Siegfried W.R., Burger A.E. & Frost P.G.H. (1976) Energy requirements for breeding in the Maccoa duck. ARDEA 64 (3-4): 171-191

The Maccoa Duck Oxyura maccoa is a small diving bird which obtains its food by straining invertebrates, mainly Tendipedidae larvae and pupae, from the soft, muddy ooze overlying the bottoms of ponds. The species tends to breed late in the year, when ambient temperatures are relatively high, in the south-western Cape, South Africa. The female produces large eggs, resulting in precocial ducklings. The ducklings obtain their food by diving, soon after hatching. Gonad development in the female was estimated to cost 244 kcal. The egg, weighing 88 g, costs 278 kcal to produce, much more, in relation to the producer's metabolic rate, than any other anatid egg studied to date. Incubation of six eggs required 35.17 kcal per day, increasing the female's metabolic rate. Each embryo contributes a maximum of 48 kcal to the cost of incubation, mostly during the last few days of incubation. The ducklings have large energy reserves at hatching. The time spent by the female on incubation and brood care is made up largely of time spent resting by non-breeding females. The time spent by breeding males on territorial defence and courtship is achieved mainly. through decrease of time ,allocated to resting by non-breeding males, Breeding birds apparently spend more energy than they gain by feeding, and the problem of maintaining a positive' energy balance while breeding is overcome largely through the parents' capacity to store large energy reserves in the form of subcutaneous and visceral deposits of fat. Ambient temperature, rather than availability of food, acting through incubation, may be crucial in controlling onset of breeding and the breeding range of all the small members of the genus Oxyura. For the female Maccoa Duck, maximum daily energy output occurs during egg production, and the female may not always be able to mobilize sufficient energy for successful incubation. Facultative Intraspecific and interspecific nest parasitism occurs in Maccoa Ducks, saving certain females the energy cost of incubation and brood care. This may represent a phase in the evolution of obligate parasitism.