Laura Dean, Heather Miller
Jill Dann, Cleveland Dodds
The Impact of Humans on the Domestication of Squirrels
Because of urbanization, humans are having a greater effect on the wildlife populations in these developed areas. We are attempting to prove this by testing the distance that a squirrel will allow a human to approach. We will be testing squirrels found on Miami University's campus and squirrels found in the wooded areas of Pfeffer Park to prove our hypothesis that squirrels in heavily populated areas will allow closer interaction than those in secluded areas. We will also measure the distance of the nearest refuge to the squirrel. We have also hypothesized that a closer refuge to the squirrel will allow closer interaction on the part of the humans.
By looking at the distribution of gray squirrels, we have found that the Midwest and some southern areas are heavily populated (Smith, Andrew T.B. and Donald A. Smith). Gray squirrels often live in city parks and suburbs where large nut and shade trees offer food. Oakes, Beeches and Hickories are preferred by frequently gray squirrels live where these trees are mixed with other hardwoods and sometimes pines and other conifers (MacClintock, pg. 105). Results of an experiment conducted in the Eastern Sierra Madre, Mexico, suggest that squirrels can be found more easily in areas where food availability are the greatest (Steele, pg. 113). Most gray squirrels eat wild fruits, nuts and berries, bark and twigs, sap and during the summer they eat wild grapes, pokeberries, hackberries, and wild cherries. In previous studies, the distance between a squirrel and its refuge has an affect on how close they will allow a human to approach. Animals in danger of predators need to decide how close they will allow those predators to come. For animals that run to a refuge to escape their predators, risk increases with the distance to or rime from the refuge. As the distance decreases between the predator and the animal and the risk of capture increases, then animals far from a refuge should have longer flight initiation distances than those closer by (Dill, Lawrence M. and Robert Houtman).
How do squirrels' reactions to humans differ between wilderness and urbanized areas? Will squirrels allow us to approach them at a closer distance if they live in an area heavily populated? Does having a refuge nearby affect the distance in which a human can approach squirrels? We believe that squirrels living in environments heavily populated by humans will allow closer interaction with humans than squirrels found in less populated areas. We also believe that if the squirrel has a close escape to a refuge near by, it will allow a human to approach closer.
When writing this lab, we tried to think of ways in which humans affect their own environment. We then narrowed our topic to focus on the human impact on wildlife. While looking at the variety of wildlife on campus, we discovered that squirrels are easy to find and we could use them as test subjects. By doing this lab, we hope to discover if humans have an impact on the behavior of squirrels. The significance of this project is to see if the campus and its location have a great impact on. Does domestication have an effect on the natural behaviors of squirrels? For example, does human interaction cause squirrels to allow predators to approach at a closer distance endangering their lives and habitats?
In our experiment, we are going to explore two different locations in the Oxford area that reflect a different amount of human contact. We need to explore different areas in order to observe the differences that location has on squirrel behaviors. The two locations are: Pfeffer Park, in the woods and the Miami University Campus. In each section, we will test 30 squirrels in random patterns in order to get an accurate sample of data. To begin testing, locate a squirrel and approach it at a steady rate. A steady rate is defined as counting "one-Mississippi" between each step. When the squirrel begins to run away, have the person who is approaching stop in their position, and have another person observe the position of the squirrel before it begins to flee. Then measure the distance between the person approaching and the point at which the squirrel began to run. Also measure the distance between where the squirrel began to flee from to a place of refuge for the squirrel, such as a tree. (To see a diagram of these measurements, refer to Figure 1.) This information is valuable because the squirrels may allow a person to approach at a closer distance if the squirrels know that a place of refuge is close by.
