UNIQUE HABITAT OVERVIEW
Introduction
Lake Erie Islands
Oak Savannas
Boreal Communities
Ohio's Caves
Lake Erie Watersnake
Karner Blue Butterfly
Introduction
A group of unique habitats bolster Ohio’s diversified wildlife resource. What makes these habitats unique is that they are capable of supporting types of wildlife with highly specialized habitat requirements or species at the fringe of their wider U.S. range; these habitats themselves may also be confined to relatively small areas within the state. Ohio's primary examples of unique habitats include Lake Erie islands, oak savannas, the boreal (snowbelt) community, and both natural and man-made caves. Rich and diverse assemblages of flora and fauna are associated with each habitat. In addition to conserving these remnant habitats, opportunities also exist to enhance man-made structures which simulate natural habitats for some wildlife, such as utilizing mines as hibernacula (winter roosts) for the Indiana bat and skyscrapers as nesting sites for peregrine falcons.
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Lake Erie Islands
Twenty-two Lake Erie islands lie between the Canadian and American shores of the Western Basin of Lake Erie. Ohio has jurisdiction over 13 of the islands which range in size from the 1.2-acre Starve Island with 0.2 mile of shoreline to the 2,824-acre Kelleys Island with 11.6 miles of shoreline. Although the Lake Erie islands are distinct from the neighboring mainland in climate, topography, surface geology and soils, they are vegetatively similar to the surrounding mainland. Shoreline characteristics vary from island to island but consist of beaches of sand, gravel or small stones, loose rocks, limestone shelves, and shear cliffs—all with varying amounts of vegetative cover. Human disturbance, habitat degradation and destruction, coupled with shoreline alteration and development, are the most serious threats to island-dependent wildlife.
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Oak Savannas
Oak savannas are limited to the northwestern portion of the state along a sandy, 6 x 22 miles long belt of soil known as the Oak Openings in parts of Henry, Fulton, and Lucas counties. This area encompasses 130 to 140 square miles. Oak savannas are dry areas dominated by drought-resistant prairie plants such as little bluestem grass, lupine, and widely-spaced oak trees that are often surrounded by areas of poor drainage which support wetlands. Residential and commercial development in the region has fragmented the remaining oak savanna habitat into isolated patches.
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Boreal Communities
Boreal communities are generally thought of as areas which occur in more northern regions of the continental U.S. and Canada. However, both boreal flora and fauna occur in extreme Northeastern Ohio. The Boreal Community today is limited to the eastern 1/3 of Geauga County, the northern 1/3 of Trumbull County, and those portions of Ashtabula County where the average annual snowfall exceeds 60 inches. Losses of boreal habitat can be attributed primarily to agriculture, and to a lesser degree to recreation, water level changes, mining, and development. Many boreal areas have been destroyed, fragmented, and isolated as a result of commercial, industrial, and residential development.
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Ohio's Caves
Most of Ohio's caves occur in a 40-mile-wide tract of land aligned north-south through the middle of the state. Approximately 300 known caves span the state from Adams County to the Lake Erie Islands. In addition to naturally formed caves, there are more than 4,000 recorded inactive underground mines resulting from mineral extraction. Most of these mines were the product of coal extraction and lie in the unglaciated region of the state. Human disturbances (resulting from recreational caving, commercialization, and vandalism) are the most serious threats to cave-dependent wildlife.
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Lake Erie Watersnake
The Lake Erie watersnake (Nerodia sipedon insularum), a subspecies of the Northern watersnake, comes in a variety of colors, ranging from banded gray and brown blotches to solid gray. The Lake Erie watersnake is a federally threatened and state endangered species. This snake has 1 of the smallest geographic ranges of any vertebrate in the world and is only found on the islands of Lake Erie. Lake Erie watersnakes are active primarily between early May and October,depending on seasonal temperatures and weather. Snakes typically enter hibernation betweenmid-September and mid-October. When not hibernating, the snakes spend most of their time near the lake’s edge basking on the rocky shoreline or foraging just offshore. The snake’s diet is composed mainly of non-game fish & amphibians found in and around rocks and vegetation near the shore and in the lake’s near-shore waters. Recent studies have shown that the snakes eat mostly the round goby, an aquatic nuisance species. They mate from late May to early June by forming “mating balls” consisting of 1 female and several males. Live birth of 30 or so pencil-sized young occurs in early September. Only about 15% of the young survive their first year. The snake has benefited from the construction of docks and shoreline protection done in a snake-friendly manner demonstrating its ability to coexist with humans, a condition necessary for the snake to persist on the islands.
The current distribution of Lake Erie watersnakes is reduced compared to their historic distribution. The historic range of the Lake Erie watersnake included 22 or more offshore islands and rock outcrops (12 U.S. offshore islands, 9 Canadian islands, and various rock outcrops) of western Lake Erie, shorelines of the Catawba/Marblehead Peninsula, and nearshore islands (Mouse and Johnson) in Ohio. Today, Lake Erie watersnakes no longer occur on 3 islands: Middle Sister Island (Ontario), North Harbour Island (Ontario), and West Sister Island (U.S.).
Recent data show fluctuations in population density (i.e., number of LakeErie watersnakes per km of shoreline). Comparisons of population density estimates over time suggest that population sizes generally decreased from 1980-85 to 1988-92 (by 33 adults/km at 3 sites), and from 1988-92 to 1996 (by 13 adults/km at 4 sites). Comparisons of population density estimates also suggest that population sizes generally increasedfrom 1988-92 to 2000-02 (by 23 adults/km at 3 sites), and from 1996-98 to 2000-02 (by 88 adults/km at 10 sites).
