Rare Species Guide

  Basis for Listing

Three North American piping plover populations are recognized: Atlantic Coast, Great Lakes, and northern Great Plains. Human disturbance on nesting grounds, nest predation, and loss of habitat on both breeding and wintering grounds have caused serious declines in all three populations (U.S. Fish and Wildlife Service 1988). A population model suggests that the northern Great Plains population is declining by 7% annually (Ryan et al. 1993). In Minnesota, piping plovers once nested on sparsely vegetated dredge spoil disposal areas in the Duluth Harbor on Lake Superior. This population declined throughout the 1970s and 1980s, and has since been extirpated. A single population of piping plovers still exists in Lake of the Woods County, concentrated on Morris Point, Garden Island, Pine and Curry Island, and the Rocky Point Wildlife Management Area. However, the number of breeding pairs in this population is at a critically low level, with just 0-2 pairs in recent years. The sandy beach habitat used by these piping plovers is vulnerable to fluctuating water levels and erosion, and is also seriously threatened by predation and human disturbance. Despite intensive efforts to protect nests and improve habitat, the plight of the Lake of the Woods population continues.

As of the 2001 International Piping Plover Census, Minnesota's population had declined 46% since 1991 and the northern Great Plains region as a whole had lost 14.9% of its population over the same time period (Ferland and Haig 2002). Through extensive recovery efforts, the Great Lakes piping plover population in Michigan has increased in recent years. Although small numbers of these birds are observed in the Duluth Harbor area, there has been no successful nesting here in over 25 years, and recovery opportunities are limited. The piping plover was designated a state endangered species in Minnesota in 1984. In 1986, piping plovers within the Northern Great Plains population, which includes Lake of the Woods, were listed as federally threatened by the U.S. Fish and Wildlife Service, and piping plovers in the Great Lakes population were listed as federally endangered.

  Description

The piping plover is a small (15-18 cm (6-7 in.)), sand-colored shorebird that is well camouflaged against the sandy beaches it inhabits. Distinctive markings of breeding-plumaged adults include a narrow black band between the eyes, a narrow black breast band, and orange-yellow legs. The similar semipalmated plover (Charadrius semipalmatus), a common migrant, has much darker upperparts, broader black breast band, and more extensive black on the face. Killdeer (Charadrius vociferous) are significantly larger and easily distinguished from piping plovers by their double breast band and vocal behavior.

  Habitat

In Minnesota, the piping plover nests on sandy beaches with areas of gravel or pebble substrate and little or no vegetation. Wide dune systems interspersed with flat cobbled areas are especially favored by piping plovers elsewhere in their range (Haig 1992).

  Biology / Life History

Piping plovers from the Great Lakes and the northern Great Plains populations leave their breeding grounds between late July and early September and overwinter on beaches, sandflats, and dunes along the Gulf and Atlantic coasts. They return to Minnesota from late April through late May (Green and Janssen 1975). Piping plover nests are scraped-out depressions in sandy soil, and they may be lined with pebbles. Spacing between piping plover nests varies, but generally a pair will defend a small territory of about 200 m (656 ft.). Females lay an average of 4 eggs. The eggs are incubated by both sexes, and hatch in 25-28 days. Females leave the nest before the young fledge, but males stay with the young until they are around 27 days old.

Piping plovers and their eggs are camouflaged against the beach, which helps to reduce predation. If an intruder comes near their nest, piping plovers will fake a broken wing to lure the intruder away. If the parents spend too much time away from the nest, the eggs become vulnerable to predation and overheating in the sun. Predators of piping plover eggs include ring-billed gulls (Larus delawarensis), herring gulls (Larus argentatus), great horned owls (Bubo virginianus), American crows (Corvus brachyrhynchos), common ravens (Corvus corax), and mink (Mustela vison) (Cuthbert and Wiens 1982). Fox, dogs, cats, raccoons (Procyon lotor), and skunks will prey on adult and hatchling piping plovers.

Piping plovers eat a variety of aquatic and terrestrial invertebrates. They capture their food by pecking and gleaning along the shoreline in the area between the splash zone and herbaceous vegetation. In substrates with more sand and mud, piping plovers may also vibrate one foot against water-saturated sand to bring invertebrates to the surface (Haig 1992).

