Ethogram of Gray Squirrels on Campus

I observed the behavior of squirrels in various areas around the Shippensburg University campus during different times of the day.  These observations started taking place in the beginning of March 2011 and ended in the middle of April 2011.  I grouped all the behaviors I observed into four categories, but did not separate the behaviors into those performed in the presence and the absence of other squirrels.  The following ethogram is the results of the observations.

Posture

·         Freeze:  remain in same position for more than 10 seconds without moving

·         Stand:  move from being on all four legs to putting weight on just the hind legs

·         Sit:  posterior is placed on the ground and front legs are off the ground

·         Crouch:  all four legs are on the ground and body is close to the ground

·         Hunch:  same as sitting but with body closer to the ground

Tail

·         Straight out

·         Moves in circular pattern

·         Flicks side to side

·         Waggles in a wave

·         Swishes side to side (more force than a flick)

·         Curled under

·         Curled over

Feeding

·         Dig

·         Bury

·         Nibble

Traveling/maneuvers

·         Scurry:  moves in no particular direction

·         Walk

·         Run

·         Climb

·         Jump

·         Flip

·         Pounce

Are campus squirrels less likely to freeze than other squirrels when seeing a human?

Introduction

                It was observed that squirrels will sometimes “freeze” after they have been running, climbing, ect.  When they do this, they will not move any body part for at least ten seconds.  It seems that in general, animals will do this as a way to confuse or hide from a predator.  On a campus community, however, squirrels will tend to be less afraid of humans and movement than squirrels in less urban areas.

Materials and Methods

                To test this hypothesis, squirrels would need to be observed on campuses and rural areas.  The number of times that a squirrel is seen freezing for ten or more seconds would need to be recorded.  To be consistent, the same number of squirrels would need to be observed in each area and the observing would need to take place during the same time of day.  Once a squirrel is spotted in motion, have a human quietly start to approach the squirrel.  Record whether or not the squirrel freezes or continues to move.  The human should wear the same clothing each time and not carry any objects.  One error with this experiment that is unable to be avoided is the distance from which the squirrel will spot or hear the human approaching.  The variability in distances may be one factor that influences the squirrel to freeze or continue moving.  Since there are only two variables with this experiment, a t-test could be performed for statistical analysis.

Blanchard, D., Griebel, G., Pobbe, R., & Blanchard, R. J. (2011). Risk assessment as an evolved threat       detection and analysis process. Neuroscience & Biobehavioral Reviews, 35(4), 991-998. doi:10.1016/j.neubiorev.2010.10.016

Do squirrels only dig up the food that they bury or will they dig up any food they find?

Introduction

                Squirrels can be seen running all over the ground in search of buried food that was buried for storage.  It takes time and energy for the squirrel to dig for buried food that they first had to spend time locating.  They are able to locate underground by smell and memory.  I hypothesize that squirrels will not only eat the food that they have buried, but also food that another squirrel has buried.  By doing so, the squirrel is able to ensure that it will be fed.

Materials and Methods

                Squirrels will need to be captured and tagged with some kind of identifying marker.  They will then need to be constantly monitored to see where they bury food in a designated area.  Once a squirrel does bury food, that spot will be marked with a corresponding identifier.  Those areas will then need to be monitored as well to see which squirrel digs up the food.  Once data has been collected, analysis can be done to see if the marked areas were dug up by the same squirrel that buried food there.  The percentage of sites dug up by the same squirrel that buried the food can then be compared to the percentage of sites dug up by a different squirrel than the one that buried the food. 

Huang, Z., Wang, Y., Zhang, H., Wu, F., & Zhang, Z. (2011). Behavioural responses of sympatric rodents to complete pilferage. Animal Behaviour, 81(4), 831-836. doi:10.1016/j.anbehav.2011.01.018

Jacobs, L. (1989). Cache economy of the gray squirrel. Natural History, 98(10), 40. Retrieved from EBSCOhost.

Does the rate at which a gray squirrel flicks its tail correlate with aggression?

Introduction

                While observing squirrels, it was noticed that they will flick their tails when in the presence of another squirrel.  This flicking of the tail was either followed by one of the squirrels leaving or both the squirrels chasing each other.  It appeared that the squirrels would flick their tails at different rates and sometimes the rate of flicking would increase as the flicking action continued.  The tail flicking seems to be a form of communication between the squirrels.  I hypothesize that the faster the rate of flicking, the greater the next action is followed by the tail-flicking squirrel to attack or the non tail-flicker to retreat.  These behaviors would indicate that tail flicking is a way to communicate aggression.

