 The nest is made from whatever wetland vegetation is available and built mostly by the male , usually in a single day . It is raised 15 cm ( 5 @.@ 9 in ) or more above the level of the marsh , and is sometimes constructed on clumps of roots , tree stumps or similar support . It may be built up higher if the marsh waters start to rise . The nest is 13 – 16 cm ( 5 @.@ 1 – 6 @.@ 3 in ) across and about 7 cm ( 2 @.@ 8 in ) high . It is well hidden and approached cautiously by narrow tracks . 
