  Understanding human mobility is crucial for a broad range of applications
from disease prediction to communication networks. Most efforts on studying
human mobility have so far used private and low resolution data, such as call
data records. Here, we propose Twitter as a proxy for human mobility, as it
relies on publicly available data and provides high resolution positioning when
users opt to geotag their tweets with their current location. We analyse a
Twitter dataset with more than six million geotagged tweets posted in
Australia, and we demonstrate that Twitter can be a reliable source for
studying human mobility patterns. Our analysis shows that geotagged tweets can
capture rich features of human mobility, such as the diversity of movement
orbits among individuals and of movements within and between cities. We also
find that short and long-distance movers both spend most of their time in large
metropolitan areas, in contrast with intermediate-distance movers movements,
reflecting the impact of different modes of travel. Our study provides solid
evidence that Twitter can indeed be a useful proxy for tracking and predicting
human movement.
