Population size of the Common Quail Coturnix coturnix at Ljubljansko barje decreased in the last twenty years by half, perhaps even (much?) more

In 2015, we used the same method as in the 1989-1996 period to count calling males of the Common Quail Coturnix coturnix in selected 1x1 km squares of Ljubljansko barje (central Slovenia). We counted 39 males, which is 87% less compared to the survey 20 years ago. Quails were found in 56% fewer squares. Since Quail populations are known to fluctuate greatly between years, we think that the most realistic long-term estimate for population decline would be somewhere between 50 to 90%. We detected that within only one week males stopped calling in some squares, while in others they began calling although they had not been detected there before, indicating possible relocations. This dynamics should be considered when designing a population monitoring protocol for the Quail.