Why You Should Visit
This is a great place to see prairie wildflowers, butterflies and grassland birds.
This preserve is a remnant of dry prairie that has managed to survive in a mostly agricultural landscape, probably because the limestone bedrock beneath the soil lies too close to the surface to permit cultivation.
Southwestern Wisconsin: 30 miles west of Madison in Dane and Iowa counties, in the "Driftless Area" — the only region in the state left untouched by the glaciers.
Open year-round, dawn to dusk (except during the winter when plowed snow prevents off-road parking)
There are no trails here, and poison ivy is abundant — so be careful!
Why the Conservancy Selected this Site
Thomson is a remnant of the past. Prior to settlement, many hilltops and steep slopes in this part of the state were covered with dry prairie vegetation. Today, this is one of the few remaining dry prairies in the state.
In addition, the prairie is home to a diverse natural community: More than 68 species of plants grow here, and 34 species of birds nest or feed here.
What the Conservancy Has Done/Is Doing
Little remains of Wisconsin's once extensive grasslands. Those that have managed to survive, like Thomson Memorial Prairie, are small, isolated and fragmented. To recreate a larger grassland ecosystem, these prairie remnants must be carefully managed and expanded.
The Conservancy owns and manages 704 acres at Thomson Memorial Prairie. With the help of volunteers, we are working to restore the degraded prairie and agricultural land surrounding the preserve through a combination of planting, prescribed burning and exotic species control.
How This Site was Named
The Conservancy named the area Thomson Memorial Prairie in recognition of John and Olive Thomson, longtime friends and stewards of the prairie. In honor of their deceased son Douglas, the Thomsons established a fund for land acquisition at the prairie.
What to See: Plants
Rare plants, such as pomme de prairie and green milkweed, thrive among a profusion of other prairie grasses and wildflowers. Many prairie plants grace this undulating landscape, including the following:
- Big bluestem
- Birdfoot violet
- Pasque flower
- Porcupine grass
- Yellow-star grass
What to See: Birds
The following species have been seen here:
- Aphrodite fritillary
- Tiger swallowtails
- Various species of skippers and sulphurs
Please see our Preserve Visitation Guidelines page for more information.
Note that hunting for white-tailed deer, wild turkey, and pheasant is allowed at Thomson Memorial Prairie during the regular posted seasons, with no prior permission from the Conservancy required. Dogs are allowed on the preserve but must be on leash from April 1 to July 31 to protect ground-nesting birds. When dogs are off-leash, they must be kept under voice control by their owners at all times to prevent them from creating a nuisance on adjacent properties and residences. Click here to go to the DNR's hunting season date website.
From the town of Mt. Horeb:
- Take US Hwy 18/151 west.
- Proceed to the intersection with Cnty Hwy F on the southwestern edge of Blue Mounds.
- Turn south on Cnty F and continue for just over one mile.
- At the intersection with Cnty Hwy Z, turn right — this will keep you on Cnty F.
- The preserve will be on your right in about one-half mile.
- Park in the small fenced parking lot or along side of the road.
All of our preserve maps are now georeferenced. You can download the free PDF Maps app on your Apple or Android device, and it will allow you to view your location, record GPS tracks, add placemarks and find places.