Natural World

Bear

One of the greatest concentrations of black bears in North America is found on Stockton Island in the Apostle Islands National Lakeshore. Bears also regularly inhabit Sand and Oak islands, and, due to their mobility, may be found on just about any of the Apostle Islands.

Stockton Island's attractiveness to local bears seems to be a recent development. Occasional sightings were reported prior to 1984. In 1984 the University of Wisconsin at Stevens Point began an ongoing study of Stockton Island's black bears by capturing a 7- year-old female and a 6-year-old male (perhaps the only bears on the island) and fitting them with radio transmitting collars. From 1984 to 1994, 133 bears were captured and marked. These bears have been monitored over the years to determine their survival rate, productivity, movements and habitat use.

The Stockton Island bear population grew steadily, reaching a peak of about 35 by 1994. The population fell to about 25 bears in 1996. The density of 2.1 bears per square mile on Stockton (in 1994) was considerably higher than the average of 1.0 bear per square mile on the Wisconsin mainland.

As the density of bears on Stockton Island increased, several changes occurred in their life pattern. Home ranges became constricted showing considerable overlap with adjacent bears. Young females began breeding at a later age than their mainland counterparts. Numerous cases of cannibalism of yearling bears by adults were documented. The weights of cubs, yearlings and adult females became significantly lower than mainland bears.

Birds

The Apostle Islands National Lakeshore, with its strategic geographic location and wide diversity of habitats, provides a refuge for birds. The Apostles were identified in the 1950s and 1960s as one of the heaviest traveled migratory flyways in the Great Lake Region. This is due to the presence of the islands reducing the distance birds have to fly over open water when migrating to areas north of Lake Superior. Outer and Long Island provide critical habitats for migratory birds: Outer for passerines, hawks and falcons, Long for waterfowl, passerines and shorebirds. In addition to these two islands, nearly all of the islands provide habitat for migrating birds. Since 1990, migratory bird surveys have been conducted on Outer and Long Islands and are part of a long-term monitoring program. There are large fluctuations in migratory volume from year to year, especially on Outer Island, most likely due to highly variable weather conditions. The islands also provide important habitats for resident breeding birds as well as neotropical migrant land birds (those, which migrate to Central and South America in winter). Over 89% of the breeding birds in the Lakeshore are migrants, 59% of which are neotropical migrants. The Lakeshore established an annual breeding bird survey in 1990 in response to the growing need to document abundance trends of neotropical migrant birds in the United Sates.

The Lakeshore provides important nesting habitat for the following colonial nesting birds: herring and ring- billed gulls, double-crested cormorants, great blue herons, and cliff swallows. Gull and Eagle Islands combined have 88% of the lakeshore's breeding herring gull populations and 80% of the herring gull breeding population on the entire Wisconsin shore of Lake Superior. Eagle Island has the only great blue heron rookery in the park.

The Lakeshore also provides nesting habitat for bald eagles (Federally threatened) and shorebirds such as the Federally and State endangered piping plover.

The Chequamegon Bay area is among the best birding locations in Wisconsin. Situated along the south shore of Lake Superior, the bay is a unique landscape feature that forms a central point for a diversity of habitats, including open water, mudflats, coastal wetlands, open fields, pine barrens, and varied forest types. As a result, the bay area hosts a wide variety of bird species that depend on these habitats during the breeding, migration, and winter seasons. Abundant public lands and extraordinary natural beauty further provide visitors with unparalleled bird watching opportunities in this exceptional area of northern Wisconsin.

This checklist includes more than 300 bird species that have been observed at least once in the Chequamegon Bay area since 1972. The list applies to areas of Ashland, Bayfield, and Iron Counties within a 40-mile radius of the city of Ashland, Wisconsin, and includes species observed by or reported to the authors.

Mammals

The lakeshore's forests have diverse disturbance histories that, through time, have strongly influenced wildlife habitat. Following logging and associated changes to habitat on the islands, there was an irruption of deer on many of the islands. Populations peaked in the 1940-1950's and were followed with major population declines in the 1960's due to excessive hunting quotas, severe winters, and habitat loss due to succession. Currently deer populations are limited to Basswood, Oak, and, most recently, Sand Islands. There may also be a low population of deer on Stockton and Long Islands and deer may occasionally swim to other islands and occur in low numbers for various lengths of time. There is a wintering deeryard on the mainland portion of the lakeshore. Hunting is allowed within the Lakeshore and a special black-powder season for deer on Oak and Basswood Islands has occurred since 1985.

Following logging and associated habitat changes, beaver became established and colonized all the available watersheds on Stockton and Outer Islands. With time, forests have matured and favorable beaver habitat has been reduced. This, in combination with flooding in the early 1990's that destroyed beaver dams and bear predation on Stockton Island, beaver populations have greatly declined. By 1994, no active beaver lodges were found on Stockton Island and recent surveys indicate that beaver numbers have declined on Outer Island. Like deer, beaver can swim between islands and are occasionally found on other islands.