In order to measure the difference between the park data and campus data, we will run a t-test between the approach distances of squirrels for both areas. The null hypothesis is that there is no significant difference between the means of the behavior of squirrels on campus and the means of the behavior of the squirrels in the park. If the p-value is less than 0.05, the null hypothesis will be proved wrong and it can be concluded that there is a significant difference between the behavior of squirrels on campus and in the park. To determine if the distance between the squirrel and the refuge has any impact on the distance the squirrel will allow a human to approach it at, we will run a t-test. The null hypothesis is that there is no significant difference between the mean distance that the squirrel is from the human and the mean distance between the squirrel and its point of refuge. By analyzing our data, we will be able to determine how great of an impact humans have on squirrels. We believe that our experimental design is statistically sound because the number of squirrels tested is sufficient enough for us to prove our hypothesis. Our results will not be biased because we have laid out specific instructions for collecting random samples on and off campus and for conducting the experiment.
Summary of Class Participation:
During our lab day, we will divide into two groups and depart to different locations on campus. These locations will be determined at a later date depending on which section of campus we are lacking data from. In each section, the class will split into groups of three and use the methods previously stated to help us collect data on our data sheets. We will ensure that the data the class collects can be trusted by demonstrating the methods they should follow.
At the beginning of this lab, we based our experiment on the hypothesis that squirrels on main campus would be better adapted to humans than the squirrels in Pfeffer Park. After collecting all the data, we found that squirrels on main campus allowed us to approach them to a point 9.2 ft. away on average. The squirrels in Pfeffer Park allowed us to approach them to a point 16.9 ft away on average. (See Figure 2 for our data.) Figures 2 and 3 show the distribution of distances between squirrels and humans. After running a T-test (See Figure 4), we found a p-value of 0.0080. Because this number is less than 0.05, we have disproved our null hypothesis that there is no significant difference between the means of the behaviors of squirrels on main campus and the means of the behaviors of squirrels in Pfeffer Park. Therefore, we may conclude that humans do have an impact on the behaviors of squirrels.
Although the first half of our experiment showed that squirrel's behaviors are affected by human contact, we wanted to test another theory on why squirrels behave the way they do. To do this, we measured the distance that the squirrel was from its nearest refuge point before it began to run. (To see the data from this test, refer to Figure 2.) We believed that this refuge point would allow humans to get closer to the squirrels if their refuge point was at a close distance. To determine if this hypothesis was valid, we ran a t-test between the distances that the squirrel is from the human and the distance between the squirrel and its refuge. After running the t-test, we found the p-value to be 0.2187. Because this value is more than 0.05, our null hypothesis is proved correct. Therefore we cannot conclude that the point of refuge is a significant factor in the behavior of squirrels when approached by humans.
By doing this lab, we have discovered that humans do contribute to the domestication of squirrels. From the methods used in this lab, we cannot determine the exact reasons that the presence of humans affects the behaviors of squirrels. Whatever the reason, be it food, a loss of a sense of predation, or architecture that may attract squirrels, humans do have an affect on squirrel behaviors. Although we could not prove that the refuge distance plays a role in the distance that a human can approach a squirrel, further research could still support that idea. Squirrels are a part of our everyday environment, through this lab; we now have a better understanding of how we affect the wildlife around us.
September 27 through October 15: Do research on squirrels
October 4 through November 7: Collect all data on squirrels in the area
November 7 through November 31: Organize and write lab results and final papers
Dill, Lawrence M. and Robert Houtman. "The influence of distance on flight initiation distance in the gray squirrel" Canadian Journal of Zoology 1989: v67: p233-235
Gustafson, Eric J. and Larry W. VanDruff. "Behavior of Black and Gray Morphs of Scirurus carolinensis in an Urban Environment" The American Midland Naturalist January 1990: v123: p186-192
MacClintock, Dorcas, Squirrels of North America. Van Nostrand Reinhold Company, New York, 1970.
Sharpe, Peter B. and Beatrice Van Horne. "Influence of Habitat on Behavior of Townsend's Ground Squirrels (spermophilus townsend II)" Journal of Mammology August 1998: v79: p906-918
Smith, Andrew T. B. and Donald A. Smith. "Mammals" homepage: http://www.cciw.ca/eman-temp/reports/publications/Mixedwood/mammal/intro.htm
Steele, Michael A., Joseph F. Merritt, and David A. Zegers ed. Ecology and Evolutionary Biology of Tree Squirrels. Virginia Museum of Natural History, 1998.
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