Brood care, pair bonds and plumage in southern African Anatini W . R O Y SIEGFRIED In the Holarctic, migrant species of sexually observations cover 43 5 broods recorded over dimorphic Anatini have a bond between male the last 15 years. The records derive from all and female breeders that is seasonal only and parts of southern Africa, taken here as the breaks soon after egg-laying. The male entire sub-continent south of about 15°S. usually deserts his mate and joins other The brood records were analysed accord­ males while undergoing the post-breeding ing to number and age of ducklings, the moult. Reports of males of North American presence of one or two accompanying adults, ducks accompanying their females with and in relation to place and time of breeding broods are regarded as rare exceptions (Table 1). Presumably some of the records (Oring, 1964). of two adults in attendance could apply to According to Kear (1970), pair bonds are two females and not necessarily male and of relatively long duration in certain species female, since in five of the six species only an of sexually monomorphic Anatini, and prob­ expert can tell the sexes apart in the field. ably also in a number of near-tropical ones. However, my own records indicate that the Weller (1968) noted that those Argentinian incidence of two females accompanying the species which retain a long pair bond are same brood is rare, and that it is quite in those in which males commonly attend the order to regard the two attending adults as broods. A related general comment is that male and female parents. males of monomorphic southern hemisphere anatines regularly accompany their females with broods. However, there is no published Brood care account providing quantitative, comparative data on this phenomenon. It is clear from Table 1 that in the Cape Teal This paper summarizes unpublished re­ both parents almost invariably accompany cords and appraises the significance of males their young, and that the male normally accompanying females with their broods in remains with the female and the ducklings six species of southern African Anatini, viz, until they reach flying age. How much longer African Black Duck Anas sparsa, Cape Teal the pair and parent-young bonds may persist A. capensis, African Yellowbill A. undulata, is not known. Red-billed Teal A. erythrorhyncha, H otten­ The African Black Duck is the only other to t Teal A. punctata and Cape Shoveler A. species, of the five remaining here, in which smithii. F or these species, there are 360 brood males have been observed accompanying records on file with the African Wildfowl females with well-grown young. However, Enquiry. In addition to these data, my own the evidence for this is ambiguous, due to the Table 1. Incidence of male and female parents accompanying broods. Figures in parentheses represent numbers of broods accompanied by both parents, other figures refer to broods accompanied by females only No. broods and age (in weeks) of ducklings Total no. Species broods 0-1 1-3 3-5 5-7 observed A. sparsa 11 9 7 6 33 (2) (2) (4) A. capensis 3 4 1 2 10 (40) (28) • (15) (13) (96) A. undulata 98 89 57 40 284 (10) (4) (14) A. erythrorhyncha 18 19 11 7 55 (8) (11) (5) (24) A. punctata 5 5 5 2 17 (1) (1) (2) A. smithii 86 66 46 27 225 (21) (8) (4) (33) 33 34 W. Roy Siegfried species’ secretive habits, its localized and Table 2. Mean brood size in relation to age and ‘difficult’ habitat, and other factors which are parental accompaniment. Figures responsible for a general paucity of observa­ in parentheses represent broods tions and unsatisfactory, incomplete records accompanied by both parents, other (Siegfried, 1968). Current work, involving figures refer to broods accompanied by- individually marked wild birds, indicates that females only. Sample sizes are given in the African Black Duck has a long-standing Table 1 or permanent pair bond. It is probable (Sieg­ Mean brood size in fried, 1968), th at the males tem porarily desert relation to age (in weeks) their mates with young broods, but remain Species inthesame general area (the permanent home 0-1 1-3 range of the pair) and later rejoin the female. There is one record of a Cape Teal male A. ervthrorhyncha 7-16 6-42 moulting wing feathers while accompanying (7-12) (5-10) a female with a brood. There are no observa­ tions of brood-accompanying males directly A. smithii 7-00 5-12 helping to care for the young. There are (6-72) (4-42) isolated records of brood-accompanying males driving off conspecific males in the Red-billed Teal and the Cape Shoveler, but male’s attendance has operated mainly for this behaviour has not been observed in the reasons other than increased survival and African Yellowbill and Hottentot Teal. In success of the brood per se. Broods hatched the Cape Teal brood-accompanying males early in the season were no more often