When two different species live in the same habitat they often have to compete with one another to gain access to important resources like food 🥜🍄🍩
The need to out-compete others may lead animals to change their behavior in order to obtain more than their neighbors or at the very least what is required to survive.
Over the summer, one of my research assistants and fellow squirrel gazer 🐿👀, Katie Elliot, explored how the California ground squirrel and their pesky neighbors the Stellar's Jay may alter their foraging strategies to outcompete one another at a mutual food source.
The California ground squirrel and Stellar's jay coexist in many mountainous regions of California and have very similar diets, possibly causing rivalry for mutual food sources 🐿🐦
For 8 hours a day, for 5 consecutive days, Katie placed out a feeding tray with a variety of food options for squirrels and jays to select from.
A camera placed above the tray allowed Katie to analyze how members of both species used the food source.
By watching all 40 hours of footage in slow motion, Katie was able to record six different variables from the footage:
(1) The species of visitors visiting the tray 🐿🐦
(2) The food item selected by each visitor 🥜🌰
(3) The time of day the visit was made to the tray ☀️🌙
(4) Why the visitor left the tray. Did it become satiated? Or was it kicked out by another animal?
(5) How many other indviduals would a visitor allow to eat at the tray with them? 🐿🐿🐿
(6) Was the visitor aggressive to others? 😡
The results are in!
California ground squirrels and Stellar's jays did compete with one another for the same food items
This graph shows that both squirrels and birds selected relatively the same food items from the feeding tray. Out the of the over 700 visits to the tray that Katie observed there was no clear difference in the favorite food option between the two species.
The squirrels and the birds used different foraging strategies to compete with other animals!
Squirrels Foraged Early and Ate Together
Ground squirrels were more often observed approaching the tray in groups compared to Stellar's Jays who appeared to prefer to arrive at the tray alone.
From this graph we can see that ground squirrels only visited the feeding tray in the morning, while Stellar's Jays stopped by throughout the day.
Stellar's Jays Foraged Alone and Aggressively
Pictured above is a Stellar's jay performing an aggressive display (right) towards another jay that just arrived at the tray (left).
This graph shows thats Stellar's jays aggressively kicked-out or displaced both squirrels and other jays from the tray at higher rates than ground squirrels. Ground squirrels were never observed behaving aggressively towards jays, but on occasion would chase away other squirrels.
Based on these findings, Katie concluded that ground squirrels and Stellar's jays do indeed modify their foraging behavior in order to compete with one another at a shared food source. However, each species used a different strategic approach.
Squirrels would travel in groups and take over the tray in the mornings. Whereas, jays would forage alone throughout the day and behave aggressively towards other animals that approached.
This simple project highlights just a few of the many ways animals adjust to and compete with one another to survive.
To learn more about Katie Elliot check out her profile HERE.
Katie became a member of the Squirrel Gazer Team through the Community College Field Biology Alliance, a 9-month intensive research program at UCLA that connects community college students with research opportunities in field biology.
If you or anyone you know is a community college student in the greater Los Angeles area interested in research, please visit or share the website posted below! Applications for the 2020 program are open until February 1st!
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