Little is known about the distribution, ecology and behaviour of hummingbirds in the Andean foothills of Bolivia, where many lowland hummingbird species reach their south-western distributional limits. In November
2007 – October 2008, we surveyed hummingbirds at six sites along a 660-km transect, from tropical Amazonian humid forest to subtropical spiny forest of the Gran Chaco. In total, we found 21 hummingbird species. For ten of these, we provide new information on latitudinal and elevational movements, feeding or breeding behaviour. In particular, we provide evidence for seasonal movements of five species, including such widespread taxa as White-chinned Sapphire Hylocharis cyanus and Fork-tailed Woodnymph Thalurania furcata, which are considered sedentary throughout most of their ranges, but which appear to undergo seasonal movements at their range limits in Bolivia.