13G Bulletin Wisconsin Natural History Society [Vol. 13, No. 3 
the swamp, the weasel still preying upon the vole. In the 
meantime the now watery swamp has been possessed by the 
muskrat which has come out of hibernation, together with an 
occasional mink. As the swamp dries, the muskrats diminish 
in abundance, until their excursions are confined to the edge 
of the swamp nearest to the lake, where they remain all summer. 
With their retreat, the advance of the weasel and the vole 
begins, and in the fall or late summer they are once more in 
possession. Late in the summer another species may be found 
at the woody edge of the swamp when the white-footed deer 
mouse ( Pecomyscus leucopus) ventures forth from the w r oods 
for a little distance. 
There is also a succession, possibly not so definite as this, 
of the swamp birds. So open and wind-swept is the swamp 
in winter that there is but little evidence of bird life, except 
for an Occasional song sparrow in some sheltered thicket, the 
call of a flock of chickadees, or the passing of a rough-legged 
hawk. With the early spring comes the marsh hawk feeding 
upon the voles, and this bird is closely followed by the short- 
eared owl. With warmer weather and the resulting thaw r come 
the swarm of swamp-loving species, together with the retreat 
of the chickadees, who seek the quiet of the woods during the 
summer months and the nesting season. This question of 
avian succession will be discussed more fully in a later paragraph. 
Owing to the diversity of the swamp, it is necessary to divide 
the association into two perfectly natural societies, each of which 
has its own characteristic biota. 
1. The Spartina, or Marsh-grass Society. This society is 
a very large one in every way, and far out-numbers the next 
society of the limniotic association in the number of species 
inhabiting it. The flora consists mainly of the swamp grass 
{Spartina sp.), together with occasional clumps and areas of 
the plume-grass Sorghastrum nutans. The ground is more or 
less under water in the early spring, and great numbers of Lim- 
naea stagnalis and Planorhis campanulatus are to be found after 
the water has retreated. The most abundant crustacean is 
Cambarus argillicola, though in the drier places of the society 
Camharus diogenes is to be found. Here we find also the musk- 
rat, weasel, mink, and meadow vole, their distribution varying 
