Short Communications Breeding Success of Three Wader Species In
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Short communications 1 Short communications Breeding success of three wader species in suburban areas of the Western Cape, South Africa K.M.C. TJØRVE* Avian Demography Unit, Department of Statistical Sciences, University of Cape Town, Rondebosch 7701, South Africa. [email protected] A large diversity of bird species, particularly passerines and servation. I therefore monitored the breeding success of some columbidae, have been associated with gardens and Blacksmith and Crowned Lapwings and Spotted Thick-knees parks of Europe for centuries (Lancaster & Rees 1979, Toms in the Western Cape, South Africa, in an attempt to determine 2003). The garden bird avifauna in the suburbs of Cape whether these suburban populations are capable of maintain- Town, Western Cape, South Africa, is depauperate in com- ing themselves. parison. Species are, however, slowly adapting to these trans- The study was conducted from May 2001 to April 2004. formed habitats, and novel garden species are regularly Nine different study sites were monitored within the subur- reported. Shorebirds have started to occupy transformed habi- bia of Cape Town and Somerset West, approximately 50 km tats in suburbia in South Africa including golf courses, play- from Cape Town: Claremont Primary School, Diocesan ing fields, and other open areas with short grass. In its pristine College, Red Cross Hospital and University of Cape Town state, these areas would mostly have consisted of lowland rugby field and cricket oval, Kenilworth Race Course, fynbos, a scrub vegetation less than 1 m tall (Acocks 1953), Erinvale Golf Estate, Mowbray Golf Course and Pinelands but totally unsuited to the species currently occupying them. Golf Course. Monitoring at Red Cross Hospital and Diocesan Consequently, some shorebird species are probably more College occurred over three breeding seasons; other sites common in the urbanized areas of the greater Cape Town were monitored for two breeding seasons. region now than they were a century ago. In contrast, shore- Nests were searched for regularly and, once found, moni- birds are seldom observed in equivalent transformed habitats tored at 3–4 day intervals until hatching. Chicks were simi- in Europe. larly monitored, every 4–7 days, until fledging. Fledging was Blacksmith Lapwings, Vanellus armatus, Crowned Lap- taken as the day from which chicks are able to fly well and wings, V. coronatus, and Spotted Thick-knees, Burhinus this occurs around the age of five weeks (with some variation vermiculatus are three shorebird species that have a wide between species), when the chicks are about two-thirds of breeding distribution in southern Africa and are found in adult body mass. All chicks and most adults in the study suburban areas in the Western Cape (Harrison et al. 1997, populations were ringed with individually numbered metal Hockey et al. 2005). These species have different breeding leg bands and a unique combination of coloured leg bands. periods: Blacksmith Lapwings breed from April to October Breeding success was determined for all three species at whilst Crowned Lapwings and Spotted Thick-knees breed the nine sites (Table 1). Sixteen clutches from nine pairs were from September to April (Harrison et al. 1997, Hockey et al. monitored in the 2001–2002 breeding season; 48 clutches 2005). Blacksmith and Crowned Lapwings prefer to nest in from 24 pairs in the 2002–2003 breeding season and 109 short grass, the former mostly near water on river or dam clutches from 98 pairs in the 2003–2004 breeding season. banks and the latter in drier habitats (Hall 1959, Skead 1955, Breeding success (fledglings per egg) were approximately the Ward 1997, Ward et al. 1997). Spotted Thick-knees choose same for the three study species. The number of fledglings to nest in the leaf litter near bushes or under trees (Maclean per pair was lower for Spotted Thick-knee (0.64) than for 1997, Skead 1995). Due to the spread of suburbia these spe- Blacksmith (1.51) or Crowned (1.35) Lapwings. Over the cies have changed their choice of nesting habitats and are now three years, there was little variation in the annual number of found in suburban areas, such as school grounds, golf courses, fledglings per egg laid in Spotted Thick-knees (0.32–0.34) suburban gardens and even curbsides. and rather more variation in Blacksmith and Crowned Lap- Breeding attempts in suburbia are at risk of disturbance by wings (0.29–0.68 and 0.23–0.63 respectively). There was no sporting events, people walking their dogs, children playing obvious trend in breeding success in the three study species. and other human activities. This disturbance may result from Lapwings and thick-knees breeding in urban areas most the lack of public awareness about breeding