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I plan on studying shorebird diversity at the Don Edwards San Francisco Bay National Wildlife Refuge. In particular, I plan on studying shorebird diversity attributes such as species richness, species abundance, species evenness, etc. in response to human presence. In order to study the response of shorebird diversity to human presence at this wildlife refuge, I chose three study locations with varying degrees of human presence across the marsh at the south end of the refuge. A map of the refuge with my chosen study locations are depicted in Figure 1. Location #1 is bordered by a highly urbanized environment, representing the peak of the gradient of human presence. Location #2 relatively closed off from human presence as it is bordered by a wet open grassland which is intersected by a road that leads to the wildlife refuge’s visitor center. This area does not house any trails or walkways and was chosen to represent a minimum of the human presence gradient. Location #3 borders the visiting center and houses walking trails, boarded pathways and bridges for visitors to explore the refuge, observe wildlife, etc.. I assumed that this location would represent an intermediate measure of human presence as this location only houses a visitor’s center and walking trails (minimal urbanization and much less human presence than the urban area bordering location #1). Figure 2 depicts my notes of observed shorebirds in the 3 study locations.
I hypothesize that one underlying process that may be influencing changes in shorebird diversity across a gradient of human presence (or nearby urbanization) may be an intolerance of the local refuge’s shorebird species to urban life or human presence. Such intolerance may arise from habitat disturbance, pollution, noise, etc.. Based on this hypothesis, I predict that measures of shorebird diversity such as shorebird species richness, species evenness and species abundance should decrease with increases in human presence or urbanization. Specifically, Location #1 (nearby an urbanized environment) should have the least shorebird diversity and Location #2 (little to no human presence) should have the highest measures of shorebird diversity. Furthermore, Location #3 (containing walking trails and human visitors, with little urbanization) should have intermediate measures of shorebird diversity. Based on this hypothesis and predications, one potential response variable would be species richness (a measure of shorebird diversity) which would be a continuous variable. One potential explanatory variable would be the study location which corresponds to particular amount of human presence (Location #1 – high human presence, Location # 2 – little/no human presence, Location #3 – intermediate human presence), which would be a categorical variable.
Figure 1. Map of the Wildlife Refuge at the south end of the San Francisco Bay. The three study locations at which I studied shorebird diversity are depicted by squares (red being location #1, pink location #2 and purple being location #3).
Figure 2. Notes of shorebird observations at 3 study locations along the wildlife refuge south marsh.
