Waterbird Use of Open Marsh Water Management Ponds in Maryland

During autumn 1985, we investigated waterbird use of Open Marsh Water Management (OMWM) ponds and use of natural ponds in an adjacent impoundment in Maryland. Dabbling ducks used ponds with dense widgeongrass (Ruppia maritima) more than ponds with sparse or no widgeongrass (P <0.01). Wading birds and shorebirds used the natural ponds more than the OMWM ponds (P <0.01), mainly because the OMWM ponds had vertical sides and were too deep (¯x = 0.42 m) to allow foraging. Pond surface areas were positively correlated with numbers of birds (P <0.05) and inversely correlated with densities of birds (P <0.01).