I spent the week in Minneapolis, Minnesota! I attended the International Society for Behavioral Ecology Conference, a meeting where animal scientists 🦁🐝🐍🤓from around the world 🌎meet to share their research 🔬⚗📈.
In honor of my trip ✈️, today’s Sunday Squirrel Spotlight star 🐿🌟 is the thirteen-lined ground squirrel (Spermophilus iridecemlineatus)! These squirrels are abundant in Minnesota and can be found on grasslands and prairies 🌾.
Thirteen-lined ground squirrels have quite a few nicknames, including the striped gopher and the leopard ground squirrel. These elaborately decorated cuties live solitary lives in burrows deep underground that they also use for food storage and hibernation. These sneaky squirrels have also been observed creating “emergency burrows”, or shallow holes in the ground that can be used to make quick escapes from snakes 🐍and falcons 🐦.
Thirteen-lined ground squirrels are tasty snacks 🍗🍕 for birds of prey like owls, as well as coyotes and snakes. When they are above ground foraging it is important for individuals to be able to accurately read signals from the environment , because potential danger may be lurking 👀.
To keep safe these striped squirrels have two primary strategies. First, they tend to forage close to burrow entrances. This allows them to make quick escapes if a predator shows up. Second, thirteen-lined ground squirrels will visually scan their environment looking for predators 🐍👀.
One study found that these squirrels preferred not to forage further than 2 meters (6 feet) from a burrow entrance, and the presence of a plastic owl in the area resulted in squirrels foraging less and hiding more.
Thirteen-lined ground squirrels are solitary and do not always warn others when they detect predators. Mother squirrels however, have been found to sound the alarm by calling to their foraging babies. These same squirrels will not call if their litter is not out foraging and single males and non-breeding females tend to alarm call less.
Here is a short video demonstrating this alarm calling behavior!
Cleary & Craven, 1994; Thorson et. al., 1998; Schwagmeyer, 1980
The first step to squirrel gazing 🐿👀 is attracting squirrels!
This is usually done by handing out snacks to these furry foragers. 🌰
But, what should you be filling your feeders with?
To find out what wild squirrels like to eat 🍕🍪🍿 I went to my local grocery store and purchased a sampler of every type of nut and seed they had! (This does get you some weird looks at the checkout stand! 💁🏻👀)
Next, I counted out 40 of each food type, mixed them all together, and placed them on a tray. It’s like a squirrel Hometown Buffet.
Let the food preference test begin!
Everyday for six days, at 5pm I would place the tray at the base of the favorite tree of my loyal crew of 12 fox squirrels 🐿in the botanical garden 🌻🌲 on the UCLA 🐻 campus .
The tray would remain in the garden for two hours. At the end of which I recorded how many pieces of each food type was left behind. 🌰
The results are in! 🔎 📊
The favorite food of the UCLA botanical garden fox squirrels (Sciurus niger) are Walnuts! Followed closely by a tie between peanuts and hazelnuts.
Close to 80% of all the walnuts placed on the food tray over the six testing days were chosen by the squirrels. Compare that to the least liked food, sunflower seeds 🌻, where only about 10% of the items were taken!
The information I gained by completing this food preference test will help inform what types of squirrel snacks I should fill my data collecting feeder with!
Here is a video montage of squirrels selecting their favorite foods! 🐿👀🎥
Today’s Sunday Squirrel Spot Light star 🐿🌟is the Southern flying squirrel (Glaucomys volans). These squirrels glide through the air using a specialized skin membrane that stretches from ankle to ankle called a patagium. This allows them to leap from branches and gracefully glide through the sky to other nearby trees or down to the ground forage.
Southern flying squirrels are found in Eastern North America, but are rarely seen by squirrel gazers 🐿👀because unlike the other squirrel species profiled so far, southern flying squirrels are nocturnal🌙🌲. Using their extra large eyes, these flying rodents are able to see and forage at night. Flying squirrels enjoy eating insects, bird eggs, and fruits, but their favorite meals are hickory nuts and acorns 🌰. They do not hibernate during the winter months when food is hard to find, so they have to store food for later!
Southern flying squirrels are social animals and live in groups tucked inside hollowed out tree cavities, and sometimes occupy abandoned woodpecker holes. To communicate with their buddies these squirrels use ultrasonic vocalizations! Ultrasonic vocalizations are sounds so high pitched humans can not hear them. These are the same type of sounds that bats use for echolocation!
I have never been lucky enough to see a Southern Flying Squirrel myself so, today’s video clip is from National Geographic's coverage of research being done on squirrel flight mechanics. Watch these tiny flying rodents glide over a football field 🏈with ease!
(Neilson, 1918); (Thomas & Weigl, 1998); (Garroway, Bowman, & Wilson, 2013); (Marrant, et. al., 2013)
What is more adorable than a California ground squirrel?
A baby California ground squirrel!
Most California ground squirrel populations breed only once a year in the springtime, right around the time they emerge from their burrows after hibernating through the cold winter months.
Excitingly, in warmer places like Southern California these squirrels tend not to hibernate and have been found to breed all year long! This is great news for Squirrel Gazer because there are a ton of cute baby squirrels running around the James Reserve where our research is being conducted!
Grace is one of the resident ground squirrel mothers on the reserve. She can often be seen watching her 3 young pups foraging from the comfort of her burrow entrance.
California ground squirrels moms are pregnant for about one month. Females will give birth to a litter consisting of an average 5 pups. After about 5 weeks living exclusively in their burrow, these tiny cheeky squirrels will emerge to explore the world above ground.
Ground squirrels like Grace are notoriously good mothers. Rattlesnakes find squirrels to be a tasty snack and ground squirrel mothers will take big risks to protect their offspring from becoming lunch. Female ground squirrels with vulnerable offspring are more likely than other adult squirrels to participate in “anti-snake behavior”. This behavior includes wagging their tail in the air (tail flagging) to help them appear larger and harassing the snake by approaching it and kicking dirt towards it. This is an overly simplified description of a very cool and complex behavior for which there is a large body of scientific literature on. I will discuss in more detail in a future Ground Squirrel vs. Rattlesnake blog post!
We do not microchip youngsters for our study to prevent unnecessary stress to them or their mothers, but that does not stop these mischievous little scurides from setting off the body heat sensors in the feeder and enjoying an afternoon snack! We don’t mind though...it makes for great squirrel snack footage!
(Evans & Holdenried, 1943); (Grinnell, 1918); (Swaisgood, Rowe, & Owings, 2003)