Urban Foxes, page 1
Introduction, About My Study
In the past century, the growing human population has resulted
in an unprecedented growth in cities and associated urbanized
areas. Although these areas are built for and by humans, they
offer shelter and sustenance for a variety of wild animals, and
it is therefore not surprising to see some of these wild animals
inhabiting these cities alongside their human occupants, all the
way to the heart of the city.
Most people are familiar with some city wildlife, to the point
that these animals are hardly considered wildlife any more. The
rock dove, or common pigeon, is one of these, as is the European
sparrow and the gray squirrel. Some animals that are not as frequently
seen, but are no less common, are the house mouse and the brown
rat. In addition, recent years have seen increases in the numbers
of common crows and Canada geese in city areas, and there are
doubtlessly at least twenty or thirty more species of birds and
mammals common to every city that I am leaving out. When I mention
having studied urban foxes, however, people are often taken aback.
Foxes, along with skunks, coyotes, and, to a lesser degree, raccoons,
are still thought of as rural animals, who might live near a farm,
but not a city. In fact, all these animals have diets and behaviors
that allow them to survive in the most unlikely habitats.
Red foxes (Vulpes vulpes) are carnivores in the family
Canidae, along with wolves, coyotes, jackals, and other
foxes. Foxes are generally considered slightly apart from the
other canids, because they share certain characteristics the
rest of the canids do not, such as vertically slit pupils and
lighter bones.
Red foxes are perhaps twice as large as an average housecat,
much smaller than their sometimes thick and bushy coat seems
to indicate. Their distinctive coloration is well known, but subject to
variation; the more familiar russet coat and ivory underfur may be
completely black in some foxes ("silver"), or the russet coat might have
a dark stripe across the shoulders ("cross"). In most red foxes,
the ears and "socks" are black, and in all red foxes, the tailtip is
white (though it is often dirty and hard to see).
Along with the coyote, the red fox is perhaps the most adaptable of
the canids, and it is certainly the most widely distributed in North
America and the world, being found in Europe, Asia, and
Australia (where it was introduced by settlers to control the rabbits
they'd introduced previously). These two canids are the only wild
canid species that are frequently found in urban areas.
In the last twenty years, several studies have examined various
aspects of the life histories of urban foxes, most notably those
of S. Harris of the University of Bristol, and D. MacDonald and
C. Doncaster of Oxford University. All of these were in England,
and none compared urban foxes to their rural counterparts. My
study focused on foxes in the Minneapolis - St. Paul area. I was
interested in how the behaviors of the urban foxes differed from
rural foxes -- what adaptations did foxes undergo to survive in
the city? I decided to focus on parental behaviors; because of
the range of behaviors included in this group, I might more easily
see any differences.
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My goal was to locate five urban den sites and five rural den
sites. Den sites were located by direct investigation of sites
recommended by residents of the metropolitan area and surrounding
rural areas. To pinpoint den sites and areas frequented by foxes,
two field assistants and I searched for signs of foxes such as
tracks, scat, and prey remains.
I planned to make observations weekly at each site for 10 weeks,
from early May until late July. This covers the time period from
the first appearance of the cubs outside the den at about 4-5
weeks of age until the cubs are 14-15 weeks old. The adults no
longer provide food for the cubs after this time, although the
cubs remain in the territory of their parents for another 3 months.
Observations were made by a single observer from a location that
provided a clear view of the den, but was not close enough to
alarm the foxes. Use of a blind was considered, but Henry (1993)
asserted that because foxes have a sensitive sense of smell, a
blind is not very effective in hiding a human observer.
Data recorded during each observation were to be: maximum number
of cubs seen at once, number of times that adults return with
food for the cubs, the type of food brought back by the adults
for the cubs, any food the cubs take for themselves (not provided
by the adults), all intraspecific and interspecific interactions,
and all behavior toward man-made structures. All data collection
was to be made using the cubs as the focal group for observations
and also recording all occurrences of the above behavior in the
adults, as described in Altmann (1974).
In seven weeks of searching the Minneapolis-St. Paul area, my
field assistants and I were only able to locate five fox dens,
two urban and three rural. We found many signs of fox, such as
scat, trails, and prey remains, but were unable to trace these
signs to a den in most cases.
In our initial observations, neither my assistants nor myself
saw any foxes at the dens, although we had seen fresh sign there
recently, and in one case we had seen two fox cubs playing. I
ended my observation of one of the den sites after seeing a striped
skunk enter the den; that was the only wild mammal I saw in several
observations of the urban den sites. We concluded that the foxes
had abandoned the dens. Foxes rearing cubs often move the cubs
to different dens, but in these cases abandonment might have been
precipitated by the disturbance my assistants and I caused while
investigating the den sites.
By the time we discovered that none of the sites we had located
were still inhabited, it was too late to locate more den sites.
By the middle of June, most fox cubs in the Minneapolis-St. Paul
area are between six and twelve weeks old, so even in the best
case, I would be starting my observations in the middle of the
period I was most interested in.
I decided to review the literature on urban foxes again, and see
where the observations I did make fit into other studies. I also
spent some time during the summer working with a woman who rehabilitates
injured foxes and releases them to the wild. Many of the foxes
she receives for treatment come from the Minneapolis-St. Paul
area, so I was able to get a little more data from observing some
of her patients. The most interesting observation I made at this
location was of a young cub, about six to eight weeks old on 5
August. She must therefore have been born in early June, which
is very late in the year relative to birth dates listed in the
literature.
The next sections are my summary of the studies I read on red
fox ecology, with specific mention of urban foxes where applicable.
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