Most wild animals move away from areas heavily populated by humans, noisy cars, and sparse natural habitat. Some, however, thrive in the city, learning to hustle to provide for themselves and their families just like the rest of us. Urban wildlife like raccoons and turkeys roam my neighborhood in the San Francisco bay area, stealing food from the compost heap and perching on top of administrative buildings. Other parts of the world see monkeys, moose, or even foxes in their urban centers. Recently, researchers teamed up with citizen scientists to investigate the distribution of urban red foxes in Great Britain. They published the results of their survey in an article in PLOS ONE, “Changes in the Distribution of Red Foxes (Vulpes vulpes) in Urban Areas in Great Britain: Findings and Limitations of a Media-Driven Nationwide Survey.”
Keeping track of animal populations in cities is important for wildlife management and public health, but it is by no means an easy task. Cities are crazy quilts of fences, private residential property, public areas, and commercial property, all with varying degrees of accessibility that can make research on animal distribution a challenge. For these reasons, the authors of this study recruited volunteers to help with the fox survey. Utilizing the eyes and attention of citizen scientists allowed the scientists to evaluate a wide urban area without stomping through everyone’s gardens.
The authors recruited participants using television programs about foxes, with each program including information about how to participate in the fox survey. Participants were asked to submit records and locations of fox sightings with photos via a website. Citizen science makes research like this possible, but it does have drawbacks, including that the data quality relies on the accurate reporting of many untrained individuals who are much more likely to report positive data points (such as the presence of a fox in their area) rather than negative data points (an absence of foxes), which can skew results.
To improve data reliability, researchers double-checked for errors in location and date. They focused on determining how widespread the foxes were, which is easier to gauge with this method, rather than how densely populated the foxes are, which would be more difficult with potentially skewed data.
The results of this study indicated that, compared to their distribution in the 1980s, foxes have further spread out over Britain, with sightings reported in 91% of 65 cities that were previously thought to have few or no foxes. It is unclear why they have expanded their colonization of British urban areas, but according to the authors they do seem to prefer private backyards to public green spaces. More fox sightings were reported in cities with higher human population densities, as can be seen in the graphic above, but the researchers noted that this result could easily be due to increased reporting and not necessarily related to a higher number of foxes. All in all, more research is needed to determine why the distribution of red foxes in Britain is changing, and whether the fox population is increasing or just spreading out. In the meantime, the authors have made their data available for anyone to have a look.
Scott DM, Berg MJ, Tolhurst BA, Chauvenet ALM, Smith GC, et al. (2014) Changes in the Distribution of Red Foxes (Vulpes vulpes) in Urban Areas in Great Britain: Findings and Limitations of a Media-Driven Nationwide Survey. PLoS ONE 9(6): e99059. doi:10.1371/journal.pone.0099059
Flickr image “Oops, I woke up the Fox asleep by my backdoor” by Steve K
Fox sightings map figure is from the article