65 



IV. The Sedge Association. 

 (Plate VI, fig. 1.) 



Here, as the name implies, the predominant forms of vegeta- 

 tion are the sedges. Several species occur, of which the most 

 abundant is Sdrpus fluviatilis. This Association is nearly 

 as pure as that of the cat-tails, and occupies areas nearly as 

 extensive. In some places within the zone, such as the edges 

 of ponds, the sedges are not firmly estabUshed, and numerous 

 aquatic or semi-aquatic plants flourish. Many of those which 

 make up the shore-hne association are thus found scattered 

 through the sedges. The rate of growth of Scirpus fluviatilis j 

 determined as for the cat-tail at four stations, between May 6 

 and June 21, 1910, averaged slightly over an inch per day 

 (Fig. 2). Previous to May 6, the growth was slow. It 

 ceased, as in the case of the cat-tail, in the latter part of June 

 or early July, when between 80 and 90 inches in height. 



The birds most typical of this habitat are the American Bit- 

 tern and the Swamp Sparrow, the latter being almost wholly re- 

 stricted to it at the nesting season. The Marsh Wren, like- 

 wise, reaches its greatest abundance here. Of the other birds, 

 the Redwing, the Rails, and occasionally the Coot and the 

 Florida Gallinule, extend their nesting range from the previous 

 zone into the sedges. The Song Sparrow and the Maryland 

 Yellow-throat, in like manner, extend their range from the 

 grass zone on the other side, and are found nesting with the 

 Swamp Sparrow. 



Among the mammals, the Jumping Mouse (Zapus hud- 

 sonius) probably reaches its maximum numbers in this zone. 

 The Meadow Mouse continues to be very abundant, and the 

 Star-nosed Mole (Condylura cristata) occasionally occurs. 



The question of forage here repeats itself. The seeds of 

 the sedges are occasionally found in the stomachs of the Red- 

 wing and the Rails, but, because of their exceedingly thick 

 seed-coats, are probably used rather as grinding stones. The 

 society is rich in insect Ufe, however, and furnishes much of that 

 type of food. The Marsh Hawk (Circus hudsonius), which 

 might be included among the birds of this association, preys 

 upon the Meadow Mice before the sedges become too high. 



