: This technical note describes studies of environmental conditions and habitat quality of replicated pond ecosystems dominated by populations of exotic plants or mixed communities of native aquatic plants. Study ponds were similar in depth, size, and shape, as well as in (initial) water and sediment composition. One component of these studies included evaluation of migratory waterfowl utilization of pond habitats based upon vegetation community composition. Aquatic vegetation is a critical food source for many migratory waterfowl, and numerous studies have shown that water bodies with abundant aquatic plants receive the greatest use (White and Malaher 1964, Hobaugh and Teer 1981, Johnson and Montalbano 1989). In cases where aquatic vegetation is restricted or absent, waterfowl use is generally low (Heitmeyer and Vohs 1984). Additionally, declines in migratory waterfowl have been correlated with loss of submersed aquatic vegetation in numerous water bodies (Jorde et al. 1995, Orth and Moore 1981, Haramis 1991). The benefits of aquatic vegetation for waterfowl may be dependent upon the species of vegetation present, with studies showing that migratory waterfowl appear to prefer native aquatic plants as opposed to exotic species (Smith 2001, Benedict and Hepp 1996). Although reasons for this preference are not clear, native plants are held to be more nutritious than exotic species and are therefore%more valuable to waterfowl (Paulus 1982, Sudgen 1973). Native aquatic plants may also provide better habitat for invertebrate recruitment, an important supplemental food source for many waterfowl species (Keast 1984). Conversely, invasion and establishment of less beneficial exotic aquatic plants such as hydrilla (Hydrilla verticillata) and Eurasian watermilfoil (Myrlophyllum spicatum) may limit waterfowl utilization of water resources.

Assessment of aquatic plant selection by waterfowl has been conducted during the winters of 1997-2000 on 49 0.2-0.79 ha research ponds in north central Texas. Ponds were categorized by dominant plant species into eight habitat types. Census with waterfowl species identification were performed to investigate impacts of aquatic vegetation and water depth on waterfowl. Eighteen waterfowl species were observed. Peak migration occurred in late December/early January. Mixed native ponds and mixed native/hydrilla ponds were the most frequently selected habitat types. The study included correlation analysis between pond water levels and waterfowl use. Full ponds received greatest use followed by half full ponds, while almost empty ponds received minimal use. Time activity budgets were conducted on waterfowl utilizing mixed native and hydrilla ponds to compare waterfowl time partitioning on native aquatic vegetation versus hydrilla. Although only minor differences were found in time budgets, social status appears to be strongly related to habitat selection. Ducks on native ponds were paired (86%), conversely no ducks on hydrilla ponds were paired. Hydrilla pond although frequently utilized, were populated by lower status birds mostly single hens.