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The regional population of Lanner Falcon Falco biarmicus appears to be decreasing at a rate that satisfies the population-trend criterion for regionally Vulnerable (greater than 30% decline over 10 years or three generations). In addition, the species qualifies for regionally Vulnerable under the population-size criterion (less than10 000 mature individuals, with a continuing decline estimated to be greater than 10% over three generations).
The Lanner Falcon is widespread across Africa, the Arabian Peninsula and the Western Palearctic (Ferguson-Lees and Christie 2001). Within the region, the species occurs widely but sparsely throughout South Africa, Lesotho and Swaziland, with the highest densities recorded in Western Cape and KwaZulu-Natal. The species is a partial seasonal migrant, and there is a post-breeding exodus from the core breeding range in the eastern sour grasslands (December-January), with apparent movements westwards in the non-breeding season into Fynbos, Nama Karoo and southern Kalahari, returning May-June (van Zyl et al. 1994). Movements may be more variable and nomadic in character, and are probably related to rainfall and consequently prey abundance. The species has been able to take advantage of existing corvid nests on transmission poles in the Karoo, enabling it to inhabit large expanses of otherwise treeless habitat (Jenkins 2000b). Comparison of SABAP1 and SABAP2 data between 1997 and 2015 indicates that the species has undergone a c. 40% decline in AoO. While the relationship between a decline in AoO and sparsely distributed species has not been verified it does indicate that the Lanner Falcon may have undergone a decline. The species is well represented in the regional Important Bird Areas network.
The global population has not been quantified (BirdLife International 2014bd) although Ferguson-Lees and Christie (2001) estimated at least 65 000 pairs. Cade and Digby (1982) estimated that 9 000-18 000 pairs occur in the region, while Tarboton and Allan (1984) estimated 1 400 pairs in the former Transvaal. These population estimates are now almost certainly out of date and overly optimistic. Barnes and Jenkins (2000) did not provide a population estimate in their 2000 assessment of the species. A preliminary estimate of less than5 000 mature individuals in the region is provided here, although confidence in this figure is low.
The global population has suffered local declines (BirdLife International 2014bd). Between 1997 and 2013, the species has apparently undergone a considerable (c. 40%) decline in AoO. As Lanner Falcons are territorial and relatively conspicuous, the species is unlikely to have been under-recorded in SABAP2. Assuming that the population in 1997, three generations ago, was in the region of 13 500 mature individuals, and that the decline was exponential, this would represent a decrease of 45% over three generations. This is a conservative estimate and is based upon the assumption that the population was stable between 1982 and 1997; this is unlikely to have been the case, particularly in agricultural landscapes (Kemp 1993). Confidence in the estimate is low.
The primary threat to the Lanner Falcon is the loss or transformation of habitat within the Grassland Biome, through urbanisation, agriculture and afforestation, with corresponding reductions in preferred prey and foraging opportunities (Barnes and Jenkins 2000). To some extent, these processes may be offset in woodland and forested areas where the clearing of trees serves to enhance existing conditions or even create additional habitat. Secondary threats include poisoning by agrochemicals (Kemp 1993), collisions with power-lines, and persecution by pigeon fanciers and owners of domestic fowl (which in some areas make up 30-40% of their diet; Leonardi et al. 1992).
No species-specific actions are currently underway.
Conservation measures must focus on identifying and legally protecting key sites and preserving suitable habitat, as well as the promotion of policies for reduction in use of pesticides. A Species Action Plan is recommended. Options for minimising motivation for direct persecution by poultry farmers and pigeon owners should be investigated.
* An accurate estimate of the regional population and its trends is needed, especially for the breeding versus non-breeding densities in different seasons and habitats.
* The disappearance of the Lanner Falcon from areas of the country has apparently been coincidental with the expansion of the Peregrine Falcon, F. peregrinus into those same areas (e.g. parts of Mpumalanga, KwaZulu-Natal and Eastern Cape). Research into the drivers of these contrasting trends may be key to understanding the true status of the Lanner Falcon in the region.