Important Bird Areas

St. Louis River Estuary

Minnesota

The St. Louis River Estuary is a freshwater ecosystem that is one of the largest tributaries draining into the largest, by surface area, lake in the world ? Lake Superior. The ecosystem is an extensive riverine system with numerous bays, wetlands, and forested areas in its adjacent shoreline. The area is highly industrialized, and residential areas are numerous along its shoreline. Many of the industrialized areas have been abandoned and are in need of major restoration efforts. The area receives extensive use for shipping of ores, grain, and other containerized commodities, especially in its eastern end.

The upper reaches of the estuary are heavily used by fisherman and recreationists such as bird watchers and boaters. The Western Waterfront Trail, maintained by the city of Duluth, runs along its shoreline on the Minnesota side and provides land access to the estuary for recreational activity. The entire estuarine ecosystem represents a contiguous migratory pathway at the extreme western end of Lake Superior. Because migratory birds tend not to cross large bodies of water, like Lake Superior, both spring and fall migratory birds are funneled into the estuary.

The bay-mouth bar at the entrance to the estuary, Minnesota Point and the adjacent Wisconsin Point, is labeled as the longest fresh-water barrier beach in the world (7 miles in Minnesota and 3 miles in Wisconsin). The beach and dune system are unique in Minnesota and contain several rare natural plant communities that have been described by the Minn. DNR County Biological Survey: beachgrass dune, juniper dune shrubland, sand beach, and beach ridge shrubland. Several rare plant species occur there as well: false heather, beach pea, sand cherry, beach grass, pale moonwort. Part of the natural old-growth pine forest at the southern end of this sand bar has been designated by the Minn. DNR (in 2002) as Minnesota Point Pine Forest SNA (118 acres with 18 owned by the DNR). The Superior Water, Light & Power Co. owns land in the middle of the pine forest for their pumping station and donated an easement on 17.5 acres to the Minnesota Land Trust in 1998. The Army Corps of Engineers owns 51 acres at the end of the point adjacent to the Superior entry; it is mostly barren disturbed land and shrubby young forest. Between the Recreation Center at the south end of the access road (Minnesota Ave.) and the Pine Forest is the Sky Harbor recreational airport (33 acres) controlled by the Duluth Airport Authority. All in all, about 65 % of Minnesota Point (584 acres total) is parkland or open space.

The St. Louis River Estuary in association with adjacent Minnesota Point is among the best and most popular sites for bird watching in Minnesota. The well-known birding locations in the Estuary include the Port Terminal, Interstate Island, Erie Pier and 40th Avenue West, mouth of Miller Creek, West Skyline Parkway below Enger Park (spring raptor migration), Indian Point Campground, Western Waterfront Trail, Spirit Lake, Mud Lake, Morgan Park, Oliver Bridge area and WWJC radio tower area, Boy Scout Landing, Perch Lake, and Chambers Grove in the community of Fond du Lac. The wetlands and associated shrub habitats of the area include breeding populations of Sedge Wren, Marsh Wren, Alder Flycatcher, Sora, Virginia Rail, Swamp Sparrow, Chestnut-sided Warbler, and Yellow Warbler. It is possible to see Green Heron and American Bittern as well, besides many migrant waterfowl species.

On Minnesota Point all the public accesses on the lake side offer a view of the big lake and the beach with opportunities for observing, photographing and counting waterfowl, waterbirds and shorebirds. The most used are Franklin Park (at S. 10th St.) and Lafayette Square (at S. 30th St.). Along the harbor side of the Point, there is birding access at 19th Street near Hearding Island, at the Rowing Club and Southworth Marsh. The Recreation Area at the end of the road is a great place to find migrant land birds as well as shorebirds on the grassy ball field. It also offers great views of the lake, beach and bay. The old-growth pine forest beyond the road can be accessed by a nature trail; the woods contain at least 16 breeding northern forest species; the most unique for this area is Pine Warbler.

Ornithological Summary

Over the years birding activity in the estuary and along Minnesota Point has produced a great deal of information about bird migration, its seasonal timing, abundance and habitat use.

Significant concentrations ? waterbirds. - Herring Gulls breed sparingly in the estuary but occur during spring migration in large numbers (peak of 8,000 on 5/8/10) and also over winter in a flock that can number 1,000-2,000 birds. A breeding colony of Ring-billed Gulls on Interstate Island numbers from 13,500 to 8,734 pairs. Large flocks (1,000-4,000 birds) of Bonaparte?s Gulls are sometimes found off Minnesota Point in the spring. Common Loons in spring can peak at 100-200 birds/day on Lake Superior, with seasonal counts of 1,179. Red-throated Loon high counts of 102-117 birds have been made in spring. American White Pelican spring migration has increased markedly in recent years; with counts of 1,066 in 2009 and 972 in 2010. Common Terns breed in the estuary but also occur as large flocks in the spring; peak numbers are 1000-1500 birds.

Significant migratory raptor corridor. - Spring migration mean yearly count is 23,296. Species with a significant high yearly mean are: Turkey Vulture ? 1,426, Osprey ? 186, Bald Eagle ? 3,120 (Significant yearly high ? 4,142 in 2009; peak day 822 on 3/23/04; other peak days of 200-600 birds are not unusual; these spring counts rate as some of the highest in the U. S), Sharp-shinned Hawk ? 2,275, Broad-winged Hawk ? 10,961, Red-tailed Hawk ? 4,806, Golden Eagle ? 71.

Exceptional diversity of bird species - The total number of species that regularly use the IBA is 238. This is 76% of the 314 species that are found somewhere in Minnesota every year. Most of these species are migrants. Only 74 species are documented or presumed to be breeding in this IBA.

