Conserving Borderline Species: A Partnership between the United States and Canada
Reptile
Lake Erie Water Snake (Nerodia sipedon insularum)
Status
Canada (COSEWIC): Endangered
U.S. (USFWS): Threatened
Photo Robert J. Willson
Description
The Lake Erie water snake is a nonvenomous reptile that grows to almost 1 meter (3 feet) in length. The snake does not have fangs, but rather tiny teeth or ridges similar to those of some large trout. It usually retreats when approached by people. If threatened, however, the snake tends to flatten its head and body, and may strike out to give a pinching bite. In an effort to escape when captured, it might release a foul smell. The adult Lake Erie water snake is uniformly gray or has incomplete band patterns, plus dull body and shiny head scales. The Lake Erie water snake resembles the closely related northern water snake, but often lacks the body markings, or has only a pale version of those patterns.
Ecology
During warm months, Lake Erie water snakes usually stay close to the shoreline, seeking the shelter of shrubs lining beaches or the trees along rocky shores. They feed on fish and amphibians in nearby waters up to 9 meters (30 feet) deep. The snakes congregate to breed. The offspring hatch from mid-August through September. The average clutch size is 23 young. During winter months, they move farther inland above the water and ice line. They hibernate in crevices of cliffs, rocky areas, tree root clusters, animal burrows, quarries, deserted cisterns and drainage tiles, old rock walls, or foundations.
Causes of Decline
The Lake Erie water snake once inhabited 22 offshore islands and rock outcrops of western Lake Erie between the Ohio and Ontario mainland, and a portion of the Ontario mainland. It has disappeared from the Ontario mainland and several islands in both countries. It is now known primarily from only eight U.S. islands (Ballast, Gibraltar, Kelleys, Middle Bass, North Bass, Rattlesnake, South Bass, and Sugar) and four Canadian islands (East Sister, Hen, Middle, and Pelee). The snake inhabits the shoreline areas, nearshore waters, and nearby rock outcrops of these 12 islands.
The current estimate for the U.S. portion of the population ranges from 1,500 to 2,000 adults. The Canadian population is unknown. Persecution by humans is a major cause of the snake's decline and continues to be a chief threat. Loss of habitat from shoreline alteration and development over the past 60 years has also been a major cause of its decline. Other current threats include pesticides and oil spills.
Research and Recovery
Cross-border cooperation in the recovery of the Lake Erie water snake is a key objective for both Canada and the United States. In 1984, researchers assessed the population status, distribution, and habitat needs of the Lake Erie water snake in Ohio and Ontario waters. Since 1992, Canadian scientists have been working on a recovery plan with several long-term objectives, including developing liaisons with U.S. Federal agencies and the State of Ohio. In the United States, the U.S. Fish and Wildlife Service and Ohio Division of Wildlife are developing a Federal recovery plan and pursuing conservation plans on certain islands. Other key objectives under both plans will be to identify all suitable habitat types, and protect, enhance, monitor, and increase the population.
The U.S. portion of the population was reassessed in 1997 and 1998. Of five core islands most important to the snake, one is in Canada and four occur in the United States. On Pelee Island, Ontario, Provincial preserves at Fish Point and Lighthouse Point protect Lake Erie water snake habitat. In the United States, the U.S. Fish and Wildlife Service and the Ohio Division of Wildlife have conducted a public outreach program on the Lake Erie islands since 1994. The program encourages island residents and visitors to adopt a "live and let live" attitude toward snakes living among them. It includes a poster contest, an outdoor sign campaign, and personal contacts to inform island residents and visitors that Lake Erie water snakes are nonvenomous and pose little threat.
In the future, cooperating wildlife agencies expect public participation (for example, education, planning, project consultation) to play an important role in the Lake Erie water snake's recovery. Consultations might bring about additional habitat protection, habitat restoration, and modification of construction activity. Some day, beneficial shoreline projects could contain designs that utilize rock and vegetation to provide cover and forage areas for Lake Erie water snakes.
