DEEP: Conservation


Many of Connecticut's uncommon and rare species are near the northeastern limit of their continuous range. They inhabit small areas of specialized habitat in western Connecticut, or low-lying river valleys, and may never have been widespread within the state. Examples of these include the bog turtle, five-lined skink, and spadefoot toad. Several species, including the spring salamander and northern redbelly snake, are primarily restricted to the hills of northern Connecticut and are much more widely distributed in the upland regions of central and northern New England. Although all species have been subject to collecting pressure, several species are directly threatened by collection, including the bog, wood, spotted, and box turtles, as well as the timber rattlesnake.

Road mortality seriously affects populations of amphibians and reptiles. Although all species are vulnerable to this factor, long-lived, slow-maturing species with low reproductive outputs, including certain snakes and the majority of turtles, are most seriously affected by the steady attrition of reproductively active adults. The loss of even a few box turtles per decade from a population is not sustainable over the long term (Doroff and Keith, 1990). Many of Connecticut's highways have developed "kill zones" parallel to, and extending hundreds of feet from, the edge of the road. Kill zones are characterized by greatly reduced numbers of reptiles, a direct effect of road mortality exceeding the capacity of populations of long-lived, slow-maturing reptiles to replenish their numbers over time. Amphibians that migrate en masse to breeding sites, including wood frogs and mole salamanders, are vulnerable to large scale mortality if the migration occurs at a time of night when road traffic is high. Development and changing land use patterns often affect specialized, ecologically vulnerable habitats that contain a high proportion of uncommon species. For example, vernal pool breeding species, including the wood frog, Jefferson, marbled and spotted salamanders, are especially vulnerable (Klemens, 1998a). These species are declining statewide because of the loss of large tracts of forested habitat that surround these small wetlands. Although many towns protect the vernal pool wetland breeding habitat, there is minimal protection of the upland habitats that surround these pools. These forested uplands that extend 500 feet or more from the edge of the vernal pool are critical habitat that these animals depend upon most of the year for foraging and hibernation.

An additional challenge to conserving vernal-pool breeding amphibians, as well as many other amphibians and reptiles, is that populations of species rarely occur in isolation from one another. What the casual observer may perceive as series of breeding pools, each with its own resident population of amphibians, actually function as a metapopulation. There is gene flow between these pools, and, in times of ecological catastrophe at one site, such as the loss of a large portion of the breeding population, dispersal from other nearby sites can help replenish the population. I observed one such instance in the spring of 1999 in the Appalachian Mountains of southern Pennsylvania. Here, an early warm spring rain had triggered a mass migration of Jefferson salamanders to their breeding pools. These pools were scattered for about a kilometer along a ridgeline. This warm, rainy night was followed by an extended period of very cold weather. The open pools completely refroze, and several storms then covered the iced over pools with a heavy snow layer. Although Jefferson salamanders can sustain extended periods submerged in cold water, they cannot survive being entombed and subsequently suffocated, unable to obtain oxygen at the surface of the pools. Although every pool examined held dead salamanders, a single spring-fed pool had no mortality. This illustrates how important this single pool was in this particular year, and probably will be for several years afterward, as such a large percentage of breeding adults was lost in the other pools.

Maintaining these landscape-scale ecological connections is one of the biggest challenges that we face in conserving amphibians and reptiles. Spotted turtles use a variety of different wetlands and upland habitats within a landscape mosaic of habitat. Again, in order for this species to sustain itself over the long term, it is insufficient to simply protect the various wetlands that it uses as single entities without recognizing and then protecting the connectivity between these wetlands through the intervening upland habitat. It is also important to understand the impediments that different types of human uses on a landscape can pose to amphibian and reptile movements. For example, many species of amphibians are able to disperse across agricultural fields at night in cool wet weather. If these fields were replaced with a housing subdivision, a common occurrence, and even if some portions of the habitat were reforested, the system of roads, curbs, catch basins, and the activities of the human inhabitants pose a far greater obstacle to the dispersal of amphibians than did the former agricultural landscape. These ecosystem-scale landscape requirements of amphibians and reptiles pose a tremendous challenge to local land-use decision-makers. It requires a much broader look at the overall ecosystem, rather than the site-specific project reviews that are the current norm.

While many of Connecticut's amphibians and reptiles that have complex habitat requirements and life history strategies encompassing multiple habitat types are in decline, a small group of species are on the increase. Species including the bullfrog, snapping turtle, and brown snake are able to survive in human-altered landscapes that are increasing within the state. As wooded swamps and other diverse shallow wetlands are converted into ponds, bullfrogs, snapping turtles, and painted turtles increase, exploiting habitats that once supported wood frogs, spotted turtles, and ribbon snakes. Although many towns stringently protect their wetlands, they often fail to adequately protect the complexity and structure of these wetlands. Wetlands that are structurally complex, with many layers of shrubs and vegetation, support a rich diversity of amphibians and reptiles. When these wetlands are replaced by ponds, which often occurs when land is developed, the complexity of the wetland and its rich biodiversity are lost. A major challenge that land-use decision-makers and conservationists will face in the twenty-first century is to sustain the biodiversity (species richness) of Connecticut's amphibians and reptiles. This will require maintaining habitat complexity and connectivity by examining a much larger landscape scale, often more than 1,000 acres, when evaluating the environmental impacts of a development proposal.

One of the fundamental dilemmas that town planning boards and wetland commissions face is that the majority of projects that they review fall well below 100 acres in size, whereas many wetland-dependent amphibians and reptiles require a minimum of 1,000 acres that is a mosaic of upland and wetland habitats (Klemens, 1998a; Lassila, 1999). The land-use review mechanisms designed to protect the environment often fall short of that goal by failing to consider impacts at an ecosystem scale. Ironically, because the current environmental and land-use review processes are often conducted at too small a scale, they actually encourage habitat fragmentation (and destruction) of Connecticut's wetland and terrestrial ecosystems. However, this does not have to be the case. A growing number of Connecticut towns have already begun to consider ecosystem-scale in their land-use planning and decision, adding both value and effectiveness to the environmental review process. Such efforts logically lead to focusing more intense development in certain areas, while leaving larger tracts of open space between developed areas. This ecosystem stewardship approach results in a very different pattern of suburban development than has occurred over much of the state. Fragmentation of large tracts of second growth forest into ever smaller, ecologically dysfunctional patches is replaced with more tightly clustered development around existing hamlets and urban centers, with large blocks of open space and lower density development zones retaining ecological connectivity and rural character.

Amphibians and Reptiles in Connecticut