When does weather synchronise life history traits? Spatiotemporal patterns in juvenile body mass of two ungulates

1. Theory predicts that animal populations will be synchronised over large distances by weather and climatic conditions with high spatial synchrony. However, local variation in population responses to weather, and low synchrony in key weather variables or in other ecological processes may reduce the population synchrony. 2. We investigated to what extent temperature and precipitation during different periods of the year synchronised juvenile body mass of moose and reindeer in Norway. We expected high synchronising effect of weather variables with a high and consistent explanatory power on body mass dynamics across populations, and a weaker synchronising effect of weather variables whose effect on body mass varied among populations. 3. Juvenile body mass in both species was related to temperature and precipitation during several periods of the year. Temperature had the strongest explanatory power in both species, with a similar effect across all populations. 4. There was higher spatial s...