This chapter explores the spatial representation of ecological data variables using cartograms. The cartograms are thematic maps that alter the actual geographical dimensions of areas or regions changing their size and shape according to a quantitative variable. Specifically, this chapter describes the use of the R package cartogram to create the main types of cartograms. In this chapter, three functions of the package are described through practical examples that aim to represent the spatial bias associated with the sampling effort of the species observations. We demonstrate the usefulness of cartograms as methods for illustrating the relationships between ecological data and geographic areas, as well as the impact of spatial bias on an ecological variable.