Other large game species on the islands is the black bear; Stockton and Sand Islands are the only islands with a known reproducing population. Bears have overwintered and may occasionally be seen on a number of other islands. Stockton, Oak and Sand Islands are open to hunting.

Other fur-bearers include the snowshoe hare, red fox, coyote, beaver, otter, mink, fisher and muskrat. Small mammals are an important component of the lakeshore's terrestrial fauna and include: shrews, mice, voles, and red squirrels. Some wildlife species that are very common on the mainland, do not occur on the islands, including chipmunks, skunk and raccoon.

Amphibians

Amphibians have high potential as indicators of changes in the environmental quality because of their biologic sensitivity and a life cycle that involves both aquatic and terrestrial habitats for many species. Male frogs and toads advertise their presence to females by singing, each species having its own distinct call. There are 11 species of frogs and 1 toad, collectively called "anurans", in Wisconsin.

The Wisconsin Department of Natural Resources (DNR) has been coordinating statewide frog and toad surveys since 1984. In cooperation with the DNR's monitoring program, the Lakeshore audio frog and toad surveys were begun in 1990 to determine long-term statewide population trends. As a protected area, Apostle Islands may also serve as a control against which population trends could be compared with intensely managed areas. Apostle Islands provide prime habitat for amphibians that includes mixed hardwood and boreal forests, bog, lagoons and streams of the. Typical species of the mixed hardwood forest found in the park include the Spotted Salamander, Gray Treefrog, Northern Reed-bellied Snake and Northern Ring-necked snake. In the moister forest Wood Frogs, Blue-spotted salamanders, Red-backed salamanders are found, while Mink Frogs and Northern Leopard Frogs inhabit pond and lake edges. Some of the hardy amphibian and reptile species that survive in a variety of habitat types within National Lakeshore are Northern Spring Peeper, American Toad, Painted Turtle, and Common Garter Snake.

Fish

Fish

Early explorers were amazed by the rich fish population of the world's greatest lake. Years of heavy fishing pressure took a toll on fish populations, but the most severe blow came with the arrival of the sea lamprey. By the 1950's this parasitic species had devastated much of the native fish population.

Intense efforts by both U.S. and Canadian governments have succeeded in minimizing the havoc currently wrought by the sea lamprey, and some fish populations have rebounded. The restoration of the lake trout population is perhaps the biggest success story: this species, once on the verge of disappearance, once again maintains a viable population in the cold, clear waters of Gitche Gummee.

Animals

Animals

Island environments, naturally isolated, provide important habitat for numerous bird species, mammals, plants, amphibians and aquatic species. Wildlife species are characteristic of the southern limits of the boreal and northern limits of the hardwood/hemlock forests. Game species include whitetail deer, black bear, snowshoe hare, waterfowl, woodcock, and ruffed grouse. Other fur-bearers include the red fox, coyote, beaver and otter. Small mammals are an important component of the lakeshore's terrestrial fauna and include: shrews, mice, voles, red squirrels and chipmunks. Some common mainland species do not occur on the islands, including raccoon, skunk, porcupine, gray squirrel, chipmunk and woodchucks.

The Apostle Islands area is important for commercial and recreational fishing. Shoals near the lakeshore's ¼ mile lakeward boundary provided critical spawning areas for the commercially important lake trout and whitefish. The fish community presently found within the relatively shallow Apostle Islands waters is diverse and complex for waters such as Lake Superior.

The islands within the park provide important habitat for resident breeding birds as well as neotropical migrants. The great majority of nesting forest bird species in the Apostle Islands are migratory. The lakeshore includes important migratory bird concentration points during spring and fall migration.

Nature & Science

"Nature, even when she is scant and thin outwardly, satisfies us still by the assurance of a certain generosity at the roots."
 

- Henry David Thoreau (1817-1862)
A Week on the Concord and Merrimack Rivers, 1849

Set in a matrix of Lake Superior, the largest and most pristine of the Great Lakes, the Apostle Islands archipelago includes 22 islands and is located in far northwestern Wisconsin, off the Bayfield Peninsula. Twenty-one of these islands, and a 12-mile segment along the shore of Wisconsin's north coast, comprise the Apostle Islands National Lakeshore.

The beauty of the islands are enhanced by the area's geology. Colorful precambrian sandstone have eroded into interesting cliff formations, including sea caves, and there is a highly diverse collection of sandscapes, including sandspits, cuspate forelands, tombolos, a barrier spit, and numerous beaches. These sandscapes are among the most pristine left in the Great Lakes region.

The lakeshore is at the continental northwestern limits of the hemlock-white-pine-northern hardwood forest and also contains elements of the boreal forest. The lakeshore's forests have a wide variety of disturbance histories, ranging from pristine old-growth forest without a history of deer browsing, to forests that have been subjected to logging, fires and extensive deer browsing. At present, most of the Lakeshore is covered with unbroken mature second growth forest. There is an interesting interplay of cultural and natural resources that occurs in the Lakeshore. The old-growth forests that remain on Devils, Raspberry, Outer, Sand Islands due so because they were part of lighthouse reservations set aside by the U.S. Lighthouse Service.

