Abstract
f Editors Note: The following data have been extracted from a paper published in The Ostrich, an organ of the South African Ornithological Society. The paper was written by David M. Skead in 1974./
The Estrildinae are a group of small to very small seed-eating birds found in Africa, Asia, and Australia. Delacour ( 1943) recognized J 08 species in l S genera ... Hall and Moreau (1970) place them in a separate family, the Estrildidae , and recognize 67 species for Africa.
This group is well known to aviculturists throughout the world, but apart from many studies under aviary conditions it has received scant attention from field ornithologists in Africa.
HABITAT
The Yioleteared Waxbill (Uraeginrhus granatinus} was chosen for special study. The main study area was in the bushveld just north of Pretoria, South Africa. All four species [the study included the Blackcheeked Waxbill, the Melba Finch, and the Blue WaxbiJl] are chiefly birds of dry Acacia thornveld which is evident from a search through the literature for southern Africa and from personal experience.
Being birds chiefly of the Acacia thornveld found in drier areas is, to use a loose South African agricultural term, "sweet" veld as opposed to the "sour" veld of the higher rainfall areas. A further advantage is that the scrub areas support a good grass cover from which they achieve their main source of food in the form of grass seeds; and, if the bush is low and dense then cattle and antelope cannot get their heads in to graze the grass before it seeds. This is also an advantage when it comes to building nests with green inflorescences.
SOCIAL ORGANIZATION
Viole teared Waxbills are occasionally found in small parties but generally they move about as singletons or in pairs. Pair formation takes place when birds are still sub-adults and the pair bond is strong and maintained for life. Only one party of ten Violeteared Waxbills was seen during the study period.
FOOD
All four species may be found feeding and dri.nking together although some interspecific fighting does occur - Interspecific fighting would appear to take place only where food supplies or water sources are limited.
Food has been the least studied aspect of the ecology of the species and apart from lmmelmann and lmmelmann ( 1967) nothing has been recorded about their diet in the wild except such loose statements as grass-seeds and insects.
All four are primarily seed-eating with insects, especially termites, being taken in varying degrees. The diet of the Melba Finches was almost impossible to obtain from direct observation because being a ground-feeding species they simply disappear from sight in the grass cover. Violeteared Waxbills which readily perch on grass inflorescences to feed on the seed are easily observed, but this behavior is of limited duration and for much of the year they must resort to ground feeding .. Jt is probably true that most small grass seeds will be eaten, the limiting factor being the size of the seed.
DRINKING
Drinking behavior of the birds has received attention in recent years from a number of workers in the arid parts of Southern Africa .No work had been done in a less arid climate until trapping began at a water point in this study.
Figure 2 shows the percentage monthly trapping of the .. species studied in relation to monthly percentage of rainfall. The dry-season peak .. June to September, is immediately clear. This is to be expected in birds subsisting largely on a diet of dry seeds. During the rainy season they can obtain enough water from green grass-seeds, invertebrates, or other green plant food. Furthermore, although no records exist, they can surely obtain enough water from early morning dew. They frequently visit roadside pools and dams that fill with summer rains.