One Man’s Trash…
An all too common issue that we often
hear about when discussing urban areas and urban ecology is habitat
destruction. As humans move into an area, we often make those areas unsuitable
for other species to live in. We convert over 4 million square kilometers of
rural land to urban areas every year. One way people try to fix this issue is
by preserving small areas of animal habitat in rural areas, but even this leads
to the issue of habitat fragmentation, causing changes in what lives in the
area and the community structure. Thus, in order for conservation efforts to be
more successful, research must be done on how urbanization has affected and is
affecting community dynamics and species density.
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| Urban raccoon foraging at its finest.
. Retrieved
from
http://www.huntingtonny.gov/images/
EWM/Racoon%20In%20Trash%20Can.jpg
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So, how can we look at this issue with
some common urban mesopredators? Mesopredators are medium sized predators that
benefit from the elimination of larger predators, and I’m sure everyone is
familiar with one specific masked menace. Raccoons are often seen rummaging
through garbage, or roaming around in alleys looking for garbage to rummage through, especially in urban
areas. So, are these fuzzy foragers simply making the best of a bad situation,
or do they choose to live in urban communities? A study by Prange and Gehrt in
2004 determined that raccoons, and to some extent opossums and skunks, may actually
benefit from urbanization. They looked to see if these three species had a
different response to urbanization by live trapping and studying the number of
road-kills in each of several study areas around Illinois, which varied in
their degree of urbanization. They found that there were a lot more raccoons
than anything else, and more raccoons were found at the urbanized sites than
other sites. They concluded that raccoon populations reach much higher
densities in urban areas. This could be because raccoons are more efficient at
using anthropogenic resources than skunks and opossums. According to Prange and
Gehrt, it’s all in their grabby little dexterous paws, which allow raccoons to
knock stuff over more easily. You can find their study here: http://eds.b.ebscohost.com/ehost/pdfviewer/pdfviewer?sid=b72bc8da-f962-46fc-82ff-b02ca56eb702%40sessionmgr115&vid=2&hid=104
In my ecology class, my lab partner and
I decided to carry out an experiment on raccoon foraging in a semi-urban
area. We now know that raccoons are
typically found in greater densities in urban areas, and can easily exploit
resources generated by humans. With this in mind, we hope to find out whether
their foraging behavior is affected by the amount of human traffic in the area
or the distance from a road. Judging from this research it seems that raccoons
don’t really have issues living in habitats modified by humans, but we thought
it would be interesting to see if they preferred secluded urban areas to
exposed ones, or if they take what they can lay their grubby mitts on.
I'm interested in how the authors measured "number of roadkills". I think whether they measured them per square mile of land or per some unit of road would make a big difference. It seems obvious that you would find more roadkill mesopredators in urban areas simply because there are more roads and more opportunities to become roadkill. Not necessarily because there are more mesopredators. Maybe this wasn't the best measure of their abundance in response to urbanization.
ReplyDeleteAs for your study, I wonder what impact it would have if a different type of predator foraged in your research area.
I am curious about whether these creatures are attracted to busier areas because this is where they find trashcans and therefore food, or whether the increased risk of death by car is a factor in their foraging habits. Are raccoons resourceful enough to recognize the increased risk of death in higher traffic areas and go towards more secluded areas. Do the rewards outweigh the risks in this situation?
ReplyDeleteAlso, I'm wondering how many raccoons are actually around Grinnell's campus since it's a pretty rural location surrounded by vast fields of monoculture.
I think Caroline has a good point about the foraging habits, whether it is the greater density of trashcans/food resources that draws raccoons into high traffic areas or if its because they don't recognize the danger. I would be curious as to how you define a high traffic versus a low traffic area. Granted, Grinnell is a fairly small rural town, but wouldn't there be enough urbanization in the downtown area versus residential areas versus corn fields to test your hypothesis?
ReplyDeleteI think that this study would tie in well with looking at rat foraging in urban areas. Like raccoons, rats have the ability to get into places that other animals would not be able to. Although rats do not have as much motor skills in their hands as raccoons do, they are able to squeeze into small areas due to their cone shaped build. Both raccoons and rats seem to thrive in areas with increased urbanization where they can access food that other animals can't.
ReplyDelete