Fluctuations in numbers of Grey Fantails in the Hunter Region of New South Wales

Abstract

Surveys in woodland at Green Wattle Creek (GWC) near Paterson, in the Hunter Region of New South Wales, over 165 consecutive months between 1996 and 2009 have provided a comprehensive understanding of annual and seasonal variation in the abundance of Grey Fantails Rhipidura albiscapa. A period of increasing abundance between 1996 and 2002 was followed by a decline between 2003 and 2009. These trends are attributed to a combination of variation in rainfall and the impact of removal of cattle. The monthly variation in abundance of Grey Fantails involved: (a) stable numbers during the breeding season between October and December, when Grey Fantails were well dispersed; (b) low numbers in January–February, probably as a result of poor survey conditions; (c) low numbers in winter (June–July), typically ~70% of breeding-season numbers; and (d) a pronounced peak in abundance in September and a less pronounced, but more protracted, peak between March and May, which are attributed to migration. In June 2006, numbers of Grey Fantails were exceptionally low, apparently as a result of the prolonged drought conditions prevalent at that time, involving a particularly dry first six months of the year. However, in similar surveys conducted quarterly at a farm adjacent to GWC, where most of the remnant vegetation occurred at the edges of creeks, the decline was minor. It is suggested that under drought conditions resident Fantails leave drier woodland areas in the Hunter Region during winter. However, the trends can also be explained by the adverse impact of drought in south-eastern Australia on Fantails breeding in that area and wintering in the Hunter Region. Counting birds during surveys was shown to have advantages over an analysis limited to the use of presence–absence data.