Figure 4 in Genetic and morphometric variation of the Blackcap (Sylvia atricapilla) on the Azores Archipelago reveals a recent range expansion

Figure 4. Bayesian skyline plot showing changes in effective population size through time (million years ago). Estimations were based on a molecular clock of 2% divergence for one million years. The population size and the generation time is reported on the y-axis. Estimates of means are joined by a solid line; whereas clear lines mark the 95% highest probability density limits.