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Recovery strategy for the Eastern ribbonsnake (Thamnophis sauritus), Atlantic population in Canada

4. Knowledge gaps

Currently, there are knowledge gaps on all aspects of the life history of eastern ribbonsnakes, including demography and current population trends, historical status, habitat requirements at specific life stages, and severity of threats. At the present time, the three most important questions are as follows:

  1. What is the current status of the Nova Scotia population of eastern ribbonsnakes?

    It is important to identify the current range of the population and the spatial distribution within that range. It is not known at what spatial scale genetic structure is evident, if ribbonsnakes from neighbouring sites interact with one another, and what factors constrain movements, if any, between concentrations of ribbonsnakes. If individual concentrations are isolated, it will be important to determine if it is historical or the result of recent anthropogenic events. Crucial information on basic life history traits such as abundance, survivorship and longevity is also lacking; all required to determine if populations are increasing, decreasing or stable. It is currently not known if high density concentrations are typically short-lived.

  2. What are the critical features of the habitat, and are they limiting?

    It is not currently known why ribbonsnakes occur in some wetlands and not in others and a suite of habitat features that would predict which habitats are suitable for ribbonsnakes have not yet been identified. It is important to understand how habitat change, connectivity and long-term habitat trends affect persistence of ribbonsnake populations.

    Much remains unknown about overwintering. It is important to know where ribbonsnakes of all life stages spend the winter, identify the characteristics of those sites, determine if sites are used communally or singly and determine if fidelity is shown to specific sites. It is not known if overwintering mortality is a significant threat to the population and have not identified how factors, such as water level fluctuations, affect winter survival.

    It is also not known if ribbonsnakes have specific habitat requirements for other activities (including feeding, basking, mating and gestation/birthing), if sites are used repeatedly over time, or if snakes aggregate at certain sites. The relationship between ribbonsnakes and their prey is not fully understood, and it is not known if there are temporal shifts in prey and feeding locations throughout the season and how significant side pools are as feeding sites.

  3. What are the threats limiting the recovery of this population?

    It is important to identify which threats are the most significant and also the appropriate scale to manage these threats. It is not known how changes in water level, habitat fragmentation, development or climate will affect populations or why the range is limited in the province. Determining if individual concentrations are currently experiencing deleterious effects from small population size (inbreeding, genetic drift, reduced fitness) is necessary to understand factors limiting the population.

    Answering these questions requires basic information on all life stages including basic demography (longevity, stage specific survivorship, population trends, predator and prey relationships), habitat use (sites used for specific life stages, large scale range, habitat characteristics, current movement patterns), and genetic structure (assessment of population structure, evaluation of inbreeding depression, estimate of genetic variation, identification of past events that may have influenced patterns seen today).