Materials and Methods

                To test this hypothesis, two squirrels are placed in the same enclosed area, perhaps 15x15 meters.  In this enclosure one food source, like a bird feeder is placed.  Both squirrels would then be monitored by for tail flicking.  Once tail flicking in one squirrel started, the rate of flicking would be measured by how many times the tail is flicked to the right in 30 seconds.  Then the behavior of both the squirrels would be recorded after the tail flicking stops.  This experiment would continue with two different squirrels and then two others until a strong sample size was collected.  During analysis, the rate of tail flicking would be compared to the number of times that the tail flicking was followed by either an attack/retreat and compared to the tail flicking being followed by any other action.  The rates of tail flicking would be categorized as either slow, moderate, or fast.  A bar graph could be used to show the number of times in which a slow rate was followed by an attack/retreat or other action, the number of times a moderate rate was followed by one of those actions and the same for a fast rate.  A t-test could be used to determine if the findings are significant.

Prado, Mickey. "A Statistical Analysis and Decoding of the Tail Communication System

of Eastern Gray Squirrels (Sciurus carolinensis)." Web. 19 Apr. 2011. <http://www.amstat.org/education/posterprojects/projects/2008/7-Grades10-12-ThirdPlace.pdf>.

Are squirrels more likely to climb a tree to eat food when there are people around?

Introduction

                Animals become very territorial when it comes to eating their food.  Squirrels are no different.  They do not share their food with others and will eat alone.  While observing them, the squirrels would sometimes eat their food on the ground and other times they would climb a tree with their food before consuming it.  I hypothesize that a squirrel will decide to climb a tree to eat its food whenever it notices a human nearby.

Materials and Methods

                A possible experiment for this hypothesis would be to observe squirrels when they are eating both in the presence and absence of a human.  In order to watch a squirrel eating without being detected by the squirrel, a video camera would need to be set up.  For observations with a human presence, the human would need to make sure that the squirrel notices the human.  Each squirrel observed would need to be watched for behaviors both with and without the human being present for multiple trials.  A t-test could then be used to determine if there is a significant difference between each individual squirrel’s choice of whether to eat on the ground or climb a tree.

Jacobs, L. (1989). Cache economy of the gray squirrel. Natural History, 98(10), 40. Retrieved from EBSCOhost.

Do squirrels use their tail as a way to communicate to other species?

Introduction

                It has been found that tail movements are a way for squirrels to communicate to each other.  However, it is not known if squirrels use their tails to communicate with other species.  I hypothesize that a squirrel will display similar tail movements in the presence of other species that they display when other squirrels are around.

Materials and Methods

                The squirrels will first need to have their tail movements recorded while they are around other squirrels and an ethogram will need to be made from these tail movements.  The squirrels will then need to be isolated from each other.  Then different species (a human, cat, dog…) will be made visible to each squirrel and the tail behaviors recorded.  Also, the squirrels’ tail behavior will need to be recorded when they are alone to determine if there are movements that they perform with their tails that are not forms of communication.  A t-test would be used for statistical analysis.

Prado, Mickey. "A Statistical Analysis and Decoding of the Tail Communication System

of Eastern Gray Squirrels (Sciurus carolinensis)." Web. 19 Apr. 2011. <http://www.amstat.org/education/posterprojects/projects/2008/7-Grades10-12-ThirdPlace.pdf>.

Is pouncing more of a play, aggonistic, or courtship behavior?

Introduction

                Squirrels are very active creatures, but not usually social.  When they are interacting with each other, they can be seen pouncing on top of each other.  Squirrels, when they do interact, are known to play and fight with each other as well as engage in courtship behaviors.  I hypothesize that when squirrels pounce on each other, they are playing rather than being aggnostic or displaying some kind of courtship.

Materials and Methods

                Squirrels will first need to be observed pouncing on each other.  Once the pouncing has stopped, the sex of each squirrel will need to be determined.  Squirrels of the same sex that are pouncing on each other would rule out the possibility that pouncing is a kind of courtship.  The age and kinship of the squirrels would also need to be determined.  If squirrels that are pouncing on each other are from the same dray, it is possible that they are pouncing for play.  If the pouncing action is followed by a more aggressive act or results in one squirrel running away, it’s possible that the pouncing is a fighting behavior.  Two dominant squirrels could also be placed together with a food source to see if they engage in fighting behaviors and if so, is pouncing a behavior performed by one or both squirrels.  A Chi-square test could be used for analysis of the collected data.

Pasztor, T. J., Smith, L. K., MacDonald, N. K., Michener, G. R., & Pellis, S. M. (2001). Sexual and aggressive play fighting of sibling Richardson’s ground squirrels. Aggressive Behavior, 27(4), 323-337. Retrieved from EBSCOhost.