Fig 4. Relationship between calving synchrony of a reindeer population in northern Finland and (a) the mean temperature in January, (b) the cumulative snow depth indexes in the period from October to November, (c) the number of days when mean temperature exceeds 0°C in October-November, and (d) the SDI in November.

The 95% confidence interval band around the fitted line is provided. The climatic data from October to November were from the calendar year preceding the year of the calving synchrony whereas the climatic data for January were from the same calendar year as calving synchrony. The calving synchrony was expressed in number of days as reflecting the length of the calving season. The cumulative SDI was the sum of the snow depth indexes for the period of interest.