birds and how likely experience more disturbance than birds breeding in to respond to them. In addition to human disturbance birds more natural environments. This may make their breeding breeding in suburbia are subject to predation by domestic attempts more vulnerable to predation. Potential predators animals and other more natural predators like crows or gulls include crows, gulls, domestic dogs and domestic and feral (pers. obs). Despite the proximity of these suburban waders cats. Lapwing and thick-knee chicks are precocial so chicks to humanity, very little is known about their population size leave the nest soon after hatching (Hockey et al. 2005). Lap- and breeding success, data which are essential for their con- wing chicks are able to feed themselves shortly after leaving *Current address: Lista Bird Observatory, Research Group, Fyrveien 6, N-4563 Borhaug, Norway. 1 Bulletin 111 December 2006 2 Wader Study Group Bulletin Table 1. Breeding success in suburban habitats of Blacksmith Lapwing, Crowned Lapwing and Spotted Thick-knee in the Western Cape, South Africa, during the 2001–2002, 2002–2003 and 2003–2004 breeding seasons. Species Breeding season Study sites Nests Breeding pairs Eggs Breeding succes: fledglings per pair per egg Blacksmith Lapwing 2001–2002 1 1 1 3 0* 0* 2002–2003 2 7 7 22 2.14 0.68 2003–2004 6 58 57 172 0.88 0.29 Totals/average annual breeding success 9 66 65 197 1.51 0.49 Crowned Lapwing 2001–2002 2 9 5 16 2.00 0.63 2002–2003 3 22 8 43 1.25 0.23 2003–2004 4 20 15 31 0.80 0.39 Totals/average annual breeding success 9 51 28 90 1.35 0.42 Spotted Thick-knee 2001–2002 2 6 3 12 0.13 0.33 2002–2003 5 19 9 36 1.11 0.32 2003–2004 7 31 26 53 0.69 0.34 Totals/average annual breeding success 14 56 38 101 0.64 0.33 * The failure of this one nest in 2001–2002 is omitted from calculation of average annual breeding success. the nest whereas Spotted Thick-knee chicks, although mobile, cat populations. are not capable of catching and handling prey being parent- This note highlights the significance of suburban areas as fed until fledging (Hockey et al. 2005). Precocial shorebird breeding sites for three wader species in South Africa. Fur- chicks attempt to evade predators by hiding motionless, ther studies are required to determine the size of their depending on their camouflage (del Hoyo et al. 1996) but this populations and their breeding success in other habitats. strategy does not seem to work well on the frequently mown This research was supported by the Centre for Isotope grass of fields, golf courses and gardens. Research at the University of Groningen, the Darwin Initia- At Diocesan College, dogs and cats roam the property day tive, the Earthwatch Institute, the National Research Founda- and night and thus have a large impact on breeding Spotted tion, the University of Cape Town, the Association for the Thick-knees. As a result, most chick losses at this location Study of Animal Behaviour and the South African Network were due to predation. Only one chick was lost because of for Coastal and Oceanographic Research. Claremont Primary human activities: it was been trampled during a cross-coun- School, Diocesan College, Erinvale Estate, Mowbray Golf try race when only a few days old. At Red Cross Hospital, Course, Red Cross Hospital, and Strand Golf Course pro- there were two feral cats which were fed five days a week, but vided access to study sites. All the field workers involved in left to fend for themselves over weekends. They are likely to this project are thanked for their assistance, in particular have had an impact on the waders breeding there. Derek and Merle Chalton, Margot Penstone, Gordon Scholtz From unpublished data (which could be from either sub- and the late Manfred Waltner. Les Underhill and Pedro urban or natural habitats), Hockey et al. (2005) estimated Lourenco are thanked for their comments. Blacksmith Lapwing hatching success at 87% and fledging success at 26%. This study shows that breeding success in Acocks, J.P.H. 1953.Veld types of South Africa. Memoirs of the Botani- terms of number of fledglings per egg laid was similar at cal Society of South Africa 28: 1–128. about 35%. There are no records of the breeding success of Calf, K.M. & Chalton, D. 2002. Multiple clutches in a single season – Dikkops ensuring breeding success in triplicate. Promerops 252: 13. Crowned Lapwings and Spotted Thick-knees in the literature. Hall, K.R.L. 1959. A study of the Blacksmith Plover Hopolopterus The breeding season of all three species is long and sev- armatus in the Cape Town area: I Distribution and breeding data. eral replacement clutches may be laid if eggs or chicks are Ostrich 30: 117–126. lost. In addition, they are capable of fledging chicks from Harrison, J.A., Allan, D.G., Underhill, L.G., Herremans, M., Tree, several clutches in a single season (Calf & Chalton 2002).