Existing community science programs like eButterfly and Mission Monarch help to address knowledge gaps by providing relevant data regarding monarch and milkweed distribution. However, participants of those programs often visit high-quality habitats where monarchs are expected to be observed, as well as locations close to human population centres, creating bias in the data. Indeed, butterfly surveys conducted in high-quality patches overestimate butterfly abundance. Low-quality habitats with fewer or no milkweed plants or monarchs must also be sampled to avoid such bias. Therefore, spatially balanced surveys stratified by land cover types are needed to detect long-term changes in populations and habitats.
The MMx Sampling Grid, strongly inspired by the Generalized Random Tessellation Systematic (GRTS) sampling framework used by the Integrated Monarch Monitoring program (IMMP) in the US, was designed to address those bias by collecting robust and representative data, across land uses and geographies in Canada, on monarchs and their habitats.
Therefore sites were randomly selected at two levels. First, 10 x 10 km grid squares (hereafter, Blocks) were placed across Canada and randomly numbered. Second, thousands of points (hereafter, Sampling Points), within the randomly selected blocks, were also randomly selected.
For further details on the design of the MMx Sampling Grid, please refer to the Appendix B of the Canadian Monarch Monitoring Protocol & Sampling Grid.
