Each rabbit is tagged with a unique number. The ear tag on the left is red, indicating the rabbit was seen in 2012. Photo by Marian Vernon.
Eastern cottontail rabbits are year-round denizens of Nature Boardwalk at Lincoln Park Zoo and its surroundings. In the Urban Wildlife Institute, we’re interested in understanding how animals in urban areas like Chicago can survive and sometimes even thrive (as is true of cottontail rabbits). Toward this end, since January 2010 we’ve been conducting a long-term study of cottontail rabbits around Lincoln Park Zoo.
One aspect of the study involves applying ear tags to a subset of rabbits in the local population. The color of the tag indicates the rabbit’s year of capture. Each tag has a unique number so the rabbits are individually identifiable. From this, we estimate how many rabbits make their home at Lincoln Park Zoo and track changes in their population size over time.
An interesting outcome of this study is that we get a sense of the home range of these rabbits. In some cases we’ve encountered the same rabbits over multiple years. We frequently caught the same individual rabbit at the same exact location, despite having traps distributed all over the zoo.
Over the course of the study we sampled locations all over the zoo's main grounds.
Three rabbits were caught in 2010 and again in 2012. These rabbits were found at locations that differed by only 50, 30 and 80 meters (moving from top to bottom of the map).
As you can see, rabbits were in nearly the same locations in 2010 and 2012, despite the elapsed time and the fact that we sampled all across the zoo. Rabbits typically live less than one year, so these three rabbits have already exceeded the life expectancy for the species.
We don’t know where the rabbits go when we aren’t sampling. And there are a handful of exceptions to the rule where we’ve trapped the same rabbit at opposites sides of the zoo. But for the most part these rabbits seem to have very localized movements. Just imagine living your entire life within 100 square meters!
The population estimate for 2012 is a work in progress. Stay tuned for more information on this study!