Biology session

The Red-footed falcon is a small, colonial raptor species of high national and international conservation concern. These birds are trans-equatorial migrants, wintering in southern Africa. Typically, Red-footed Falcons disperse in the post-breeding period, spending the evenings in –often traditional- common roost sites. Pre-migration habitat use and large scale movements are thought to be highly important in the survival of these birds, as the metabolic reserves enabling successful autumn migration are accumulated in this period. However, little is known on how these birds utilize habitats around roost sites, the location of the roost sites, and on how these birds move in between roost sites. Moreover, only anecdotic and/or empirical information was available on the precise migration routes and wintering grounds of this species. We fitted 8 adult female birds with satellite transmitters (PTTs) to unravel the mystery of pre-migration movements, autumn migration routes and the wintering grounds of Red-footed Falcons. Our primary objective was to use the data of the PTTs to analyse pre-migration movements within the Carpathian basin however, the data enabled us to map out potential roost sites outside the region. Moreover, we were able to assess the extent of the area utilized by one of the birds, spending the bulk of the pre-migration period around one roost site. We were able to determine the autumn migration routes and the wintering grounds of six tagged individuals. We used a Bayesian Trajectory Modelling technique to describe the autumn migration movement patterns of 4 birds. Our results point out 2 and 6 new potential roost sites in Hungary and in southern Ukraine, respectively. The 80% Kernel-home range of a single tracked individual was 73 km2. The trajectory analyses revealed that the Sahara and the Mediterranean Sea is less likely to act as true migratory barriers for these birds, while the speed and movement patterns change within the tropical rainforest biome, indicating that this region is potentially a real obstacle for the falcons. The wintering grounds of the 6 individuals that made it to southern Africa was in the water catchment area of the Okavango, Zambezi, and Cubango Rivers in southern Angola and in northern Namibia.