The island's wildlife includes a diverse population of nesting and migratory birds and a variety of mammals, amphibians, and fish. Following logging and associated fires, favorable habitat for deer and beaver was created on many of the islands. Pre-disturbance forest had a fairly dense ground cover of Canada yew, which is still present on islands without a history of deer. On Islands with deer, however the yew was rapidly browsed to near extinction, and some areas remain at that level today. Deer numbers peaked in the early 1940-50's but by the early 1960's, deer were driven to very low numbers through liberal hunting quotas. Today the deer population is relatively low but appears to be increasing on Oak and Sand Island.

This fascinating unit of the National Park System features a combination of spectacular natural beauty and rich cultural history. The rich history of the islands includes Native Americans, voyageurs, loggers, quarrying, farmers and commercial fisherman. The six historic light stations in the park, built here to aid Great Lakes navigation, are the largest such group found in any unit of the National Park System.

The islands offer various water- based recreational opportunities such as sailing, power boating, sea kayaking, fishing and scuba diving.

Plants

Plants

The Apostle Islands National Lakeshore provides regionally diverse and unique plant communities. This is due primarily because it lies in the tension zone between the boreal and temperate forests. Thus, the islands and their forests comprise an ecosystem that is unique in North America.

In pre-settlement times about 90% of the islands were covered by an upland mixed coniferous/hardwood forest dominated by hemlock, white pine, sugar maple, yellow and white birch. The boreal forest community is dominated by white spruce, balsam fir, tamarack, white cedar, birch, and aspen.

Most of the islands have a history of logging however; a few of the islands (North Twin, Devils, Raspberry, Long, Eagle, Gull) have never been commercially logged and have old growth remnant forests. Today, maturing second growth forest exist throughout the islands.

Over 800 plant species occur within the lakeshore, including Wisconsin State listed endangered and threatened species. Following logging, deer populations irrupted on many of the islands, severely impacting species favored by deer, such as Canada yew. Several of the islands, however, that did not have a history of deer populations and others that had moderate deer populations have lush stands of Canada yew, a very rare species on the mainland due to deer browse. Currently, deer populations occur on only a few islands.

Wetlands within the lakeshore include bogs associated with sandscapes, perched bogs, lagoons, alder thickets and beaver flowages. These wetlands contain unique flora and fauna and add a considerable amount of ecological diversity to the lakeshore. Bogs dominated by sedges, ericads and Sphagnum mosses often occur in the filled-in lake basins that occur just inland from sandscape dune ridges. The larger bogs on Michigan, Outer, and Stockton Islands have lagoons with floating and submersed aquatic species. Bogs found on poorly-drained summit plateaus are often smaller and have poorer bog floras than their coastal, sandscape counterparts.

About one-third of the Islands coasts consists of precambian sandstone ledges and bluffs. Local vegetation on these rock faces depends on the microhabitat and can vary from common willows and weed species, to subartic rarities and species with calcareous tendencies. Steep reddish clay bluffs are vegetated with small trees of balsam poplar, white birch, red maple and showy mountain ash.

The lakeshore has a rich assemblage of dunal features. Dunal vegetation, beach grass and beach pea, as well as a shrub and forest component of speckled alder, quaking aspen and white birch dominate these sandscapes.

Natural Features & Ecosystems

The Apostle Island archipelago's sandstones were deposited during the late Precambrian era, about 600 million years ago, and form the basement rock for all the islands. The upper and lower most layers (Chequamegon and Orienta formations) are in the Precambrian Bayfield Group and were deposited by northeastward-flowing braided streams. The Devils Island Formation, between the sandstones, represents deposition across sand-flats that were intermittently covered by shallow ponded water. The Pleistocene ice advances provided an abundance of till, with lesser amounts of glacial outwash, which covers most of the island. Some glacial drift was streamlined by overriding ice. Terraces, wave-cut benches, and elevated beaches show evidence of higher levels of Lake Superior. High bluffs and glacial drift erode to provide sand for today's sandspits and cuspate forelands. The Apostles were glaciated repeatedly, with the most recent glaciation was by the Vanders Ice Lobe approximately 12,000 years ago. In the wake of this ice lobe melt waters varied drastically in elevation and longevity. Glacial Lake Duluth submerged most of the Bayfield Peninsula and the islands. Continued and rapid deglaciation opened up new drainages and with land rebound, it lowered the lake level making the Apostles part of the Bayfield Peninsula. Following these extreme periods of rising lake levels controlled by land rebound, the Apostles were separated from the peninsula to form the archipelago. Above the bedrock there are regionally rare habitats that exist in the lakeshore. These habitats include old growth forests, clay bluff communities, sandstone communities, lagoonal and bog communities, and dunal communities. The Wisconsin Department of Natural Resources Natural Heritage Inventory Program has designated Maritime Forest, Sandscape (includes beaches, sandspits, cuspate forelands, and tombolos), and Maritime Cliff State Natural Areas within the Lakeshore.