238 Accipitridae: vultures, kites, hawks, eagles, buzzards and harriers European Marsh Harrier 14˚ Europese Paddavreter EURO. MARSH HARRIER Circus aeruginosus 1 5 As the scattered occurrence on the distribution 18˚ map shows, European Marsh Harriers are rare nonbreeding visitors to southern Africa. They are migrants from the Palearctic and occur mainly over well-vegetated wetlands in the northeastern 22˚ parts of southern Africa. Although they chase large 6 waterbirds, such as ducks, cormorants and egrets 2 which the resident African Marsh Harrier C. ranivorus rarely pursues, their main diet is prob- 26˚ ably small mammals and birds. Most records are of females and immatures, which resemble and may be misidentified as young African Marsh Harriers. They are, however, larger, darker, have 3 7 a cream-coloured and well-defined patch on the 30˚ head (and often shoulders), lack any barring in the plumage and do not have an orange base to the tail. Most records are from November–March. An 4 8 unprecedented number occurred in South Africa in 34˚ the high-rainfall summer of 1987–88: singletons 18˚ 22˚ 26˚ were reported from Bapsfontein (2628AB) and 10˚ 14˚ 30˚ 34˚ Pietersburg (2329CD) (W.R. Tarboton pers. comm.), four from the Kruger National Park (J. van Jaarsveld pers. comm.), and on the flooded Nyl River (2428DA) five were found (Simmons 1988). It is more common in Zimbabwe and Recorded in 62 grid cells, 1.4% further north, however, as these birds probably represent Total number of records: 142 immatures from a distributional tail that spreads south from Mean reporting rate for range: 2.2% Central and West Africa, the main nonbreeding areas. A large roost of ‘several thousand’ birds was recently found in Mali (C. Perennou in litt.). Two records are known for Namibia (not shown), one from the Kuiseb River (2315BC) (L. Komen pers. comm.), and another from Bushmanland, in northeastern 1987b). The recovery of the European Marsh Harrier in the Namibia (Hines 1993). Palearctic is apparently widespread (Del Hoyo et al. 1994); Expansion of some well-monitored populations in Europe, therefore it may become more regular in southern Africa in owing to decreased pesticide abuse (e.g. Underhill-Day 1984; future, particularly in wetter years. The continuing degrada- Altenburg et al. 1987), together with the greater awareness tion of wetlands is the main direct threat to this species in and publishing of rarities in southern Africa, has led to southern Africa. increased reporting in the last two decades (Tarboton et al. R.E. Simmons 2 1 5 1 2 2 6 1 2 3 7 1 Occurrence reporting rate (%) 2 4 8 1 J ASONDJ FMAMJ J ASONDJ FMAMJ Models of seasonality for Zones. Number of records (top to bottom, left to right): Occurrence: 2, 0, 2, 0, 74, 42, 22, 0..