The population dynamics of the Red-footed Falcon (Falco vespertinus) on the southwestern limit of its breeding range

The western boundary of the Palearctic range of the Red-footed Falcon (Falco vespertinus) is located in the Carpathian Basin, with significant breeding areas in the northern part of Serbia, Voivodina Province. The size of the breeding population has been estimated and surveyed several times since the middle of the last century. The number of breeding pairs showed considerable variation, while estimates suggested a declining trend in the population size, though the dynamics of the Red-footed Falcon population was less known. This motivated us to perform censuses every year from 2000 until 2009. During that period, the number of confirmed breeding pairs varied from 61 to 179. We found that the number of breeding pairs decreased significantly (˃ 40%) after a 3-4 year of increase. The number of breeding sites and the extent of the distribution area changed in proportion to the increase or decrease of the population size. However, the change in population size was unrelated to the general proportion of pairs breeding in colonies (87–96%) and those breeding solitarily (4–13%).