Southern Idaho Ground Squirrels Get Some Help To Survive

May 3, 2013

Zoo Boise isn’t just a place to go to look at animals.  It also helps animals in the wild. The zoo donates money to several conservation projects around the world.  One of those projects is right in our backyard, near Horseshoe Bend.  The zoo, and a scientist from the College of Idaho, are trying to save a small ground squirrel that's struggling to survive.

A crew of eager volunteers dig trenches in the desert east of Horseshoe Bend.  They put four by eight foot wire mesh pens in the ground, making sure the sides are buried deep.

Dr. Eric Yensen is a professor of biology at the College of Idaho.  He’s working with Zoo Boise to establish a colony of southern Idaho ground squirrels on this parcel of public land.  There are 10 species of ground squirrels in Idaho.  This one is in trouble.   Estimates vary, but scientists think there are 4,000 left. “They only occur in Idaho and they only occur in Gem, Payette, and Washington counties.  Period.  That’s their entire range in the whole world,” explains Yensen.

Southern Idaho Ground Squirrel
Credit Samantha Wright / Boise State Public Radio

The southern Idaho ground squirrel is small, sort of a brownish dirt color, with a short, ropey tail.  They’re losing habitat to people.  They like the rich bottomland soil, the same soil farmers like. 

The squirrels face another invader: cheatgrass.  The plant crowds out the native vegetation, which the squirrels need to survive.  Zoo Boise Executive Director Steve Burns says they face a host of threats.  Burns and Yensen tick them off, starting with the badger. “Badgers are unbelievable, efficient ground squirrel eating machines,” says Burns.  Yensen adds, “And then you’ve got the weasels and the coyotes and the foxes and then you’ve got the rattlesnakes and the gopher snakes.  Then up above you’ve got the prairie falcon, then there’s the red-tailed hawk, the Swainson's hawk, the rough-legged hawk, the northern harrier, Cooper's hawks, and ravens.”

Yensen says human hunters also affect squirrel numbers.

Past attempts to form new colonies of the animals didn’t go well.  That’s because most of those were a “hard release.”  That’s when you pop open up the box of squirrels at the release site and they start running. “And they’re panicked, they don’t have their burrows, they don’t have their places to hide from predators, they just panic and run and pretty soon they get eaten and that’s that.”

For this three-year project, Yensen’s trying a soft release of animals bred at Zoo Boise and trapped from ranches and golf courses in the area.  That’s where the wire mesh pens come in.  The squirrels are released into a protected cage, complete with a nest box to hide in.  “As soon as they see the opening, they’ll dive down and go into the nest burrow, the nest box that we have there.  That’s where they’ll live until they leave the pen.”

They get fed once a day.  Burns says any predators, like badgers or foxes, are relocated away from the site.  “We sort of help the ground squirrels along for a period of time, help them get their bearings, get established, feel at home, and then they would start to survive on their own.”

For three months, people watch out for the squirrels as they dig under their release cages and start forming their own colony of burrows.  This time of year, they dig, and they eat.  They have to get fat because, like bears, they spend much of their life hibernating underground.   But unlike bears, ground squirrels do it to survive the hot dry summer and fall. “The desert dries out and when it dries out there’s nothing for them to eat.  So from mid-to-late June they go underground and they stay underground until January.”

Wire mesh pens are set into the ground along the desert landscape
Credit Samantha Wright / Boise State Public Radio

Volunteers will watch over the squirrels until they go to sleep.  Then they’re on their own in their new habitat. 

Yensen says last year’s release, the first in the three-year project, went well.  Around 30 of the 100 squirrels released survived.  That may not sound like a lot, but Yensen says it’s a positive sign for a species that’s a candidate for listing under the Endangered Species Act. 

Professor Eric Yensen and zoo director Steve Burns hope this project will re-establish more of the species. “It is endemic to the state of Idaho,” says Burns.  “So if it’s gone from here, it’s gone forever, it’s gone from the planet and what a tragedy that would be.  Clearly this is something that is unique to Idaho and we should have it here.”

The $100,000 project is funded by Zoo Boise’s conservation program.  Burns says the project has two goals: to put more squirrels back in the wild and to develop a successful technique for trans-locating ground squirrels, in case they are put on the endangered species list.

You can find out more about the southern Idaho ground squirrel trans-location project this weekend at Zoo Boise.  The zoo is hosting a Wildlife Conservation Expo, to celebrate raising $1 million for conservation projects. 

Copyright 2013 Boise State Public Radio