Priority sampling locations in the U.S., Canada, and Mexico for the Integrated Monarch Monitoring Program

The sampling locations provided here were selected as a two-stage Generalized Random Tessellation Stratified (GRTS) sample (Stevens & Olsen 2004). The first stage of the GRTS draw used a master sample developed by the North American Bat Monitoring Program (Loeb et al. 2015) from a 10 x 10 km grid placed over the conterminous U.S., Canada, and Mexico. Each 10 x 10 km grid cell (hereafter, master cell) was assigned a GRTS rank by NABat. The rank represents the priority order in which master cells should ideally be sampled. For the second stage of the draw, sampling points within a master cell were selected. Each point was defined as a 30 x 30 m cell of the GIS raster that defined monarch-relevant habitat. Sampling points within each master cell were assigned to 5 land-use sectors of interest. For the western U.S., 3 categories of estimated milkweed habitat suitability were used instead of land-use sectors.