Squirrels: There’s No Place Like Home

Data is collected on vegetation type and height in ground squirrel habitat.

We are moving California ground squirrels from one location to another (tranlocating) to test if their presence can help restore grassland habitat and provide natural burrow homes for western burrowing owls. Currently, management of burrowing owl populations requires a lot of human intervention; artificial burrows are built in hope that owls will come and use them. However, there hasn’t really been enough focus on this issue from a grassland ecosystem restoration standpoint.

A transect begins to search for California ground squirrel burrows.

In areas where ground squirrels are relatively common, lots of native plants and other animal inhabitants benefit. Ground squirrels serve as “ecosystem engineers,” building intricate burrow systems, clearing large amounts of vegetation, and serving as anti-predator sentinels for some species. They also play the role of dinner, too!

An old California ground squirrel burrow we found was actively being used by a pair of burrowing owls. Note the “white wash” (bird droppings) at the entrance.

But what determines where a ground squirrel likes to live? Sometimes it seems like they are everywhere: in parks, at the beach, alongside roads, and around our properties. But when it comes to grassland habitats in San Diego County, they’re not always present where you might initially expect them to be. Figuring out where ground squirrels can and prefer to live is especially important when you want to move them to places where they are going to be successful. After all, we want them to establish a new population in a place that will allow them to help the habitat as a whole.

One exciting thing I’ve been working on over the last few months is collecting data for the California ground squirrel habitat suitability model in order to determine what habitat variables predict the presence or absence of ground squirrels in a particular area. The idea is that the more we know about what makes excellent ground squirrel grassland habitat, the higher our chances of success will be when translocating them to a new environment that is in need of some “natural” restoration.

At study sites around the county, we’ve been surveying for ground squirrel burrows and collecting data on the surrounding habitat characteristics, vegetation type, and height in the area and any potential burrow protection observed. We have also noted if we’ve seen squirrel predators in the area, like coyotes or red-tailed hawks. In addition, we’ve also been taking soil cores to determine soil density and other attributes, which we’ll assess later in the lab. Because ground squirrels are fossorial, we think soil type has a huge influence on their habitat preferences. I’m eager to process the samples and see the results after all the dirty work of collecting them. Working with soil has turned me into the filthiest-looking researcher in the building. I’ll be happy to know that all of those extra loads of laundry I’ve had to do have paid off!

Susanne Marczak is a research technician with the San Diego Zoo Institute for Conservation Research. Read her previous post, A New Nature.

2 Responses to Squirrels: There’s No Place Like Home

  1. My wife and I have a 1/4 acre that we have “re-vegetated” with native plant life. How can we entice squirrels to move in?

  2. Hi Ken!

    That’s wonderful that you have taken the opportunity to use native plants to re-vegetate your property and that you want to encourage the presence of local wildlife. Providing cover such as brush piles or logs creates places that squirrels can use for shelter from predators such as coyotes and raptors. If there are squirrels near your property, that could be a good way to encourage them to move in. When trapping ground squirrels this spring and summer, we found that they absolutely LOVE black oil sunflower seeds, so sprinkling some around might help as well (they can be purchased at your local feed shop). It is likely to also bring some more local birds to your property as well! Just a reminder that trapping squirrels and moving them to your property would be illegal, so these natural enticements are a great choice. Good luck with creating the “native paradise” in your own backyard! :-)