Wood Ducks 8 3 



count data were analyzed by Chi-square tests to detect differences among wet- 

 lands. 



RESULTS AND DISCUSSION 



Dissolved oxygen was low at all three sites, averaging 2.0 - 2.1 ppm 

 with a range of 0.4 - 6.6 ppm. Acidity was similar among impoundments, aver- 

 aging 5.1 - 5.4 with a range from 4.1 - 6.1. Secchi disc readings also were sim- 

 ilar with a range from 0.18 - 0.93 m. 



Water control structures in 1-1 and 1-3 remained closed throughout the 

 two years of this study, while 1-2 was partly drained half-way through the second 

 year. Density of living upland vegetation within each impoundment diminished 

 with time after flooding, whereas the density of aquatic plants increased (Table 

 1). Most woody vegetation at 1-1 remained vigorous during the first year of 

 inundation, but after two years more than 55% had died. Duckweeds and blad- 

 derwort first appeared during the summer of 1991 and covered approximately 50 

 % of the water's surface by the following summer. Aquatic emergent vegetation, 

 including cattail (Typha latifolia), common rush (Juncus effusus), arrowhead 

 (Sagitarria latifolia), and swamp loosestrife (Decodon verticillatus), was pio- 

 neering along the perimeter of 1-1 by the second summer of inundation (Table 1). 

 About 75% of woody vegetation at 1-2 was dead by the end of the first growing 

 season; 90% was dead a year later. Duckweeds and bladderwort quickly colo- 

 nized 1-2 and covered more than 40% of the surface one year after inundation 

 (Table 1). Downed timber and dying, woody, emergent vegetation at 1-2 provid- 

 ed conditions generally favored by wood ducks and their broods in the southern 

 United States (see Cottrell et al. 1990). However, favorable conditions declined 

 after two years of inundation, as woody cover died and disappeared rapidly cre- 

 ating a more open impoundment. 



A lack of inundated woody vegetation at 1-3 resulted in an open pond, 

 except for one wooded cove and vegetation bordering the stream that fed the 

 impoundment. Some perimeter vegetation was inundated when the water-control 

 structure was closed. Plant mortality in 1-3 thus occurred primarily in the wood- 

 ed coves, which covered only 0.14 ha. Aquatic vegetation present at 1-3 con- 

 sisted primarily of bladderwort and duckweeds. Cattail was growing along the 

 perimeter of 1-3 by the end of the second growing season, and floating organic 

 muck supported thick patches of swamp loosestrife. Swamp loosestrife, giant 

 cane (Arundinaria gigantea), and fetterbush within and along the wooded coves 

 offered cover for wood ducks as they foraged on water oak acorns. 



Mast production varied greatly among impoundments. In the uplands 

 adjacent to the impoundments, more mast was collected at 1-1 (158.7 g, of which 

 southern red oak acorns contributed 148.5 g) than 1-2 (52.2 g) or 1-3 (68.7 g). 

 Mast collected in baskets within the impoundments probably better represents 

 availability in terms of food for wood ducks. However, wood ducks were 



