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Urban Squirrels

Urban Squirrels

Environmentalists have focused on protecting wildlife areas, limited natural resources and other important aspects of nature. We have laws, practices and norms regarding our environment and how we interact with it. From fossil fuels to our national parks, our efforts are limited in their scope. Unfortunately, the minority have recognized that while as a population, we have urbanized and built cities, the habitats of animals have disappeared. Many of these species either relocated to rural areas or adapted to the hustle and bustle of city life. Yet, in some cities we actually have problems with the animals due to their overpopulation. The nice, fluffy squirrel has caused problems, such as chewing electrical wires and irrigation pipes in parks, in and around the Washington D.C. metropolitan area due to overpopulation (Gustafson and VanDruff, 1990). It just so happens that squirrel population density is much higher in urban areas than in rural areas. In rural areas, squirrel density is approximately one to two per acre while up to five or six squirrels per acre can be found in urban areas (Harestad, A. 1990). Often the squirrels live in parks but can also live in abandoned homes or other human-built environments. The most favorable conditions for the squirrels in a city are where there is a good density of trees at a certain height. Squirrels’ nests, even in an urban environment, are built in the same manner as rural squirrels, typically made out of sticks and leaves. Urban squirrels also store nuts and berries underground like their rural counterparts. However, humans cause urban squirrels to change their social patterns due to the overall nature of a city. It has been shown that urban squirrels can have a shift in their diet and their nesting materials or locations and altered behaviors such as a reduced fear in man and aggressiveness to other squirrels (Faeth, 2005). The question remains is to what extent do humans affect the nesting patterns and behavior or urban squirrels?

In this question, the nesting patterns of urban squirrels would be first and very important. Information about favorable conditions for squirrel nests would allow humans to successfully manage squirrel populations. Through limiting the density or height of trees, the squirrel population can be reduced so as to prevent squirrel related problems in urban areas. Yet urban squirrels will always be present so we need to find the knowledge on how they behave to our management efforts will be needed. First, I hypothesize that there is a positive correlation between the density of squirrel nests and the height and tree-density of the surrounding area. Second, I hypothesize that there is a positive correlation between certain behaviors and the frequency of pedestrians in the area. Third, I hypothesize that the altered behaviors of the squirrels will correlate with higher tree-density and higher pedestrian traffic.

The experimental design would take place in sections at different areas with varying tree densities, pedestrian paths and closeness to human businesses. Divided into sections, I would start finding the tree characteristics like height and number within the area to conduct my research. To determine tree height, I would use the angle of elevation method, which makes it possible to ascertain the height of a tree by a trigonometric function. I would then ascertain the number of trees in that area by counting. After determining the height and density of trees in a certain area, I would need to determine the density of the squirrel nests through counting and observation. If the data indicated a correlation between the number of squirrel nests and the height and density of trees then my first hypothesis would be proven correct.

These sections, I would then determine the frequency of pedestrians traveling through one area. Measuring the number of people in an area during various times of the day and night, would give an accurate estimate of the general traffic of that section. Using a proportion between the number of pedestrians and the number of squirrels for a given area, I would then try to identify certain behaviors. Any run-ins between squirrels that display an agonistic or fighting behavior will be documented as an aggressive behavior. Then I would test this aggressive behavior with regards to food opportunities. I would set up “leftovers” from a meal and document the squirrels’ behaviors. Measuring the level of aggression in regards to the possibility for food will be considered in contrast to other instances of the same or similar behaviors. Also, the wariness of the squirrels in regards to humans will be tested. By having an individual approach a squirrel at a set pace, multiple times (for different squirrels), I can measure the reaction time and their resulting behavior. If the data indicated a correlation between the pedestrian traffic and the altered behaviors of the squirrels, then my second hypothesis would be proven correct.

I would then take the results from this behavioral part and the initial population density part and cross-examine the areas to see any patterns. If the data indicated a correlation between the altered behaviors, pedestrian traffic and the tree-density, then my third hypothesis would be proven correct. The implications of this are that the urban animals have a higher degree of changed behaviors in correlation with high density, high pedestrian trafficked areas. In this way, we could ascertain and create methods for effective urban squirrel control due to these factors to prevent more squirrel-caused problems. Some options for this are reducing the height of trees, reducing the number of trees in an area and removing or narrowing some pedestrian walkways.

Harestad, A. “Nest Site Selection by Northern Flying Squirrels and Douglas Squirrels.” Northwestern Naturalist, Vol. 71, No. 2. (Autumn, 1990), pp. 43-45.

Faeth, S. H., P. S. Warren, E. Shochat, and W. A. Marussich. 2005. Trophic dynamics in urban com‐ munities. BioScience 55:399–407.

Manski, D. A., L. W. VanDruff, and V. Flyger. 1980. Activities of gray squirrels and people in a downtown Washington, D.C. park: Management implications. Proceedings of the Forty-Sixth North American Wildlife Conference, 46:439-454.

“Angle of Elevation.” Mathwords. Web. 14 Oct. 2011. .

2 Responses to “Urban Squirrels”

  1. Rachel says:

    Jeff, I like how you introduce your topic. First, you bring out a topic of interest that is often unnoticed. Then, you give background and offer information relating to the importance of addressing the problem. After that, you give your hypothesis, proposal, and so on. Altogether, it is very coherent and nicely laid out.
    When you are describing your experimental design, I wouldn’t mind seeing less “I’s.” It chops up the flow of the blog and feels a bit too colloquial for the purpose of laying out a research plan.
    When you measure the number of pedestrians in an area, the idea is well thought out. However, it is important to give a more description of how large an “area” is explain why you chose an area of this size. Also, I wonder if the effects of squirrel overpopulation changes from different urban areas? There are over two hundred kinds of squirrels with varying behaviours and diets. (I would know, my research plan was on squirrels as well.) In my opinion, if you addressed this issue and explained why or why not it was important, your justification would be strengthened even more.

  2. Gavin says:

    Hey Jeff,
    Cool ideas in this experiment. I liked all of the different theories and hypotheses that you developed based on your research. It seems like you really developed your thoughts in relation to the urban squirrel dilemma. One of the issues of your experiment (and an issue with the possible solutions) is the practicality of decreasing tree density and human traffic in response to a squirrel problem. I’m not sure that removing trees and controlling human movements in the parks are policies that a city would invest in because of the fiscal difficulties and the resistance (mainly from residents who frequent the parks) you would receive. The research is interesting and I’m interested to see the results, but a realistic solution would need to be thought up.

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