The level, seasonals, and their 95% CI (bands) were estimated using unobserved component time series models (Table 1; Methods). Arrows denote the start of the population growth (text and Fig. 2). Time is shown starting from May to maximize the comparability between the species. In the colour ruler on the x axis, yellow and green denote dry and wet seasons, respectively, and orange and light-green denote transition periods. Sample sizes are given in Extended Data Fig. 1.