Survey techniques for determining distribution, abundance, and occupancy of the carnivore guild in the Apostle Islands National Lakeshore (2014-2017)

Abstract

from all three groups contributed to the study design, along with placement and maintenance of camera traps. Researchers at the University of Wisconsin provided statistical analyses and reporting, and will ensure that results will be published in peer-reviewed journals.We thank the personnel from each group that contributed to this project, especially APIS staff and volunteers, graduate students from the Van Deelen lab at the University of Wisconsin -Madison, and students from Northland College that provided assistance over the course of the project. The support and cooperative spirit between these three groups was key to the success of this project.PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.26835v1 | CC0 Open Access | rec ABSTRACTCarnivores are important components of ecosystems with wide-ranging effects on ecological communities. These wide-ranging effects are complex and vary with carnivore size, natural history, and hunting tactics, and researchers and managers must understand the ecological roles of carnivores and their interactions with their local environment. We studied the carnivore guild in the Apostle Islands National Lakeshore (APIS), where the distribution, abundance, and occupancy of carnivores was largely unknown. This knowledge was needed to understand islandlevel variation in carnivore communities and how this variation affects the community-level ecology of APIS. We developed a systematic method to deploy a grid of camera traps while targeting fine-scale features to maximize carnivore detection (Appendix 1) and for organizing and tagging the resulting photograph data (Appendix 2).In this report, we document our findings from deploying 160 camera traps on 19 islands and mainland Wisconsin from 2014-2017. We collected 203,385 photographs across 49,280 trap nights, with 7,291 total wildlife events and 1,970 carnivore events. We had a mean 7.68 functioning camera traps per island (range 1-30), and our camera trap density averaged 1.89 (range 0.75-12.50) camera traps/ km 2 . We detected 10 terrestrial carnivores among 21 unique species detected, including unanticipated detections of American martens (Martes americana) and gray wolves (Canis lupus). The mean richness of carnivores on an island was 3.10 (range 0-10) species/island. The most supported single variable to explain carnivore richness on the Apostle Islands was island size, while the most supported model was island biogeography, which included island size (positive correlation), distance to mainland (negative correlation), and distance to nearest island (negative correlation). The relative abundance of a species was significantly correlated with the number of islands on which they were found. Mean carnivore occupancy across islands ranged from 0.24 for gray wolves to a high of 0.93 for black bears (Ursus americanus).Detection rates for species were generally higher in summer than winter, with the exception of coyotes (Canis latrans) and red foxes (Vulpes vulpes). Allen et al. 2017 -Apostle Island Carnivore Guild Low levels ...