Cover Story . . .

Turtle Towers Being Installed at Thomson Prairie

West Carroll Middle School 4th graders take a field trip to study the Thomson prairie and the plight of the imperiled box turtles. (Courtesy of USFWS)

Recreational enthusiasts using the Thomson Bike Trail will soon be seeing some new additions to the prairie landscape. The U.S. Fish & Wildlife Service is installing 9 radio towers at the Thomson Sand Prairie to track ornate box turtles on the Upper Mississippi River National Wildlife and Fish Refuge. The turtles have small radio transmitters affixed to their shells. The radios send signals that are received by the antennas affixed to the 30 foot tall towers. Each tower’s computer will document the daily movement and activity of the turtles.

Wildlife Refuge Manager Ed Britton explained “The information being collected is part of a long term research study to identify management techniques that are needed for the conservation and protection of this imperiled species. The towers will collect hourly turtle movements. The continuous recording of turtle activity will increase our knowledge of turtle movements, a key factor in identifying management actions that are needed.”

The ornate box turtle was listed as a threatened species in Illinois in October 2009 due to its declining population status. Population decline was primarily attributed to the loss of sand prairies, an important habitat type used by the box turtles. Sand is required because ornates hibernate during the winter and must be able to bury themselves 2-3 feet underground. Box turtles are long lived individuals (30-40 years) that have a solitary life style. Males don’t mature until they are about 10 years old and females about 12 years old.

Radio telemetry studies on the ornate box turtle population at the Thomson Sand Prairie began in 2008. The Thomson Prairie contains 360 acres and is one of the largest sand prairies in Northwest Illinois. Ten turtles were initially tracked with hand held receivers. The turtles were tracked intermittently throughout the summer to document their habitat use areas, home ranges and hibernation dates. One turtle was killed by a predator, possibly a coyote.

The telemetry study was expanded in 2009 and included 28 radioed turtles located at two sites. There were 26 radioed turtles at the Thomson Sand Prairie and 2 at the Lost Mound Sand Prairie. Lost Mound contains 4,000 acres of sand prairie habitat and historically supported a box turtle population. However, decades of military operations at this former military installation (Savanna Army Depot) combined with overgrazing by cattle (to reduce the fire hazard) eliminated all but a few individuals.

In June 2009, a gravid female was captured at the Thomson Prairie. She was injected with a chemical (oxytocin) to induce egg laying and her 4 eggs were taken to the Niabi Zoo to begin a head-start program. Head-starting is the process of raising hatchlings in a protected environment until they are large enough to avoid predation. The predation of nests and hatchlings is a primary cause of mortality. The 4 head-started turtles will be released at Lost Mound in June 2010. The size and body weight (over 100 grams) of these 10 month old turtles will be equivalent to a 7-8 year old wild turtle. They will be affixed with radio transmitters and monitored for several years.

Some of the preliminary information that has been collected from 2008-2009 telemetry study shows: the average home range of a turtle within the historical population at Thomson was 7 acres whereas the 2 turtles that were rescued from areas of danger (highways/development) and released at Lost Mound had a home range of 361 acres and traveled up to two miles; a female hibernated for 7 months at a depth of 3 feet below ground and; ornates return to almost the exact location year after year to hibernate.

The study of ornate box turtles in 2010 is expanding to include 7 sand prairies in Northwest Illinois. These include 5 prairies within the Upper Miss Refuge and 2 in the Illinois Nature Preserves System. Hopefully, ornate box turtles will be found at each of these prairies. Four of these prairies are small and isolated being surrounded by development or agriculture. Miniature temperature data loggers are being affixed to a few turtles to monitor activity related to temperature.

This research project has developed a strong partnership between local conservationists, colleges, developers, and state and federal agencies. The Jo Daviess Conservation Foundation, Lost Mound Corps of Discovery, Iowa State University, Jo-Carroll Depot Redevelopment Authority, Illinois Department of Natural Resources and the Fish and Wildlife Service are working together to make this project successful. There are also many individuals, volunteers and college students contributing to this project.

The U.S. Fish and Wildlife Service is the principal federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 95 million acre National Wildlife Refuge System which encompasses 545 national wildlife refuges, thousands of small wetlands and other special management areas.