The resistance versus temperature across the metal-insulator transition (MIT) of ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ nanodevices exhibits multiple discontinuous jumps. The jump sizes range over three orders of magnitude in resistance and their distribution follows a power law, implying that the MIT of ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ occurs through avalanches. While the maximum jump size depends on the device size, the power law exponent for ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ is independent of device geometry and different than the one found earlier in $\mathrm{V}{\mathrm{O}}_{2}$. A two-dimensional random percolation model exhibits a power law distribution different from the one found in ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$. Instead, the model gives a similar exponent found in another vanadium oxide, $\mathrm{V}{\mathrm{O}}_{2}$. Our results suggest that the MITs of $\mathrm{V}{\mathrm{O}}_{2}$ and ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ are produced by different mechanisms.