Gravel Island National Wildlife Refuge

Gravel Island National Wildlife Refuge
IUCN category IV (habitat/species management area)
Location	Liberty Grove, Door County, Wisconsin, United States
Nearest city	Rowleys Bay
Coordinates
Area	28 acres (11 ha)
Established	1913
Governing body	U.S. Fish and Wildlife Service

Gravel Island National Wildlife Refuge is a National Wildlife Refuge located off the Door Peninsula in Wisconsin. Founded in 1913 the refuge consists of two Lake Michigan islands, that act as nesting grounds for native bird species. The refuge is part of the Wisconsin Islands Wilderness Area, and as such it is off-limits to the public to preserve the habitat of the islands. It is inhabited by large colonies of shore birds, waterfowl and also home to a pair of great black-backed gulls, one of farthest westward breeding sites of the species.

History

File:Spider Island Tagging.JPG

FWS staff banding cormorants as part of tagging operations at the refuge.

In the years before the refuge's founding, multiple expeditions were made to the Islands. One Ornithologist named Henry L. Ward, then-curator of the Milwaukee Public Museum visited the area numerous times to study the herring gull populations. In 1906 and 1907 while visiting Gravel Island, he noted very large colonies of herring gulls as well as Caspian terns, observed their behavior and collected specimens from the island. In 1913, under executive order the refuge was formed from Gravel Island and Spider Island to protect the breeding grounds of birds living there. Upon its formation it became the 29th refuge in the U.S and third in the great lakes region. In 1970 the refuge became part of the Wisconsin Islands Wilderness Area, one of the smallest in the country. Many studies have been performed at the refuge since the 1970s, and in recent times efforts have focused on migrating habits, breeding and tagging of the birds.

In 2009 the refuge became part of a Comprehensive Conservation Planning (CCP) program which will help manage the refuge more efficiently. The plan will allow for long-term continuity in refuge management, make sure that the refuge is consistent with the policies of the National Wildlife Refuge System and improve budgets for the refuge.

Geography and geology

The refuge covers 28 acres (11 ha) which comes from two islands, Spider Island spanning 23 acres (9.3 ha) and Gravel Island at a size of 4 acres (1.6 ha). The refuge is located off the east side of the Door Peninsula in Lake Michigan near Porte des Morts or "Death's Door", and is in a geographically rugged part of the Niagara Escarpment. The islands are made of mainly limestone, with little to no vegetation growing on them. They were shaped by years of receding water, powerful pre-glacial rivers, and advancing glaciers. As a result, the islands are mainly flat and stick up only a few meters above the lake.

Wildlife and ecology

Flora

Spider island had a birch-cedar-tamarack forest until the late 1970s, but succumbed to the thousands of birds living on the island. The trees of Spider island have now fallen over or been washed away and no permanent vegetation is known on Gravel island.

Fauna

The refuge is home for to a wide array of bird species that either use the islands as nesting grounds or a place of shelter. The great black-backed gull (Larus marinus) is known to have a small breeding colony on Gravel Island, and historically on Spider Island. In 1994 the species was discovered on Spider Island, making it the westernmost breeding on record at the time. Large colonies of herring gulls (Larus smithsonianus) and double-crested cormorants (Phalacrocorax auritus) are found on both islands, while a colony of Caspian terns (Sterna caspia) can be found on Gravel Island. Scattered populations of waterfowl nest on Spider Island; these include the Canada goose (Branta canadensis), American black duck (Anas rubripes) and mallard (Anas platyrhynchos).

External links

• Park Main Page