How mice with radios are helping restore Rollins Savanna near Grayslake

Well off the main trail, amid the milkweed and goldenrod in a farm field turned savanna, researchers hope some tiny mice with huge back feet can make a difference in the landscape.

“Like a little kangaroo,” Allison Sacerdote-Velat, reintroduction biologist with the Lincoln Park Zoo, said of Bubba, one of the meadow jumping mice released Monday at Rollins Savanna Forest Preserve near Grayslake.

With man-made barriers making it unlikely the tiny creatures could make it here on their own, raising them off-site and releasing them into the wild is a way to enhance the restored native environment.

Though she may never see some of them again, Sacerdote-Velat named the nine elusive rodents — all males — raised in captivity at the zoo specifically for this cooperative program with the Lake County Forest Preserve District. And it was more than just a sentimental lark.

“It makes telemetry more interesting for us,” she said.

The mice are fitted with tiny radio transmitters and their movements can be tracked and calculated. How far and to what location within the preserve they move, for example, is part of the information scientists will use to determine survival rates and the best places to boost their numbers.

“Part of this is to try to learn what works best in releasing these guys,” Sacerdote-Velat said. “This is our best site, so we know habitat quality can support populations of them.”

As part of its regular monitoring of wildlife populations, the forest preserve district determined that meadow jumping mice were rare or nonexistent at many preserves that had suitable habitats, explained Tim Preuss, a wildlife biologist with the district.

A partnership was forged with Lincoln Park Zoo to assess the status of this species and restore them to places they could call home. A first batch of mice was released at Rollins several weeks ago in the second year of a three-year program.

“Restoring the wildlife and diversity is a goal of the forest preserve district,” Preuss said.

Scientists say the amount of grassland has declined greatly over the years as areas were converted to farms or otherwise developed. While the forest preserve district has been acquiring and restoring these habitats, many species of wildlife have been unable to cross roads or traverse residential and commercial developments to get there.

The 1,200-acre Rollins Savanna was mostly farm land that has been restored by the district in the past 15 years. A savanna consists mainly of grassland and wetlands with some trees.

Essentially, the introduction of species like meadow jumping mice adds to the natural mosaic of restored properties.

They are about half to three-quarters the size of other mouse species but can jump up to 4 feet through grasses to elude predators. You're not likely to find them in your garage.

“To perpetuate native seed communities you need native seed dispersers,” according to Sacerdote-Velat.

“They're also prey for predators,” such as barn owls, she said.

On Monday, the mice were introduced to their new homes in two ways: a soft release in which five of the mice were put in individual pens covered with window screen mesh and chicken wire for protection and given wild bird seed, water and bedding material, and, the “let 'em loose” method or hard release.

The protected mice will be given three days to acclimate and then be released into the wild. All will be tracked daily for as long as the transmitters send signals.

“We're trying to learn more about how captive mice behave when they're released into the environment,” Sacerdote-Velat said.

Five litters of meadow jumping mice have been raised at the zoo, but there are only a few females. Since they are proven breeders, none were released Monday, Sacerdote-Velat said. And the others?

“We're hoping they all do well and thrive and find lady mice and keep the population going,” she said.