A species' distribution can be characterized by the probability that it occurs at some location in space. Estimating occurrence probability can be easily accomplished using presence-absence data, but often researchers only have presence locations and environmental data for the study area. MAXENT is a popular software program for modeling species distributions, but it does not estimate the probability of occurrence. Rather, it returns various indices that are not easy to interpret (see Royle et al. 2012). Package "maxlike" provides a simple likelihood-based alternative.
J. A. Royle, R. B. Chandler, C. Yackulic and J. D. Nichols. 2012. Likelihood analysis of species occurrence probability from presence-only data for modelling species distributions. Methods in Ecology and Evolution 3:545--554. doi: 10.1111/j.2041-210X.2011.00182.x.
maxlike, raster