Sea urchin herbivory is a key function in temperate reef ecosystems. Some urchin species overgraze macroalgal forests, leading to their collapse into barren states. In Australia, climate-mediated range extension of urchin species is resulting in increased barrens formation at the cool-edge of their distribution. Despite their ecological importance and association with warming, broad-scale effects of temperature on urchin feeding ecology remain unknown. We characterise in-situ feeding rates of two barrens-forming sea urchin species, one range-extender (Centrostephanus rodgersii), the other range-persistent (Heliocidaris erythrogramma), across 8°C and 12° of their latitudinal distribution, as well as over seasonal cycles. We assess the extent to which potential ecological drivers (temperature, abundance, nutritional value, urchin size/weight) explain patterns in grazing rates. We find contrasting patterns in performance between urchin species across latitude, and a similar response across season. Centrostephanus rodgersii shows a clear peak in grazing in the center of its range, which coincides with a similar peak in abundance. Conversely H. erythrogramma displays no significant change in grazing across latitude. These contrasting patterns suggest each species occupies a different thermal niche, and provide key insights into how the ecological impacts of these species may change across their distribution and in response to ocean warming.