frequently drive away other males. How­ attended by males than late-hatched ones, ever, the male’s aggressiveness is usually but this conclusion is based on inadequate associated with Inciting by the brood female data. The data were insufficient to compare and thus appears to be an expression of the incidence of male attendance in different sexual behaviour rather than defence of the geographical areas of breeding. Such com­ young. Such parental behaviour as brooding, parisons, particularly in the Red-billed Teal, distraction display, active defence of young might contribute much towards understand­ and leading them to safety are performed ing how and why the male’s behaviour varies. solely by the female. Thus, males which accompany females with broods apparently do so as an extension of the pair bond Ecological synopsis through the attraction provided by the female, and the presence of the brood itself Before exploring whether relationships be­ exerts no extra inducement. Of course the tween parent and young can be correlated male’s attendance could still promote sur­ with morphological and behavioural char­ vival of the young through enhanced pre­ acters of the various species, it is necessary dator detection. to report certain ecological features of funda­ The Cape Shoveler, Hottentot Teal and mental importance as selective pressures African Yellowbill males do not regularly shaping the species. Synoptical accounts are accompany their mates with broods. The set out below, based on personal observa­ Red-billed Teal occupies a position inter­ tions supplemented by information taken mediate between these three species and the from the literature. They are substantially Cape Teal. In the African Yellowbill and to correct in outlining the generalized condition a greater extent in the Cape Shoveler it is applicable to each species, and should be evident that some males do continue, for a regarded as no more than that. The accounts limited time, to associate with their mates are compiled from (a) data collected in those while their ducklings are young; the in­ parts of the natural range of a species in cidence of this behaviour appears to be more which it is most num erous, and (b) from frequent in these species than in their North populations which are not, or very little, American counterparts, the Mallard A. affected by man-made changes to the en­ platyrhynchos and Northern Shoveler A. vironment. The main artificial factor, which clypeata (ef. O ring, 1964). has a considerable bearing on the ecology In the Red-billed Teal and Cape Shoveler of southern African waterfowl, is the ever- (the two species with sufficient data for com­ increasing multitude of water storage and parison) the parental male’s presence appears irrigation schemes; these are most developed to be of no advantage to the size of the brood in the Republic of South Africa. However, (Table 2); which tends to bear out the con­ there are still extensive areas of southern tention that in these species selection for the Africa which contain pristine wetlands and Southern African Anatini 35 their populations of waterfowl. The biologist parties, but often encountered in flocks of a cannot evaluate the survival value nor inter­ thousand or more. A regular, annual, sea­ pret properly the evolutionary significance sonal breeder in well-watered areas of regular of an animal’s behavioural (or other) adapta­ rainfall. Social courtship occurs. tions without recourse to a study of the natural condition. Moreover, recently it has become clear that features of social behaviour Hottentot Teal can vary considerably within a species, with different populations showing adaptive Tropical zone. Localized and nowhere modifications most effectively appropriate numerous. Found mainly on permanent to the ecological circumstances under which sheltered waters, but also floodplains in rela­ they live (Crook, 1970; Watts & Stokes, tively well-watered regions. Resident, with 1972). local short-distance movements. Usually in pairs and small parties. A regular, annual, seasonal breeder. Social courtship occurs. African Black Duck Temperate zone. Localized and nowhere numerous. Inhabits perennial rivers and Cape Shoveler streams. Sedentary with a permanent home range. Usually in pairs and never congregates Temperate zone. Locally common and into large groups. A regular, annual, seasonal numerous. Inhabits most typically shallow, breeder. Social courtship reduced. seasonal vleis in areas of dependable rainfall. Suspected migrant with long-distance move­ ments, though part of the population is Cape Teal resident. Usually in pairs and small parties, though often encountered in flocks of a Temperate zone. Locally common. Most hundred or more. A regular, annual, seasonal typically inhabits alkaline waters of short­ breeder. Social courtship occurs. lived nature in arid areas.