Important Bird Areas

Mississippi River Twin Cities IBA

Minnesota

This Important Bird Area includes the Mississippi River and its adjacent floodplain forest and uplands extending 38 river miles through four Minnesota counties from Minneapolis to Hastings, Minnesota. The upstream extent is the Washington Avenue bridge in Minneapolis at approximately river mile 852. Downstream its extends through the ?Twin Cities? of Minneapolis and St. Paul, as well as encompassing contiguous portions of three townships and ten other riverfront communities along the main river channel to the Highway 61 bridge at river mile 814 at Hastings, MN. The entire portion of the Mississippi River known as Pool 2, which occurs between Lock & Dam 1 (at Minneapolis) and Lock & Dam 2 (at Hastings) is included, as are the lower portion of Pool 1 and the very upper end of Pool 3.

For the most part, the other boundaries of this Important Bird Area are congruent with the boundary of the Mississippi National River and Recreation Area (MNRRA - a unit of the National Park Service) between river miles 852 to 814. Slight adjustments to the MNRA boundary were made to include bird habitat at Battle Creek Park Reserve and Fish Creek Park in Ramsey Co.

This Important Bird Area occurs within the most densely populated and highly urbanized portion of Minnesota. Included are 37,091 acres of lands and water. The aquatic portion of the area encompasses 10,847 acres or 30.5% of the IBA. The aquatic habitats consist predominately of the open waters of the main river channel (9,304 acres of river/stream or 26.3 %) , riverine lakes (1,291 acres or 3.5%) and open water wetlands (252 acres or 0.7 %) all of which are without emergent vegetation. Within the scheme of the Minnesota Land Cover Classification System (MLCCS), wetlands with emergent vegetation are classified as herbaceous cover types and not included in these calculations of the aquatic portion of the IBA. Therefore, they are considered in the terrestrial habitats discussed below.

Nearly one third of the IBA (11,155 acres or 30.6%) has been classified as Cultural cover types (that is, ?man influenced cover types where artificial surfaces or planted and cultivated vegetation occur over >4% of an area?). This man-dominated landscape has been categorized as urban residential/industrial/transport (and mining)) for purposes of this nomination and acreage calculations and is considered both a cover type and a land use.

The remaining approximately 1/3 of the IBA (@ 13,700 acres) is composed of the 12 cover types situated on lands where photo-interpretation indicates that the land cover is >96% natural vegetation as characterized by the MLCCS (MN DNR 2000). These acres might be considered ? undeveloped? lands.

There is a great potential for acquisition, protection, restoration and management to provide habitat for birds within the terrestrial portions of this IBA including the urban residential/ industrial/transportation/mining component, as well as the on the undeveloped acres. Indeed, a recent report entitled, ?Open Space Protection Opportunities Guidebook for the Mississippi National River and Recreation Area?, identified 20,000 acres within the more extensive 72 mile MNRRA corridor as Open Space Protection Opportunities (OSPO). Open space is defined by this plan as ?public or private land that is retained as primarily undeveloped. This could include lands devoted to active or passive recreation, or lands retained for visual or natural resource protection purposes?. At a minimum and within the IBA, these OSPO include 3 regional park reserves of at least 1000 acres each, 2 county parks, 3 state-owned Scientific and Natural Areas, a number of city parks, and 2 small, private nature reserves currently managed for their natural attributes.

Ornithological Summary

This IBA is situated along the Mississippi Flyway, the migratory corridor for 40% of North America?s waterfowl and shorebirds. Specifically, it is a part of a waterfowl flight corridor defined by Belrose as the Mid-Minnesota Corridor. This corridor extends from eastern Manitoba to the upper Mississippi River south of Minneapolis, presumably including Pool 2 of the Mississippi River. An estimated 760,000 dabbling ducks (wood duck, teal and widgeon) including 600,000 mallards, use this corridor according to Belrose.

More recently, and more specifically to this IBA, an unpublished study by Liddell and Cooper estimated migratory waterbird abundance and species composition for Pool 2 of the Mississippi River during the spring, summer, and fall of l997. For purposes of their study, waterbirds included loons, cormorants, gulls, terns, ducks, geese, swans, herons, egrets, pelicans, coots, grebes, and other miscellaneous species. Aerial surveys and ground counts were conducted. Another bird survey effort was conducted by Bardon over a total of 30 days of coverage from 11 March to 25 April, 2001. He counted spring migrants moving up the Mississippi River past the confluence of the Mississippi and St. Croix Rivers in the vicinity of Hastings, MN and Prescott, WI at the southern extent of this IBA. Although over half a dozen different observations sites were used during the course of his monitoring, all sites occurred within one mile of each other site. This survey was concluded prior to the end of migration for raptors, gulls, terns and various passerines. However, he has previously reported on gulls moving through the Twin Cities area during spring migration.

Liddell and Cooper reported an estimated 36,493 waterbirds used Pool 2 in the spring of l997. Waterfowl (mainly diving ducks and Canada geese) and gulls (mostly Ring-billed Gulls) were the most abundant species groups observed during spring surveys. An average of 57.2% of waterbirds counted during the spring population surveys were waterfowl (ducks, geese, and swans), 30.7% were gulls and terns, 7.9% were cormorants and pelicans, 2.4% were egrets and herons, 0.8% were coots and grebes, and 0.9% were other waterbirds (eagles, loons, shorebirds and kingfishers). Six Minnesota threatened and special concern species were seen at ground survey sites during the l997 spring surveys including: Horned Grebe, American White Pelican, Common Tern and/or Forster?s Tern, Franklin?s Gull and Bald Eagle. Several other species of interest, such as Black Tern, American Redhead, Canvasback, and scaup ducks, were also observed during spring migration.

