Waterbird use of high saltmarsh ponds created for open marsh water management (mosquito control)

The excavation of small (<0.2 ha) ponds and ditches in high-marsh mosquito breeding areas has evolved into an integrated public health-wildlife program known as Open Marsh Water Management (OMWM). Originating in New Jersey in the 1950s, the practice has now expanded to New England south to North Carolina and Florida. Much more assessment is required to determine the impacts of such alterations on the marsh ecosystem. A study was begun in 1986 to assess waterbird use of OMWM ponds and natural (control) ponds in New Jersey, Delaware, and Maryland. Intensive observations of ponds from elevated blinds were conducted weekly (Bombay Hook NWR, Delaware) or biweekly (Forsythe NWR, New Jersey) from May until mid-November. Early morning and later afternoon observation periods were scheduled to sample 3 tide levels (low, high, mid). In addition, aerial surveys were conducted during fall-winter at 8 locations in coastal Maryland (3), Delaware (3), and New Jersey (2). Preliminary results suggest that the use of OMWM ponds was very limited by any of the waterbird groups. The major of birds used either very large (>1 ha) natural ponds or pannes or adjacent tidal creeks. Recent modifications in pond construction in Delaware and New Jersey allow for shallower, more sloping basins which should enhance use by waterfowl and shorebirds while still ensuring a water reservoir to support fish populations.