The practical engineering plausibility of transmission-loss inversion methods using low-cost sensor network technologies for location and tracking of small ruminants is investigated experimentally. Transmission loss is measured in representative outdoor environments using IEEE 802.15.4 technology. The simplest possible propagation model is shown to reflect the general features of the measured propagation data. Its absolute accuracy, however, is probably inadequate for use in a location algorithm based on model inversion without optimization of its parameters. Model calibration to reflect inter-site variation of the propagation environment is suggested as a possible way of realizing a location system with useful accuracy and adequate portability.