PRAIRIE MARSH WREN 251 



ferred. The nests are usually placed 1 to 3 feet above water, seldom 

 higher, and are securely fastened to two or more stems of the cattails. 



Nests are less often placed in bulrushes (Scirpiis), sedges (Carex), 

 wildrice {Zizania) , tall marsh grasses, or even small bushes. In North 

 Dakota we found these wrens nesting around the edges of the sloughs 

 in either dead or green cattails, or in the bulrushes. Near Lake Win- 

 nipegosis, Manitoba, we found a nest firmly attached to the canes of 

 bulrushes, 4 feet above the water ; it was within 4 feet of a canvasback's 

 nest and was lined with down from the nest of the duck. The nest is 

 said to be shaped like a coconut, or globular, but some that I have seen 

 have been egg-shaped with the pointed end at the bottom. The en- 

 trance is a small round hole, usually near the top. 



Dr. Welter (1935) gives an elaborate account of the building of the 

 brood nest, which is done almost entirely by the female, and which 

 requires 5 to 8 days, beginning 6 to 15 days after her arrival. He 

 writes : 



The initial effort in building consists of lashing the supporting plants to- 

 gether and in this way form a cup-like foundation upon which the remainder of 

 the nest rests. Carex and Calamagrostis are the chief materials used in this part 

 of the structure. The outer walls which are composed for the most part of long 

 strips of cattail leaves and stems and leaves of sedges and grasses is the roughest 

 part of the structure. Water-soaked materials, often more than a foot long, are 

 used here as they are more pliable and can more easily be woven together. The 

 first strands are woven around the long axis and others, as the nest assumes 

 shape, are put in at various angles. Some of these strands are fastened to the 

 supporting structure by actually weaving these stems into the nest. Some of 

 the growing leaves are also woven into the outer walls. If the support is a sedge 

 or a grass, leaves may form a good share of the periphery. An opening is left on 

 one side about two-thirds of the distance from the bottom of the nest. At this 

 stage a dummy would be complete. The walls average at least a half inch in 

 thickness and the external measurements of the entire structure approximate 

 seven and five inches for the vertical and horizontal diameters, respectively. 

 Inner diameters average five and three inches. 



The outer shell is a small part of the completed structure, and only 2 days are 

 required to build it. The remainder of the work is done from the inside and one 

 must take a nest to pieces to get an idea of its arrangement. Grass and sedge 

 leaves and small stems are used to form the second layer. This gives the walls 

 firmness and tends to fill in the large air spaces which are necessarily present 

 among the coarse materials of the outer walls. 



The nest layer to be added seems to function as an insulating region. Cat-tail 

 down, feathers, small unidentified rootlets, entire plants of Lemna, and decayed 

 fragments of Typha and Carex are the materials most often used. These are also 

 placed into the structure in a wet condition so that, when dry, they form a compact 

 and tight-fitting region which serves as a non-conductor of heat, cold, and moisture. 



The innermost region is composed of finely shredded pieces of the vascular 

 materials of the plants forming the outer layers. A large proportion of it is 

 very fine strips of sedges and grasses of the preceding year. Feathers of almost 

 any available sort are used here. Those from the following birds have been identi- 

 fied: Red-winged Blackbird, Virginia Rail, American Bittern, Pheasant, Ruffed 

 Grouse, and domestic chicken. The projection at the opening is a part of this in- 



