How Many Azores Bullfinches Are There in the World? Case Study of a Threatened Species

The Azores bullfinch (Pyrrhula murina Godman, 1866) is a rare Passeriformes endemic from the eastern part of São Miguel Island. This bird was almost considered extinct in the first half of the 20th century and, due to recent conservation measures, it has experienced a recovery since the beginning of the 2000s. Despite the attention given to this bird, the size of its population is still controversial, and the most recent studies present significant divergences on this behalf. The pur-pose of the present study is to present data from the long-term monitoring of the Azores bullfinch to update the information about the population size and range of this species. In addition, we performed a literature review to highlight the limitations and advantages of the different ap-proaches for monitoring this species. In this study, we conclude that the most likely size of the Azores bullfinch population is 500 to 800 couples, with a slow population growth tendency, and an area of distribution of 130 Km2.