564 Cuculidae: cuckoos and coucals conditions and the timing of breeding Diederik Cuckoo of hosts, and may consequently differ Diederikkie between years and according to which host species contributes most to the Chrysococcyx caprius data set. Interspecific relationships: 24 The Diederik Cuckoo is common and host species are known, with Cape widespread throughout the Afrotropics Sparrow Passer melanurus, Masked and occurs in the savanna and forest Weaver Ploceus velatus, Cape Weaver areas from West to East Africa, and P. capensis, Spottedbacked Weaver P. over most of southern Africa (Fry et al. cucullatus, Red Bishop Euplectes orix 1988). There are strongholds in Kwa- and Cape Wagtail Motacilla capensis Zulu-Natal and most of the Transvaal being most frequent (Maclean 1993b). and adjacent hardveld in eastern Bot- Most hosts start breeding well before swana; reporting rates drop sharply Diederik Cuckoos arrive on the breed- further west on Kalahari sands. It is ing grounds and their earlier clutches absent from the Lesotho highlands and are free from nest parasitism. thinly reported from the Transkei. It is The Diederik Cuckoo is ecologi- scarce in the more arid parts of the cally separated from the Emerald Kalahari and the interior of the west- Cuckoo C. cupreus, but overlaps with ern Cape Province; it is absent from Klaas’s Cuckoo C. klaas. Although the Namib Desert. both eat caterpillars, they have differ- It is one of the most conspicuous ent brood hosts and no instances of cuckoos and the atlas data are compre- interspecific competition have been hensive. Its name is onomatopoeic for recorded (Rowan 1983). the energetic territorial call of the Historical distribution and con- male, and most atlas records would have been identified on servation: Although there is no specific evidence, it is likely vocalization. that it has expanded its range during the 20th century, mainly Habitat: It occurs in a variety of habitats, from the forest because of the planting of alien trees, and by indirect promo- edge to semi-desert (Fry et al. 1988). It is not usually found tion of its granivorous hosts. It has increased in abundance in in forest and is uncommon in Mopane woodland, but other- the southwestern Cape Province in the past decades; this has wise is tolerant of a wide range of woodland habitats (Rowan been attributed to an increase in the abundance of its hosts 1983). (Hockey et al. 1989). The Diederick Cuckoo is not threatened. Movements: It is an intra-African migrant; first arrivals are in September, while most rapid arrival is during October over C.J. Vernon and M. Herremans the core of the range (Zones 4–8); in the drier western regions (Zones 1–3), arrival is on average about a month later, prob- ably dependent on the onset of the rains. The data confirm Recorded in 2257 grid cells, 49.7% published information on arrival (Rowan 1983; Tarboton et Total number of records: 24 915 al. 1987b; Hockey et al. 1989; Maclean 1993b; Herremans Mean reporting rate for range: 19.3% 1994d). The period of presence, as indicated by vocalizations, decreases southwards. In Zimbabwe (Zone 5) it calls for about six months, while it stops calling at the end of January in the Reporting rates for vegetation types southwestern Cape Province (Zone 4) where it calls for only % 0102030 about three months (Rowan 1983; Hockey et al. 1989). Most adults may leave the breeding grounds by late February Sweet Grasslands 26.7 (Maclean 1993b), but evidence from late-hatching chicks Moist Woodland 25.9 indicates that some do so only by late April, at least in some Sour Grasslands 23.7 years (Rowan 1983). The latest birds of the season are mostly Mixed Grasslands 22.6 juveniles (Rowan 1983; Tarboton et al. 1987b). Atlas records Miombo 21.1 confirm that it very occasionally overwinters in southern Arid Woodland 20.3 Africa (Rowan 1983; Earlé & Grobler 1987; Tarboton et al. Central Kalahari 18.4 1987b). Grassy Karoo 18.0 Breeding: Egglaying by this brood parasite spans October– E Zimbabwe Highlands 17.8 April (Dean 1971; Irwin 1981; Rowan 1983; Tarboton et al. Valley Bushveld 17.6 1987b; Skinner 1996a; Brown & Clinning in press), peaking East Coast Littoral 16.6 progressively later from south to north: November in the Cape Mopane 13.5 Province, December in KwaZulu-Natal and the Transvaal, Nama Karoo 11.9 January in Zimbabwe, and February in Namibia and Bot- Okavango 9.7 swana (Rowan 1983). Namibian Escarpment 9.0 Atlas records are biased towards later dates because Northern Kalahari 8.2 fledged young are the most conspicuous signs of breeding, but Fynbos 5.7 they confirm that most breeding takes place November–April, Alpine Grasslands 5.6 with a December–January peak. Breeding in the most arid Southern Kalahari 5.5 region (Zone 2) is clearly later than in other regions. The fine- Succulent Karoo 3.9 tuning of breeding seasonality may be dependent on veld Namib 1.6 Cuculidae: cuckoos and coucals 565 14˚ DIEDERIK CUCKOO 5 1 18˚ 22˚ 2 6 26˚ 3 7 30˚ Reporting rate (%) > 23.9 12.6 — 23.9 2.0 — 12.5 < 2.0 34˚ 4 8 18˚ 22˚ 26˚ 14˚ 30˚ 10˚ 34˚ 60 40 40 1 5 20 20 60 40 40 2 6 20 20 60 40 40 3 7 20 20 60 40 Occurrence reporting rate (%) Breeding reporting rate (%) 40 4 8 20 20 J ASONDJ FMAMJ J ASONDJ FMAMJ Models of seasonality for Zones. Number of records (top to bottom, left to right): Occurrence: 183, 186, 352, 437, 1510, 2395, 3841, 565; Breeding: 5, 23, 37, 28, 22, 127, 209, 28..