Habitat Suitability, Occupancy, and a Novel Monitoring Technique for an Imperiled Reptile

摘要

Reptile species and populations are declining globally. Habitat destruction, degradation, and fragmentation are important factors leading to this global decline of reptiles. Therefore, protection and restoration of key habitat for reptiles is particularly important for their conservation. Long-term monitoring studies are crucial for the conservation of rare and imperiled reptiles, such as the Copper-Bellied Watersnake (Nerodia erythrogaster neglecta). The Northern population segment of this snake is federally listed as threatened and is endangered in Indiana, Ohio, and Michigan, where it occurs. Several years ago this population was estimated to have a maximum of 116 individuals, and the population is declining.Data collected during this study will be used to formulate habitat suitability index (HSI) models to quantitatively assign conservation value to different habitat patches in the area based on their suitability for copperbellies. HSI modelling is a procedure developed by the US Fish and Wildlife Service in which model outputs fall between 0 (totally unsuitable habitat) and 1 (optimum habitat with maximum carrying capacity).Habitat and occupancy data collected during this survey and occupancy data from previous years will also be used to formulate occupancy models which are useful for making predictions about which habitat patches copperbellies are likely to inhabit, based on presence-absence data, detection probabilities, and habitat characteristics such as wetland area, vegetation type, and presence of prey and competitors. Occupancy can be defined as the fraction of habitat patches where a species is present. Measureable habitat characteristics can be factored into occupancy models as covariates affecting presence or absence of a species. These occupancy models can also be used to determine how many survey visits are required to a site before it can be determined with statistical confidence that the species is not present, rather than undetected, at the site.I will also utilize artificial basking platforms and wildlife cameras to determine if this novel surveying approach is viable as a snake-monitoring technique to replace or be used in conjunction with visual encounter surveys, which are often costly, time-consuming, and require great effort by observers trekking through difficult terrain. If I find this novel monitoring approach to be viable as a surrogate for visual encounter surveys, it might replace these types of surveys for future copperbelly researchers in order to save time, money, and effort.This research will be to fulfill the thesis requirement of a Master’s degree at IPFW. The results will provide valuable information about copperbelly habitat requirements and population status, in addition to testing out new monitoring techniques, and as such will be useful for conservation efforts for this rare reptile.