Use of legs as dissipators of heat in flying passerines

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Nest-site selection in the Cape Sugarbird

Cape sugarbirds, Promerops cafer, preferred certain pro tea bushes as nest-sites. These bushes were characterized by relatively large leaves and dense foliage. Nests were usually placed in the central parts of bushes Nest-sites were shielded from the cold night sky, and were associated with relatively favourable air temperatures and protection from wind in a season of unfavourable weather. Data on microclimate of nest-sites, together with those on heat loss from an incubating sugarbird, were interpreted in relation to nest-site selection as adaptive behaviour promoting breeding success through conservation of energy. Sugarbirds nesting relatively high off the ground and in dense vegetation were considered to be decreasing die risk of exposure to predators

Social behaviour of Jackass penguins at sea

This paper reports flocking, communal feeding and other aspects of sea-based social behaviour in the jackass penguin (Spheniscus demersus). Penguins tend to occur within about 15 km of the mainland, but range farther afield from the islands used for breeding and/or roosting. Relatively large groups of 50 and more birds occur more than 50 km from the nearest island, but seldom more than 15 km from the mainland. The majority of the sea-going population consists of birds occurring in groups. Mean group size is eight birds. In any one particular group the members all tend to perform the same behaviour at the same time. The tendency to form foraging groups and the highly synchronized diving and cohesion of these groups indicate that this behaviour is socially facilitated, suggesting that it is adaptive in terms of both enhanced prey location and capture. Feeding penguins do not submerge for long and do not dive deeply. Birds in diving groups perform head-dipping movements which might signal readiness to dive and thus promote synchronous activity. The paper points out how little is known about jackass penguins at sea - the environment in which they probably spend the majority of their time. Lack of information on the birds at sea precludes proper interpretation of many land-based events attending the biology of the bird and its conservation

Activity budgets of male Maccoa ducks

The behaviour of breeding and non-breeding male maccoa ducks (Oxywa maccoa) was studied in South Africa. Individual ducks were observed continuously from sunrise to sunset in the wild, and all ritualized and non-ritualized behaviour was recorded. Diurnal time budgets of territorial and non-territorial males were translated into energy budgets, showing relative time and energy expenditures for resting, foraging, preening and bathing, territorial defence and courtship activities. A territorial male spent one-third of the daytime on active behaviour associated with reproduction. Territorial males averaged 297 displays per fifteen-hour day, or about one display every three minutes. Active defence of territory occupied 15 per cent of a male's time budget, adding an estimated 20 per cent to the energy a non-breeding male spent on self-maintenance. Active courtship of females occupied IS per cent of a male's time budget, adding 18 per cent to the energy a non-breeding male spent on self-maintenance. The increase in time spent on reproductive behaviour over that of a non-breeding male is achieved mainly through decrease of time allocated to resting in the budget of the non-breeder. Territorial males increased energy expenditure by a factor of 1,3, but devoted the same portion of time as non-breeders to actual feeding (21 per cent). Energy and time-saving strategies were associated with territorial defence and courtship, contributing towards optimization of time and energy budgeting

Plumage and ecology of cormorants

The paper draws on data attending the etho-ecology of four species of cormorants (Phalacrocoracidae) in support of an hypothesis for the adaptive significance of the predominantly dark plumage of these birds. It is suggested that a dark plumage, primarily by being most receptive to solar radiation, assists cormorants in supplementing metabolic heat for maintenance of normal body temperature. In those cormorants which have white extending over ventral and frontal aspects of the body, it is suggested that this is an adaptation to the feeding situation and that it promotes 'hunting camouflage' through countershading

Avian pollinators and the pollination syndromes of selected Mountain Fynbos plants

The flowering phenology of Erica and proteaceous plants and the abundance of nectarivorous birds were monitored in Mountain Fynbos in the Jonkershoek State Forest, South Africa. Species tended to flower for short periods in summer at high altitudes, or for longer periods in autumn and winter at low altitudes. Three avian species apparently tracked the flowers occurring at low altitudes during winter and, when present, at high altitudes during summer. Statistical analyses confirmed that the distribution of Promerops cafer is primarily correlated with the abundance of protea flowers, and that of Nectarinia violacea with Erica flowers. The evolution of an unusually high ratio of putative avian pollinators to ornithophilous plant species in Mountain Fynbos is discussed

An analysis of faecal pellets of the brown hyaena on the Namib coast

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