstein of the Falls of the Ohio State Park in Clarksville IN reports in an email to G.D. that as by fall 2012 Wall Lizards have no longer been seen in the park. Hence the eradication program turned out to be successful.