Seasonal Fluctuation of Waders in Gulf St Vincent, 1976-85

Abstract

The numbers and seasonal fluctuation of waders (Sub-order Charadrii) in Gulf St Vincent, South Australia, were assessed by different methods of counting in the years 1976-85. Forty-three species were recorded, nine of them too rarely to allow comment on seasonality.

The majority of species of palearctic migrant increased for most of the period between August and February, and several mcreased markedly in November-December. Several species showed a greater tendency than in eastern Australia to increase in late summer (ca February). Most species reached their peak around February and then decreased rapidly. Immatures of six species increased thereafter. Twelve species were relatively numerous in some austral winters.

Native wetland species showed diverse trends, although most peaked in December-March, including the Black- winged Stilt, which showed only slight seasonal variation, and the Masked Lapwing, which remained relatively numerous until June. The Black-fronted Plover increased in winter. The effect was discussed of flooding in the Eyrean drainage in 1984. Indications were found that some species were influenced by the climatic patterns of the arid interior of the continent as well as of the wetter south.