  In this article, a model, discrete in space and time, is developed to
describe the growth and spread of the Scottish populations of red squirrels
(Sciurus vulgaris) and grey squirrel (Sciurus carolinensis). The initial state
for the model is designed using a large dataset of records of sightings of
individuals of both species reported by members of the public. Choices of
parameters involved in the model and their values are informed by the analysis
of this dataset for the period 2011-2016, and model predictions are compared to
records for the years 2006-2019.