Population Surveys
The Lake Erie watersnake has declined in population abundance and distribution from historic levels. At the time of listing (1999), the estimate for the U.S. population ranged from 1,530 to 2,030 adults, and U.S. populations of the Lake Erie watersnake were restricted to only 8 islands. Population fluctuations during the late 1990s and early 2000s, which coincide with intensive public outreach efforts and Federal listing of the snake, have resulted in increases and decreases in local populations, but in general, populations appear to be increasing. Results of surveys on Kelleys, South Bass, Middle Bass, North Bass, Green, and Sugar Islands conducted from 2000-2002 suggest that the U.S. population of Lake Erie watersnakes on these islands was nearly 5,500 adults. In the 7 years since listing, the adult population estimate has more than doubled, likely due to increases in the actual snake population as well as improved survey data. Also since the time of listing, Lake Erie watersnakes have recolonized GreenIsland, from which the snakes had previously been extirpated. These 2 events demonstrate that recovery of the snake population is already well underway.
The 2008 capture-mark-recapture estimate is 9,336 adult snakes. The total population estimate, which includes shoreline habitats outside the surveyed area, is more than 12,000 adult watersnakes. This exceeds the 5,555 adult snakes needed for the species to be deemed recovered as specified in the Population Persistence criterion of the Lake Erie Watersnake Recovery Plan.
Population surveys were first extensively conducted by Dr. Richard King, Northern Illinois University, in the mid-1980s. Expanded surveys by King were funded by the Division of Wildlife throughout the 1990s. In 1999, the Division and the U.S. Fish and Wildlife Service jointly funded a 3-year study to research the population size, movement patterns, foraging behavior, and hibernation sites of the Lake Erie watersnake on the U.S. islands. Much of the data gathered from this study and past work by King and Research Associate Kristin Stanford were utilized in developing the U.S. Fish and Wildlife Service’s Lake Erie Watersnake Recovery Plan. Mark-recapture and telemetry work are ongoing with neonates being marked for a survivorship study. Stanford resides year-round along the Lake Erie shoreline continuing research and promoting Lake Erie watersnake conservation through a variety of public programming and outreach activities.
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Karner Blue Butterfly
The Karner blue butterfly has a wingspan of about 1 inch, roughly the size of a postage stamp. The upper surface of the male is blue with a black edge and white outer margin, and the female is similar but more brown or grayish in color, with a row of dark spots with orange crescents along the wing margins. The underside of both sexes is similar, being slate gray with several marginal rows of orange and black spots. In Ohio, there are several commonly occurring blue butterflies, including the spring azure and the Eastern tailed blue, that are frequently confused with the Karner blue.
The Karner blue butterfly historically occurred along a narrow geographic region from eastern Minnesota, across portions of Wisconsin, Illinois, Indiana, Ohio, Pennsylvania, Massachusetts, New York, and New Hampshire, as well as the Province of Ontario. Karner blues are generally associated with oak savannas. In Ohio, oak savannas are primarily limited to a small region known as the "Oak Openings," which extends through LucasCounty into a portion of Fulton and Henry counties. Last seen in Ohio in 1988, the butterfly has declined substantially throughout its range and is thought to be extirpated from Ontario, Massachusetts, Pennsylvania and Illinois. The Karner blue is a federally and state endangered Lepidoptera found in oak savanna habitat and is closely associated with wild lupines, prairie grasses, and nectar plants such as butterflyweed. The Karner blue's habitat has been dwindling as a result of residential and commercial land development and the lack of natural disturbance, such as wildfires. Such disturbance helps to maintain the butterfly's habitat by controlling forest succession and encouraging lupine and other prairie species growth.
Population Surveys
In 1998, the first reintroduction of the Karner blue butterfly to its native habitat in the United States occurred in Ohio. Annually, 40 female Karner blue butterflies have been collected from the wild, in cooperation with the Michigan Department of Natural Resources, and taken to the Toledo Zoological Gardens to raise larvae for reintroduction in Ohio. Captive-reared butterflies are then released on restored habitat at The Nature Conservancy's Kitty Todd Preserve in LucasCounty.
Captive breeding protocol developed by the Toledo Zoological Gardens has been instrumental in establishing fundamental principles necessary to successfully establish other Karner blue captive breeding programs in the United States. These methods have also been successfully applied for other Lepidopteron species conservation in Ohio.
2009 was the fifth year for Karner blues to be released at a second site within the Kitty Todd Preserve. 1,039 adult butterflies were released at the Moseley Barrens, which is approximately 14 acres on a parcel of land approximately 300 acres in size one-half mile from the original Kitty Todd Preserve release site. A third release site was established at the Oak Openings Preserve in the Toledo Metroparks with 313 captive-reared adult butterflies released.
In partnership with the Division of Wildlife, Cleveland Museum of Natural History, and the Ohio Biological Survey, Inc., the Ohio Lepidopterists established a statewide butterfly monitoring program in 1998. Currently there are 65 active transects located in 29 counties. Long-term data can provide a wealth of information including fluctuations in numbers due to short-term and long-term effects, colonization and extinction as habitats undergo succession, expansion and contractions of range, migrations, immigrations of non-native species, flight periods of butterflies, seasonal variations in abundance, and overall health of the butterflies of Ohio.
Visit www.ohiolepidopterists.org/bflymonitoring/ to learn more about Ohio’s butterflies and how they are monitored.
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