636 Viduidae: whydahs and widowfinches

lations in the moist southern and eastern parts of the region may have a greater proportion of resident individuals than those in the arid northwest. Breeding: Breeding depends on the activity of its host, normally the Common Waxbill Estrilda astrild. It breeds in spring and summer (mainly August–May), but breeding peaks earlier (October–December) in the winter-rainfall area in the southwestern Cape Province (Zone 4) than further north in the Transvaal (January–February) or Zimbabwe (January– March), corroborating published egglaying data (Winter- bottom 1968a; Irwin 1981; Tarboton et al. 1987b). Breeding was not recorded from the northwest of the region (Zones 1 and 2) (see also Skinner 1995a; Brown & Clinning in press). Interspecific relationships: It is the only viduid finch in the region which lacks a strictly host-specific relationship with a single estrildid finch. Although it nearly always para- sitizes the Common Waxbill in southern , it lacks the species-specific vocal and palate-marking mimicry that is such a striking and interesting feature of other viduid–estrildid coevolutionary relationships (Payne 1985). It is absent from Pintailed Whydah some arid areas where Common Waxbills are common, for Koningrooibekkie instance along the northern Namib Coast and in Namaqualand in the Cape Province. Vidua macroura Historical distribution and conservation: The present range is not known to differ greatly from the past. It seems The Pintailed Whydah is the most ubiquitous and well-known likely, however, that the Pintailed Whydah has colonized viduid finch, distributed widely over sub-Saharan Africa in a many new towns and other human settlements, especially in variety of open habitats. It frequents open mesic habitats of the arid west, in the past 50–100 years. This presumed expan- almost any description, especially mid- and high-altitude sion may have followed habitat alteration, including irrigated grasslands (Tarboton et al. 1987b). Two subspecies are recog- crop production and creation of gardens, parks and dams, con- nized in the region (Clancey 1980b); these appear to have struction of sewage works, and the colonization of these areas continuous ranges. by the Common Waxbill. No threats are apparent, as its habi- Nonbreeding densities are difficult to estimate because it tat requirements are broad. forms seasonally nomadic flocks in most areas. At a study site P. Barnard in the Transvaal (2428DB), call-sites of breeding males in optimal habitat along dirt roads in open Acacia savanna and floodplain were as close as 200 m (mean = 540 m, SD = 420 m) Recorded in 1786 grid cells, 39.4% (Barnard 1989); overall densities in broadly suitable habitat Total number of records: 32 907 were 1 site/12.4–15.5 km2. In the moist coastal strip of the Mean reporting rate for range: 26.6% southern Cape Province (3322DC,DD, 3422BA,BB), adja- cent call-sites were 330–3900 m apart, with overall densities in suitable habitat of 1 site/20.2–23.8 km2 (Barnard 1989). By contrast, in Windhoek (2217CA), an arid area probably colon- ized in the last 50 years, densities are much less. Density is strongly influenced by human settlement patterns, especially Reporting rates for vegetation types where water and grass are in short supply. Call-sites are % 02550 held by a breeding male, with females and nonbreeding males visiting different sites, so overall population estimates cannot E Zimbabwe Highlands 40.9 be made without extensive mark–recapture efforts. Call-site Sour Grasslands 33.2 densities also underestimate the density of males, as there tend Mixed Grasslands 32.9 to be several nonterritorial floaters for each call-site holder East Coast Littoral 32.9 (Barnard 1989). Miombo 31.8 Breeding males are unmistakable, but inexperienced ob- Moist Woodland 30.8 servers easily confuse females and nonbreeding males with Valley Bushveld 25.9 other sparrow-like seedeaters, or overlook them altogether. Alpine Grasslands 23.9 Habitat: The vegetation analysis shows it to inhabit a wide Arid Woodland 20.3 range of open mesic habitats. It occurs in gardens, orchards, Fynbos 19.6 crop- and grazing lands, floodplains, sewage works, roadsides, Sweet Grasslands 19.3 and edge habitats. In arid areas it becomes more specifically Grassy Karoo 16.3 associated with wetlands, as illustrated by the linear distrib- Okavango 14.4 ution along the Orange River. Nama Karoo 10.6 Movements: Reporting rates decreased dramatically dur- Mopane 6.8 ing winter (May–September), but this is largely an artefact of Central Kalahari 6.5 much reduced conspicuousness when males lack breeding tail Succulent Karoo 5.9 ornaments and pied plumage. However, whydahs in most Northern Kalahari 3.1 areas are seasonally nomadic, except where artificial water- Namibian Escarpment 0.7 points and gardens allow individuals to overwinter. Popu- Southern Kalahari 0.6 Viduidae: whydahs and widowfinches 637

14û

PINTAILED WHYDAH 5 1 18û

22û 2 6

26û

3 7 30û Reporting rate (%) > 28.5 13.3 — 28.5 2.0 — 13.2

< 2.0 34û 4 8 18û 22û 26û 14û 30û 10û 34û

60 60 40 1 5 40 20 20

60 60 40 2 6 40 20 20

60 60 40 3 7 40 20 20

60 60 Occurrence reporting rate (%) Breeding reporting rate (%) 40 4 8 40 20 20

J ASONDJ FMAMJ J ASONDJ FMAMJ Models of seasonality for Zones. Number of records (top to bottom, left to right): Occurrence: 91, 13, 150, 861, 1770, 2181, 5612, 940; Breeding: 0, 0, 3, 32, 18, 22, 72, 18.