Bird migration in the Americas. Animation of a global map showing the migration patterns of birds in the Americas. This dataset shows the migration of 118 species of terrestrial bird populations. Each dot represents the estimated location of the centre of each species' population for each day of the year. These estimates come from millions of observations from the eBird citizen-science database. The colours in this dataset represent the average daily air temperature at the surface, calculated from observations from 1981-2010. The yellow and red colours represent warmer air, while blue colours show areas where the air temperature is below freezing.