Open Access Thesis
Master of Science (M.S.)
Year Degree Awarded
Month Degree Awarded
The red-backed salamander (RBS; Plethodon cinereus) has a large geographic range and,
though it is common throughout, abundance varies spatially. It has been studied extensively for at
least a century and as a result; its distribution, habitat use, behavioral ecology, reproductive
ecology, and ecological role are well understood in comparison to other cryptic wildlife. Multiple
sampling methods have been developed to monitor RBS, and I discuss in detail one common
method – artificial cover objects (ACOs). Spatial capture-recapture (SCR) is uniquely suited to
estimate population parameters, including true density, and is paired well with spatially
referenced sampling methods, such as ACOs, and animals capable of retaining unique marks,
such as RBS. In the introduction of this thesis, I review RBS, ACOs, and SCR independently in
detail, and go on to discuss their compatibility for monitoring terrestrial salamander populations.
Detailed, and often range-wide, monitoring of ecosystems is necessary to gather the
information needed to achieve broad multiple-scale conservation objectives. Indicator species are
recommended tools for filling in gaps of knowledge where these range-wide data do not exist.
The use of indicator species is precluded by the lack of evaluation of candidate indicators and
their relationship to indicated processes. In this thesis, I discuss in detail the practicality of
indicator species as wildlife management tools, and challenges in their application – primarily
their practicality when direct measurement of a variable of interest is possible. I advocate for
integrative indicator species applications that make use of relationships to latent variables, review
two conceptual models involving latent variables, and propose a modification to these models that
makes relationships between variables more explicit.
Inference of among-population variation to adaptive capacity, response to large-scale
threats, and the condition of ecosystems is limited in part by unstandardized methods. Ecological
relationships are made difficult to characterize by gaps in data - and this is especially true of links
between indicator species their and related ecosystem processes. Using a candidate indicator
species, I tested the congruence of population parameter estimates from study designs that varied.
In Wendell State Forest, MA, I manipulated spatial arrangements of artificial cover objects
(ACO) arrays and evaluated their use for monitoring terrestrial salamanders. ACOs mimic natural
habitat - and attraction of RBS to traps may induce behavioral bias in parameter estimates if not
accounted for. I sought to determine if variation in ACO design can be accommodated to make
comparable estimates. I found that analyzing data from ACOs using spatial capture-recapture
(SCR) modeling produces consistent within-population density estimates regardless of ACO
Fleming, Jillian, "You Must Estimate Before You Indicate: Design and Model-Based Methods for Evaluating Utility of a Candidate Forest Indicator Species" (2018). Masters Theses. 705.