Waterfowl - There are 31 species of waterfowl that regularly use the IBA during migration. Greater Scaup are found in the spring with high counts of 3,000 ? 5,000 birds. Because they are mixed with Lesser Scaup and are often so far out in the lake, accurate separation of species is not possible so the number may be much larger. Counts of Lesser Scaup are 1,000-2,000 birds and the caveat on species separation applies as well. Common Goldeneye wintering congregations are 350-550 birds. Early spring numbers are also large, reaching 500-600 birds. Although their numbers are not large all three scoters are found in the IBA.

Shorebirds - There are 27 species of shorebirds that use the IBA regularly during migration in small (but significant for this BCR) numbers. Several are of special interest, however; Buff-breasted Sandpipers, Piping Plover and Red Knot have been found in recent years.

Gulls - Herring Gull and Ring-billed Gull are the abundant gulls in the IBA and Bonaparte?s and Franklin?s Gulls are regular during migration. Thirteen other gull species are found in the IBA including; Black-legged Kittiwake, Ivory Gull, Little Gull, Mew Gull, California Gull, Slaty-backed Gull, and Glaucous-winged Gull. Both Sabine?s Gull and Lesser Black-backed Gull are regular migrants. Over wintering gulls, besides Herring Gull, are Thayer?s Gull, Iceland Gull, Great Black-backed Gull and Glaucous Gull.

Passerines - During inclement weather, usually foggy or drizzly conditions, large fallouts of warblers and other boreal forest birds are encountered. These conditions occur almost yearly at least once. At these times daily counts of warblers can number 20-25 species. The most abundant warbler species are Tennessee, Nashville, Yellow, Chestnut-sided, Magnolia, Cape May, Yellow-rumped, Palm, Blackpoll, American Redstart, and Wilson?s. Other land birds with high daily counts include Yellow-bellied Sapsucker, Red-eyed Vireo, Golden-crowned Kinglet, Swainson?s Thrush, Hermit Thrush, swallows, Blue Jay (4604 in 2010) and American Robin (9803 in 2009).

Significant number of a particular species - In winter typically 2-4 and up to 8-15 Snowy Owls can be found wintering in the Duluth-Superior harbor. Highest number of owls recorded was 31 in the winter of 1996-1997.

Sites for species of conservation concern - Horned Grebe is an abundant migrant in the spring at Minnesota Point; 100-1000 birds can be counted in a single day. Recent high count was 2,416 on 4/23/10. Two pairs of Peregrine Falcons nest in the IBA. Common Tern numbers have fluctuated from a low of 68 nests (1986) to a high of 264 nests (1995). For the last ten years the number of nests has been fairly steady from 166 to 238 (average 194). At this time there are two Bald Eagle nests in the estuary.

Conservation Issues

Threats to the IBA include:
loss of habitat due to urban development
loss of habitat due to expansion of the Sky Harbor Airport
recreation management and use of beach and dunes
contamination from commercial shipping
increased sedimentation from development
increased salination of the watershed
forest management practices
introduction of exotic species
abandonment of industrial contaminated sites
contamination from industrial activity

Wetland complexes within the IBA face an array of conservation threats, including industrial development, residential development, and recreational development. The primary threats to the forested habitats in the IBA are residential development, recreation management and urbanization. The reduction of patch size favors species that are edge specialists such as the nest-parasitic Brown-headed Cowbird, further stressing forest species with no natural defense against the new threats. The open sand beaches provide vital nesting, feeding and loafing habitat for a variety of shorebirds and larids. Increased housing development and recreation use of the beach and dunes threatens this vital beach habitat. Additionally, the old-growth pine forest at the southern end of the Point is continually threatened by expansion and intensity of use of the Sky Harbor Airport . Unapproved camping and bonfires on the Point are also a risk to habitat and resting species, as are dogs off leash all along the Point.
Construction of dredge islands in the IBA temporarily provided suitable nesting habitat for species such as the Piping Plover and Common Tern, though the former is now extirpated. A concern is the lack of continued habitat management of the two Wildlife Management Areas that were created for barren-land breeding sites for these species. The continued protection of these critical habitats is integral for the hopeful return of the Piping Plover, but long-term funding for management has proven unavailable.

Ownership

The Superior Water, Light & Power Co. owns land in the middle of the pine forest for their pumping station and donated an easement on 17.5 acres to the Minnesota Land Trust in 1998. The Army Corps of Engineers owns 51 acres at the end of the point adjacent to the Superior entry; it is mostly barren disturbed land and shrubby young forest. Between the Recreation Center at the south end of the access road (Minnesota Ave.) and the Pine Forest is the Sky Harbor recreational airport (33 acres) controlled by the Duluth Airport Authority. All in all, about 65 % of Minnesota Point (584 acres total) is parkland or open space.

Habitat

The bay-mouth bar at the entrance to the estuary, Minnesota Point and the adjacent Wisconsin Point, is labeled as the longest fresh-water barrier beach in the world (7 miles in Minnesota and 3 miles in Wisconsin). The beach and dune system are unique in Minnesota and contain several rare natural plant communities that have been described by the Minn. DNR County Biological Survey: beachgrass dune, juniper dune shrubland, sand beach, and beach ridge shrubland. Several rare plant species occur there as well: false heather, beach pea, sand cherry, beach grass, pale moonwort. Part of the natural old-growth pine forest at the southern end of this sand bar has been designated by the Minn. DNR (in 2002) as Minnesota Point Pine Forest SNA (118 acres with 18 owned by the DNR).