Caring for the habitats of our rarest species

Our region has a number of unusual wildlife habitats, some of which are considered quite rare. We have just three federally listed rare species, however, recognized as endangered or threatened under the federal Endangered Species Act. These are the Indiana bat (Myotis sodalis); the small whorled Pogonia (Isotria medeoloides); and the bog turtle (Clemmys muhlenbergii). True, we also have a globally rare pond weed, Potamogenton Ogdenii, but because it is a fertile hybrid of two other aquatic plants it is not eligible for federal recognition as a rare species. Other species that were found here historically but officially considered extirpated include the gray wolf and the eastern cougar. The latter animal (except for the Florida panther population), has been declared extinct by the United States Fish and Wildlife Service (USFWS), while the American bald eagle is no longer federally listed as a rare species.There has been only one recent record for Indiana bat in all of Connecticut (1997), and it has declined in overall numbers by more than 56 percent since it was federally listed as endangered in 1967. For a species that was at one time considered abundant throughout its range, the destruction of forests and disturbance of the small number of caves that provide its winter habitat are considered likely causes of its increasing rarity. It is also vulnerable to the killer fungus commonly known as white nose syndrome, which in recent years has caused high mortality for many overwintering bat species. One of the rarest orchids in eastern North America, the small whorled pogonia, is federally listed with as a rare species with threatened status. It is now the subject of a 5-year review by the USFWS to determine whether its conservation status has changed. This woodland plant is recorded in Connecticut at just one site, a location in a state forest in Litchfield County that is unfortunately considered nonviable. Habitat destruction, excessive deer browse and illegal collection are all factors that affect the survival of this species. Saving turtle habitats And then there is the bog turtle, a species much in the news of late in our area in association with a proposed development project in the New York state town of Northeast (Northeast includes the village of Millerton). Of our three federally listed rare species, this is the only one that I have personally observed in our region, and only because my past work with the Nature Conservancy had me directly involved with bog turtle conservation. Nonetheless, I did once come across a bog turtle crossing one of our rural roads. I thought at first it might be a spotted turtle, also considered rare in our area although not a federally listed species, but it proved to be an old female bog turtle, the bottom of her carapace nearly worn smooth from decades of slow travel. There was a tiny notch to the left of her head on one of the scutes of her shell, which I recognized as part of the identification system used by researchers to identify individual turtles at sites where they have been studies. This allowed me to determine that the animal had been first observed more than 20 years before by Dr. Michael Klemens. Bog turtles are very small, barely 4 inches long. They are not at all easy to find, even in places where they are known to occur. They prefer wading to swimming and their preferred seepage wetland habitats tend to become less hospitable to them as shrubs replace sedges and shade covers their basking areas. Bog turtle habitats tend to occur in a patchy mosaic with some distance between them. Perhaps this old turtle, more than half a mile from the site where she was first observed, was dispersing in search of a site more to her liking. This is why it is important to protect suitable bog turtle habitat even if it is not currently shown to be occupied.A combination of natural disturbance, soil saturation, beaver pond abandonment, fires set by native Americans and even browsing of woody vegetation by long-extinct mastodonts would have once maintained and created new bog turtle habitat. Later management as wet pasture may have have kept some bog turtle habitats from succeeding to shrubby vegetation. A number of other factors affect the viability of bog turtle sites, including alteration to ground- and surface-water hydrology, excessive nutrient inputs, barriers to dispersal between suitable habitats, changes in vegetation composition and structure due to invasive species, introduced diseases and illegal collection of individuals. A turtle network Researchers with the USFWS estimate that even our best remaining bog turtle sites will lose viability if adult mortality occurs at the rate of a single individual every year. We are already at that number in the Tri-corner area.The bog turtle is near the extreme limit of its contiguous range in our area. The only one place where bog turtle populations in New York have the opportunity to connect with those that remain in Connecticut, and through them perhaps form a metapopulation with the few remaining sites in the Southern Berkshires, occurs right here in Northeast and Salisbury. Sites that become isolated from each other lose genetic diversity and are highly vulnerable to being lost altogether. When the break happens in a chain of otherwise connected sites, there can be dire consequences for populations up and down the line.At the end of the day, what does it matter if the rarest of the rare species disappear from our region? We do not truly know the impact on our forests of the loss of the American chestnut as a canopy species in the early 20th century, or of the extinction of passenger pigeons that once feasted on our nut trees in such great numbers that the birds seemed to block the sun. One could argue that there may well be a connection between between the survival of the white footed mouse, larval host to Lyme-disease infected ticks, and the availability of acorns that would otherwise have been eaten by passenger pigeons. It may well be a question of better safe than sorry. Tim Abbott is program director of Housatonic Valley Association’s Litchfield Hills Greenprint. His blog is at greensleeves.typepad.com.