Studies of waterfowl productivity at the Pukepuke Lagoon Wildlife Management Reserve have shown high mortality amongst young ducklings. This has been found in other studies in which it has often been attributed to predation. (Evans and Wolfe 1967, Balser et al. 1968, Urban 1970, Schranck 1972). Areas of pasture, cut-over pine forest, and dunes outside the reserve were also included in the trapping area.
This is a preliminary account of some basic waterfowl population studies being undertaken at Pukepuke Lagoon, the first such studies so far attempted in New Zealand. Attention has been focussed on the popular game species of duck; the introduced mallard (Anas platyrhynchos platyrhynchos), the native grey duck (Anas superciliosa superciliosa) and New Zealand shoveler (Anas rhynchotis variegata). Seasonal fluctuations in population density, sex-ratios, nesting season chronolgy and the influence of water levels on hatching success are discussed
Numerical and spatial components of dispersion, and the activity of pukeko (Porphyrio p. melanotus) in swamp and pasture in coastal Manawatu, New Zealand, are described. Pukeko are concentrated in few locations during the autumn population peak, but are widely scattered in spring when the population size is minimum. Flocks are consistently larger in pasture than swamp; those of up to ten birds are more frequent in swamp. And those of 25 or more birds more frequent in pasture. In pasture, pukeko distribution and density declines outwards from the edge nearest to water.