Geography Reference
In-Depth Information
but even to a more extreme degree. In the city, no native species were found—
only house mice, Norway rats, and black rats.
Checking live traps in the morning is one of my favorite jobs. Like Christmas
morning, one never knows what the shiny packages will contain. A closed trap
door suggests that something is inside, and as I lift up the gift, I know when
it's something special. A heavy box is likely to hold a sleek weasel. My heart
races as I push in the door to sneak a peek, and then my brain starts to i gure
out how to get the weasel out of the small box and back into the brush rather
than up my pants leg. A light one probably holds a mouse that will need to be
weighed, marked, and released. When I checked the twenty-four traps I set out
in early August 2000, most were closed, and all were light. The number of
white-footed mice, commonly called deer mice, that I caught was staggering:
thirteen the i rst day. A second day produced similar results: six new mice and
seven that I had caught and marked the previous day. The third and last day
yielded four new and nine known mice. My traps covered an area about the
size of an American football i eld's end zone within a small suburban forest
patch a tenth of an acre in size. The twenty-three mice I caught there meant
that in each area about the size of a standard hotel room, one could expect to
i nd a mouse. No wonder coyotes and bobcats often surprised me during early
morning bird counts! Many other mammals that exploit a city's abundant
food and shelter reach densities on par with that of the white-footed mice
I trapped.
In Lafayette Square, which is adjacent to the White House, every acre holds
twenty or more eastern gray squirrels—ten to twenty times that of rural
