Using decades of data, a recent study analyzed long-term population trends for the Mauritius kestrel, a bird of prey endemic to the island of Mauritius, which was once considered the rarest bird in the world. .While an intensive recovery program for the kestrel helped increase the population to an estimated 400 individuals by the 1990s, scientists now estimate there are fewer than 250 in the wild. .They link this decline to a halt in monitoring efforts, which occurred, ironically, ...