  Conservation / Management

Piping plovers are threatened by a variety of factors including predation, fluctuating water levels, weather, habitat degradation and loss, and competition with gulls for nesting areas. Lake of the Woods and Manitoba piping plover populations may also be experiencing problems associated with small population size such as inbreeding depression, which can contribute to reduced reproductive success, population instability, and increased likelihood of local extinction (Maxson and Haws 2000). Gull deterrents and gull egg removal, while labor-intensive, should be employed at piping plover nesting sites to keep gull numbers down. Beaches on which piping plovers are nesting should be closed to human traffic during the breeding season to prevent disturbance to birds and destruction of their nests, and wire mesh exclosures should be placed around nests to prevent nest predation. Additional information is needed about conditions on piping plover wintering grounds, the extent and effects of genetic mixing between the three piping plover populations, and the effects of contaminants at breeding, migration, and overwintering sites.

  Conservation Efforts in Minnesota

Piping plover management efforts in the Duluth area began in 1977 and focused on vegetation removal and predator trapping. These efforts could not prevent the extirpation of this small breeding population, and there has been no successful nesting here in over 25 years. Through intensive recovery efforts, the Great Lakes population in Michigan has increased in recent years, but although small numbers of birds are sporadically observed in the Duluth harbor area, the small amount of potential habitat and the intensive human use of potential nesting areas limit recovery opportunities in this area. During the 1980s, several studies funded by the DNR's Nongame Wildlife Program and the U.S. Fish and Wildlife Service monitored the Lake of the Woods piping plover population. Management techniques such as nest exclosures, brush control, predator removal, gull deterrents, and gull egg removal have been somewhat successful in reducing predation in this population. However, as a result of changing physiography, the primary Pine and Curry Island nesting site is no longer separated from the mainland; therefore, the trapping of mammalian predators was judged to be ineffective, and was discontinued. With only two or fewer nesting pairs per year in the U.S. portion of Lake of the Woods, opportunities for targeted management are limited. Whenever nests are discovered with eggs, the Minnesota DNR will continue to place nesting exclosures around them to reduce predation.

In 2001, the U.S. Fish and Wildlife Service designated approximately 325 km (201 mi) of Great Lakes shoreline in eight states, including 0.2 km (0.1 mi.) of Lake Superior shoreline in Minnesota, as critical habitat for the Great Lakes piping plover breeding population (U.S. Fish and Wildlife Service 2001). In 2002, approximately 74,228.4 ha (183,422 ac.) of habitat and 1,943.3 km (1,207.5 mi.) of river in five states, including 95.1 ha (235.2 ac.) along Lake of the Woods in Minnesota, were designated as critical habitat for the northern Great Plains piping plover breeding population (U.S. Fish and Wildlife Service 2002). Critical habitat has also been designated on piping plover wintering grounds along the Gulf and Atlantic coasts, covering birds from all breeding populations. A recovery plan for the Great Lakes piping plover population was completed by the U.S. Fish and Wildlife Service in 2003.

  References and Additional Information

Cuthbert F. J. and T. Wiens. 1982. Status and breeding biology of the Piping Plover in Lake of the Woods County, Minnesota. An unpublished progress report submitted to Nongame Wildlife Program, Minnesota Department of Natural Resources, St. Paul. 18 pp.

Ferland, C. L., and S. M. Haig. 2002. 2001 International Piping Plover Census. United States Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, Oregon. 293 pp.

Green, J. C., and R. B. Janssen. 1975. Minnesota birds: where, when, and how many. University of Minnesota Press, Minneapolis, Minnesota. 217 pp.

Haig, S. M. 1992. Piping Plover (Charadrius melodus). Number 2 in A. Poole and F. Gill, editors. The birds of North America. The Birds of North America, Inc., Philadelphia, Pennsylvania.

Maxson, S. J., and K. V. Haws. 2000. Population studies of Piping Plovers at Lake of the Woods, Minnesota: 19 year history of a declining population. Waterbirds 23(3): 475-481.

Ryan, M. J., B. G. Root, and P. M. Mayer. 1993. Status of Piping Plovers in the Great Plains of North America: a demographic simulation model. Conservation Biology 7(3):581-585.

U.S. Fish and Wildlife Service. 1988. Great Lakes and northern Great Plains Piping Plover recovery plan. United States Fish and Wildlife Service, Twin Cities, Minnesota. 160 pp.

U.S. Fish and Wildlife Service. 2001. Final determination of critical habitat for the Great Lakes breeding population of the piping plover. Federal Register 66(88):22938-22969.

U.S. Fish and Wildlife Service. 2002. Designation of critical habitat for the northern Great Plains breeding population of the piping plover. Federal Register 67(176):57638-57717.

U.S. Fish and Wildlife Service. 2003. Recovery plan for the Great Lakes Piping Plover (Charadrius melodus). United States Fish and Wildlife Service, Fort Snelling, Minnesota. 141 pp.