John Porter1 and Raymond Dueser2
1Dept. Environmental Sciences, University of Virginia, Charlottesville, VA 22903, 2Dept. of Fisheries and Wildlife, Utah State Univ., Logan, UT 84322.
In examining the number of individuals encountered on each transect (note: transects have between 22 and 83 traps at 15-m intervals [12.5 m spacing along the transect + 2.5 m off to alternating sides of the transect], with the number of traps being dictated by the width of the island), several clear patterns emerge. First, the number of individuals encountered on a transect is consistently higher in the spring. Note that the number of individuals captured are not adjusted to correct for different numbers of traps between transects and T2 was not trapped during the autumn of 1991 or 1992. Second, during the spring Oryzomys tend to be numerically dominant on the northern transects (T1 & T2), while Mus is numerically dominant on the southern two transects (T4 & T5). During the Oryzomys numbers were reduced relative to other years only on T1 and possibly on T4. Mus numbers were even less effected, with among the highest autumn densities observed immediately after the storm. This observation suggests that for flooding to seriously impact populations it must be either complete or of longer duration than was experienced during the Halloween Storm. For neither Oryzomys nor Mus were spring numbers particulary low in 1992, the spring following the storm.