Bardon observed 75,584 waterbirds (loons, grebes, pelicans, cormorants, herons, egrets, cranes, tern, gulls, ducks, geese, swans, and sandpipers) during spring migration at observation sites just downstream of the IBA boundary. He estimated that a majority of the waterbird flight occurred within Minnesota and that most of the waterfowl continued to move up the main channel of the Mississippi River from his observation points and into Pool 2 and the main river lakes within the IBA.

Bardon has also documented gull activity in the vicinity of the Twin Cities including know roosting locations within the IBA at Pig?s Eye Lake and Spring Lake with noteworthy numbers (2,000) of Bonaparte?s Gulls noted in the Lower Grey Cloud Island area in April /May l995.

A total of 3,725 waterbirds were counted by Liddell in Pool 2 during biweekly summer aerial surveys. Gulls were the most abundant species observed (59.9 %), followed by waterfowl (13.8%), cormorants and pelicans (13%), egrets and herons (12.8%) and 0.5% other waterbirds (eagles and shorebirds).

Information on file with the MN DNR Natural Heritage database indicates that one mixed species heron rookery totaling @1600+ nesting pairs of 4 species (including 80 nests of Black-crowned Night Herons), 8 Bald Eagle breeding territories and nest sites for 6-8 pairs of Peregrine Falcons are known to occur with the IBA.

In the Liddell study, the Pool 2 fall waterbird population was three times greater than spring and summer, with an estimated 126,071 waterbirds using the area between August 31 and December 23. The fall waterbird population was comprised mostly of gulls and cormorants through mid-October, thereafter most of the birds were waterfowl (primarily Mallards and Canada geese). Interviews with waterfowl hunters and local bird watchers, along with ancillary data suggested that the l997 fall waterfowl numbers were well below normal due perhaps to unseasonably warm weather and abundant surface water on the prairies to the west.

D Zumeta has recorded 157 species of birds in the Mississippi River Gorge Area at the upstream end of the IBA. He indicates that 51 species are confirmed or likely breeding species. T. Bell reports 207 species observed since l965 at the Lower Grey Cloud Island area near the downstream end of the IBA.

Conservation Issues

As use of the river and adjacent lands grows, there is increasing potential for conflicts between uses. Some examples that particularly impinge on the habitat values of the lands and waters within the IBA include:
Barge transportation and fleeting as well as recreational boating can cause impacts to wildlife habitat.
Maintaining navigation improvements, such as the 9-foot channel, requires periodic dredging and a need for dredge disposal sites.
Remaining areas of bird habitat could be adversely affected by extensive development.
Sand and gravel mining in the lower reaches of the IBA have to potential to considerably alter aquatic and/or terrestrial habitats.
Native vegetation along the shoreline, in wetlands, and along the bluffs is important to ecological functions of the remaining natural systems. Curtailment of natural disturbance factors ( such as fire) and invasion by exotic species of plants and animals ( including feral dogs and cats) is particularly acute.
Significant improvements have been made in wastewater treatment in the Twin Cities area. However, water quality is still a major concern. Issues range from toxic wastes to sedimentation to endocrine disrupting chemical contamination.
Direct loss of habitat, especially aquatic habitat, has occurred because of competing interests and uses such as recreation and commercial development. Direct and indirect loss of wetlands has been due to ground water depletion, storm water runoff and water diversion from wet areas.
Considerable public land already exists, but the amount and distribution of open space needed to protect the river's resources and to provide for the area?s many competing uses, including wildlife habitat, continues to be a major issue.

Ownership

A wide variety of ownership types exist within this IBA. As a river corridor through the Twin Cities metro area most of the surrounding land is urban with the usual mix of private and public ownership. The IBA follows the National Park Service Mississippi National River and Recration Area boundaries. Much of the best bird habitat is found in County and City parks or State owned Scientific and Natural Areas.

Habitat

This Important Bird Area occurs within the most densely populated and highly urbanized portion of Minnesota. Included are 37,091 acres of lands and water. The aquatic portion of the area encompasses 10,847 acres or 30.5% of the IBA. The aquatic habitats consist predominately of the open waters of the main river channel, riverine lakes and open water wetlands all of which are without emergent vegetation. Nearly one third of the IBA has been classified as Cultural cover types (that is, ?man influenced cover types where artificial surfaces or planted and cultivated vegetation occur over >4% of an area?). This man-dominated landscape has been categorized as urban for purposes of this nomination and acreage calculations and is considered both a cover type and a land.

The remaining approximately 1/3 of the IBA (@ 13,700 acres) is composed of the following 12 cover types situated on lands where photo-interpretation indicates that the land cover is >96% natural. These acres might be considered ? undeveloped? lands.

Upland deciduous forest (maple-basswood, oak, aspen, northern hardwoods) 14.2%; Lowland deciduous forest (includes floodplain forest, ash swamp) 8.32%;Upland mixed deciduous/conifer forest <1%; Lowland ( wet ) native prairie <1%; Wet meadows (broad-leaved sedges); Marsh ( cattail/mixed emergent) 1.2%; Upland native prairie ( includes dry, mesic, and brush prairie) 3.3%; Upland savanna ( includes jack pine savanna, oak savanna, and aspen openings) 2.9%; Grassland ( non-native planted) 2.7%; Agriculture 4.2%; Cliff/talus <1%; Woodlands ( <60% canopy closure) included in upland deciduous