It may have taken humans a long time to discover the benefits of reusable grocery bags, but California ground squirrels have known them for a long time. Cheek pouches are the ultimate reusable bag conveniently and permanently attached to a ground squirrel's body and a lot of other mammal species for that matter (fun fact: platypuses have cheek pouches!).
Cheek pouches allow these squirrels to collect more food while foraging than would be possible to eat or carry at one time. Without the limitation of only being able to carry what could fit in their mouths, ground squirrels can load up on food and take it to a safe location to eat or store.
There is a common misunderstanding that animals with cheek pouches are storing their bounty inside their mouths. In fact, a cheek pouch is a pocket like skin tube located between the cheek and the jaw. The opening of the pouch begins at the mouth and can sometimes almost span the length of an animals entire body!
Specialized muscles help the animals empty their cheek pouches when they are ready to relocate their newly collected food. If you have a few hours to fall down a YouTube rabbit hole, I defiantly suggest watching videos of and animals emptying their cheek pouches. It is so cool!
Last week at the James Reserve I set out to find California ground squirrels' favorite food 🌰🌻🍕. Understanding what types of nuts and seeds they prefer will help me decide what to use in my automated feeder when my decision making experiment begins 🔎.
To do this I placed out a tray of 5 different nuts and seed choices and counted which the squirrels took the most. To learn more about the food preference test I use, take a look at my blog post from August.
When running these tests I set up motion sensing cameras 🎥 around the tray to ensure it is in fact squirrels taking the food. This led to an up close and personal view of California ground squirrels filling their cheek pouches with goodies! Be sure to check out the slow motion footage below!
A top priority for many tree squirrels 🌲🐿like this Eastern grey squirrel (Sciurus carolinensis) is the storing of thousands of nuts during the spring and summer, in order to survive through the winter.
Eastern grey squirrels, like many other of their arboreal relatives 🌲🌳, are scatter-hoarders. This means that they hide each nut 🌰 they find in a different location as opposed to storing all the food in a single place like a burrow.
Storing each food item in a separate location presents some serious security concerns 👮🚓. Thievery is rampant in the squirrel world! Bury a nut and a sneaky fluffy tailed intruder may come in and take it while you are away 👀🌰🐿.
Scatter-hoarders cannot defend each of their individually stored items from theft. So, instead they have developed unique anti-theft strategies to keep their hoard safe.
1.) The Take and Travel- One way to cut down on the risk your buried nut will be stolen, also referred to as pilfered, is to take your food item and travel ✈️🚗🚀as far as possible from the place you found it prior to burrying it underground.
Why? The mainstay of an arboreal squirrel's diet are tree nuts which are primarily found at the bottom of trees. So the logic follows; if there is one nut at the bottom of a tree 🌰🌲, there is likely more nuts there 🌰🌰🌰, and nuts attract squirrels 🐿💕🌰. So, if you burry your nuts around where you found it there will be more squirrels in that area that may find your hidden stash and take it for themselves! 🐿🐿🐿
2.) The Risky Run- For the braver squirrels out there another anti-theft strategy is to store your items in dangerous locations 😼🐍. For example, take your nut to a backyard that is known to have a few pesky dogs roaming around in it 🐶🐶.
Why? If you store your food in an area that few squirrels are courageous enough to search your chances of being able to pull up that nut 🌰a few months from now is greatly increased. The downside to this strategy is that you may have to put yourself in harms way to burry your food in risky locations.
I once saw a squirrel run across a busy street and burry a nut inside a small planter right outside the door to a busy Starbucks ☕️. More than likely that nut will not be stolen, but he will have to avoid traffic 🚗🚕🚙to get back to it in the future!
3.) The Fake-out- Lastly, if you find the perfect location to burry your newly found nut 🌟🌰, but you notice another squirrel is watching you 🐿👀you can always opt for the fake-out, also known as 'false caching'.
When a squirrel notices other squirrels 🐿or even sometimes birds 🐦 or humans 😳watching them bury food, they will pretend to bury it and secretly carry the item to a different storage location! When utilizing the fake-out strategy squirrels will go through the entire nut burying process, even taking the time to camouflage the fake cache with leaves 🍁and sticks just like they would if they were storing a real food item.
Why? If you are being followed by a thief, pretending to bury a food item may distract them allowing you to carry your nut to a more discrete location. While they hurry over to steal your new cache you can run off in another direction... nut in hand 🌰.
Check out this fascinating behavior
Delgado et. al., 2014; Steele et. al., 2014; Steele et. al., 2008
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)
Welcome to Squirrel Gazer!
My name is Amanda and I am a Ph.D. student at the University of California, Los Angeles. I spend most of my days thinking about how animals think and interact with the world. My current research project is exploring the foraging decisions of wild squirrels.
One thing I have learned while working with squirrels is that a lot of people share my love for (and obsession with) squirrels! I would like to use this blog as a platform to share squirrel:
No post would be complete without an adorable photo or video of squirrels. Here, is a short video montage of a family of California ground squirrels (Spermophilus beecheyi) enjoying a meal at my custom made squirrel feeder that collects data. You can find out more about what this feeder does and how it is helping me learn about squirrel foraging behavior here.
This unique species of squirrel lives underground in burrows throughout the West Coast of the United States and Baja California. One cool feature of the Cali ground squirrel is their cheek pouches! If you watch this video closely you can see that not all the squirrels are eating the seeds they find at the feeder immediately... many of them are quickly tucking their bounty in to their cheek pouches and carrying it away for later!
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