Interpretation of cat maps: The GPS units used in this study need to access signals from multiple satellites to determine their location. GPS data-points with strong satellite coverage are typically accurate to around 10 metres. However, when cats are indoors, or underneath dense cover, the units often get poor satellite coverage, resulting in spurious GPS fixes. Data from the GPS units are filtered before they are put online. This process removes data-points that the GPS units flag as suspicious. We also run a speed filter to remove data points that are unlikely. For example, the speed filter will detect and remove data-points if a cat is taken for a drive in a car. Additionally, the straight lines between the data-points may not necessarily display the exact path the cat took, but simply connect GPS consecutive points where the cat was recorded.