Shopping with Spectators: Our new experiment to see how social factors influence the food storing decisions of western grey squirrels
The beautiful western grey squirrel is a California native tree squirrel species that is very active at my favorite research site, the UC James Reserve in the San Bernardino National Forest in Southern California 🐿🌲. You can learn more about this illusive species in our previous posts on their habitat use and in our squirrel profiles!
One of many super interesting facts about these fluffy tailed cuties is that they do not hibernate over the winter when the mountain is snowy 🏔 During that time there is very little food available in the environment, so in order to survive they have to bury enough food to make it through the season.
But how do they decide when to eat an item and when to store it?
When a squirrel finds a food item it can choose to eat it right away or store it by burying it underground to eat later. The burying of items by squirrels for future use is typically called 'caching' by Squirrel Gazers 🐿👀
The decision to eat or cache something is a complex one that is influenced by many different factors including the food item's quality, size, and condition. Check out our post from 2019 to see a little more on some of the assessment behaviors squirrels perform to "quality check" their nuts! 🥜🔍🐿
In this new experiment we are intersted in learning more about how having an audience of other squirrels or birds would impact the decision to eat or store a food item. After all, squirrels are known thieves and burying something while others are around may increase the chance that nut is stolen.
To explore more about how the presence of other animals might influence a squirrels preference for eating or storing food, we set out an automated feeding station 🥜🤖
The black and red rectangle you see there is actually a microchip scanner! The squirrels at our field site have been implanted with Passive integrated transponders or "PIT-tags". This is just a science term for saying microchip!
These are the same type of microchips we put in our cats and dogs. These tags allow us keep track of the squirrels in our area and identify them when they appear at the feeder.
And yes, all our squirrels have names! That is Han Solo there in the photo! 🐿💕
Surrounding the microchip scanner are several cameras that record what the squirrels are doing while at the feeding station.
The squirrels are given an important choice at the feeder.
California grounds squirrels are super cool for so many reasons! 🐿Here are two of my favorite fun facts about this species:
(1.) They are semi-fossorial, this means that they live both above and below ground.
(2.) They are ecosystem engineers, this is a special title given to species that make changes to their habitats that can have large impacts on other species. The burrows ground squirrels dig provide homes for lots of other California native wildlife like burrowing owls and rattle snakes. 🦉🐍
Scientists know a lot about how the burrows created by ground squirrels help improve the lives of the other species of mammals, birds, and insects that call these burrows home or use them to find food.
However, we know a lot less about what these underground burrow networks look like and if there are differences between how squirrels build and use this secretive space.
Over the summer I paired up with expert Squirrel Gazer Dr. Jennifer Smith 🐿👀 to track the underground pathways taken by California ground squirrels using motion sensing collars.
Dr. Smith is a professor at Mills College in Oakland, California. She has established a long-term study population of wild ground squirrels at Briones Regional Park. Check out her website to learn more about her amazing squirrel science and team of undergraduate squirrel gazers 🎓🐿!
High canopy connectivity is another way of saying 'a lot of connected branches.' Tree squirrels prefer to travel up in the trees to avoid predators on the ground. They use this interconnected branch network as a super highway to move through the forest. In order to do this they need large areas that have a lot of mature trees whose branches overlap. Research has shown that squirrels prefer to leap about 3 feet across at the maximum . Thus, an area with high connectivity would have lots of branches at this distance or less.
Along with finding Petry, Lisette found a second baby squirrel in her yard who she named Ducky. Ducky did not appear to have any obvious bone injuries and was not bleeding or crying. As Lisette approached Ducky he began to move on his own.
If you come across a baby squirrel like Ducky who does not appear to need immediate medical care the best option is leave the squirrel where you found it. Keep people and pets away from the area for a day and give the mother squirrel a chance to come back and relocate her baby. 🐿💕👼 If it is very cold outside it may be a good idea to place the baby on a blanket.
If by the end of the day the mother has not come back it may be time to bring the baby squirrel to a rehabilitation center as it will likely not survive the night outside on the ground alone.