The assessment of artificial cover objects for monitoring the forest indicator species Plethodon cinereus (red-backed salamander).
Chris Sutherland and Evan Grant (adjunct)
The red-backed salamander (Plethodon cinereus) is an important component of the deciduous forest ecosystem because of its ecological role as a vertebrate mid-level detrital predator, but also as an indicator of forest health. As with any surrogate species being used to monitor the health or condition of the larger forest system, it is important that standardized methodologies exist so that comparisons can be made across space and time. Artificial cover objects (ACOs) are a widely-accepted sampling technique used with red-backed salamanders. Although ACOs are often used to sample red-backed salamanders, historically the scale and arrangement of the ACO arrays vary across studies. Moreover, a criticism of the method is that estimates of surface population sizes may be biased high because of the introduction of unnatural amounts of suitable habitat. The lack of any studies directly evaluating the effects of ACO array configuration means it is unclear if biological conclusions from variable ACO array designs can be compared, and furthermore, whether there is an optimal design for surveying red-backed salamanders that minimizes bias and maximizes precision. In this study, I will use a field experiment in Wendell State Forest (Wendell, MA) in which both the sampling area of the ACO array and the ACO density are varied to investigate how ACO configuration influences estimates of salamander density. Over the course of two years, these arrays will be sampled during peak red-backed salamander activity windows in the spring and fall, and individual salamanders will be captured and uniquely marked using visual implant elastomer. Using recently developed spatial capture-recapture methods, density and home range size will be estimated while accounting for imperfect detection. Estimates of density from each ACO arrangement will then be compared to assess whether the ACO array configuration influences the estimates of salamander density. The goal of this project is to assess how array design influences population density and home range estimates of red-backed salamanders, and to make recommendation for the optimal sampling design for this important ecosystem indicator species.