Dabbling Duck Response to a Late-winter Variation in Saltmarsh Bulrush Management

Late winter dabbling duck use of experimentally manipulated saltmarsh bulrush (Scirpus robustus) was evaluated in managed brackish wetlands in the Santee River Delta, South Carolina, during 3-21 February 1989. Three 1-ha plots were established in each of 3 treatments: saltmarsh bulrush that was dewatered, burned, and reflooded (burned, flooded bulrush [BFB]); saltmarsh bulrush that was dewatered and then reflooded (unburned, flooded bulrush [UFB]); and low stemdensity saltmarsh bulrush that was flooded throughout winter (winter-flooded bulrush [WFB]). Species and numbers of dabbling ducks using treatments were identified and counted. Densities of dabbling ducks using BFB (x¯ = 100 ± 25.60 [SE], N = 12) and WFB (x¯ = 65 ± 8.28, N = 12) were similar (P > 0.05); densities of dabbling ducks using UFB (x¯ = 5 ± 1.82, N = 12) were significantly lower (P < 0.05) than for the other treatments. Dabbling ducks species richness (N = 8) in BFB and WFB was equal, whereas UFB attracted only 3 species. Northern pintails (Anas acuta) were most abundant and dominated counts of WFB and BFB on most days, comprising 64% and 75% of the ducks counted, respectively. Mallards (A. platyrhynchos) and black ducks (A. rubripes) were the most numerous species using UFB and constituted 96% of the ducks counted. Burning created openings in dense saltmarsh bulrush that typically received low use by waterfowl. Thus, a previously little-used habitat was converted into 1 used readily by dabbling ducks.

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