SYMP 17-2
A mammal's tale: Fine scale trapping events over time

Thursday, August 8, 2013: 8:30 AM
205AB, Minneapolis Convention Center
Allyson Degrassi, Department of Biology, University of Vermont, Burlington, VT

Fine spatial and fine temporal scale studies can provide retrospective assessments of small mammal population dynamics. A considerable amount of information can be extracted from conducting long-term studies using capture-mark-recapture methods on small trapping grids (< 100 m2 area). Examples of fine scale population and community dynamics will be primarily taken from a project currently in progress on the small mammal fauna at Harvard Forest Hemlock Removal Experiment (HF-HeRE) plots. To understand how small mammal composition differs among forest treatments, I am conducting a 3 year (2012-2015) grid based survey of rodent communities on fine temporal (< 24 days) and spatial (<70m2) scales. Sampling grids, consisting of 49 Sherman live-traps and covering 0.49ha, were established within each plot in May 2012 and will be resampled from June-August.


At the site level, the state of occupancy at a trapping location, microhabitat associations, and the probability of capture for location can be estimated. Robust estimates of species detection probability can be used to address questions about species habitat associations and dispersal. At the population level, survivorship, local colonization, and local extinction can be estimated on a daily, weekly, monthly, and annual basis. Information can be used in building population viability analysis (PVA) models that estimate population persistence. At the community level, species richness, evenness, interspecific interaction, and patterns of co-occurrence can be estimated. This talk is on the techniques used to investigate fine scale population and community dynamics with respect to sampling approaches and replication procedures. I will primarily focus on literature and examples from capture-mark-recapture studies to address 1) the validity of site, population, and community level data, 2) the strength of fine scale approach to population and community dynamics, 3) what diverse questions can be answered and addressed using fine scale approach, and 4) how fine scale methods can be used to draw conclusions about population and community dynamics in locally changing environments, which may inform conservation and management programs.