Northern Prairie Wildlife Research Center
Northwest Experiment Station, University of Minnesota, Crookston, MN 56716; Minnesota Department of Natural Resources, Crookston, MN 56716; Minnesota Department of Natural Resources, Crookston, MN 56716
In 1988, a multi-purpose flood control project containing uplands, a restored marsh, and a flood storage impoundment was completed in northwest Minnesota. It was a cooperative project of the Soil Conservation Service, Red Lake Watershed District, West Polk Soil and Water Conservation District, and the Minnesota Department of Natural Resources. This study was carried out during 1990-91 to: (1) develop a biological and water quality inventory, (2) evaluate use by migratory and breeding birds, (3) contribute to the development of a long-term management plan, and (4) evaluate project design features from a wildlife perspective. The total project area was about 176 ha with the flood pool and wildlife pool (restored marsh) each about 41 ha. The primary water supply was a county ditch draining a 2,098-ha watershed of which about 95% was in annual crops. Approximate values of water quality parameters in inflow and pool waters were: pH = 9.0, total alkalinity = 200 mg/l, specific conductance = 500 µS/cm, total dissolved solids = 350 mg/l, nitrate = 0.05 mg/l and phosphate = 0.10 mg/l. About half the flood pool was less than 1 m deep when vegetation was sampled in August of 1990, and these areas were dominated by grassleaf (Potamogeton pusillus), leafy (P. foliosus) and sago (P. pectinatus) pondweed. Shorelines were being colonized by softstem bulrush (Scirpus validus) and water plantain (Alisma triviale). The original vegetation of the restored wetland was largely intact and dominated by hardstem bulrush (S. acutus), followed by cattail (Typha spp.), reed (Phragmites communis), and whitetop (Scolochloa festucacea). Cattail was expanding in the wildlife pool because of historically high water levels and possibly a decrease in salinity from freshwater inflows. Invertebrates were inventoried in late May (waterfowl nesting season) and mid-July (brood season) with net sweeps, activity traps, and benthic cores. The wildlife pool generally had greater amounts and types of invertebrates than the flood pool. Water fleas (Daphnia spp). and fingernail clams (Sphaeriidae) were found only in the wildlife pool and scuds (Hyallela spp.) were found only in the flood pool. Midges (Chironomidae) were the most abundant invertebrates in both pools. A minimum of 137 bird species was observed with 60 species nesting, including the following species of "special concern" status in Minnesota: American bittern (Botaurus lentiginosus), greater prairie-chicken (Tympanuchus cupido), sandhill crane (Grus canadensis), upland sandpiper (Bartramia longicauda), Wilson's phalarope (Phalaropus tricolor), sharp-tailed sparrow (Ammodramus caudacutus), and black tern (Chlidonias niger). The study area was a major spring and fall stopover for migrating waterfowl and sandhill cranes and the bare shorelines of the flood pool were attractive habitat for migrating shorebirds. Nesting success of larger birds (waterfowl, coots, bitterns, rails, grebes) was evaluated and about one third of overwater nests hatched each year compared to 1 of 12 (8.3%) upland nests in 1990 and 19 of 31 (61.3%) in 1991. The presence of coyotes (Canis latrans) in 1991 was thought to contribute to higher upland nesting success compared to 1990. The multi-purpose project had significant wildlife values and the following design/management concerns were identified: managing water levels to reduce nest flooding, control vegetation, and expose bare shorelines; maintain vigorous upland vegetation for nesting cover; reduce mammalian predator denning sites; and reduce the expansion of a cattail monotype in the restored wetland.