Waterbird abundance in eastern Australia, 1983 - 92
In: Wildlife research, Band 26, Heft 3, S. 351
ISSN: 1448-5494, 1035-3712
We examined the relationships between abundance of 16 species of waterbirds
and the rainfall in eastern Australia, the rainfall west of this region, the
annual Southern Oscillation index (SOI), the wetland area, and hunting in
eastern Australia for the period 1983–92. Data were collected during
aerial surveys of eastern Australia. For most explanatory variables, lags of
up to five years before aerial surveys were also investigated during these
analyses. The analyses covered all nine game species (plumed whistling-duck,
Australian shelduck, Australian wood duck, pink-eared duck, grey teal,
chestnut teal, Pacific black duck, Australasian shoveler, hardhead) and seven
non-game species (Australian pelican, white-faced heron, yellow-billed
spoonbill, freckled duck, black swan, black-winged stilt, red-necked avocet).
Regression models were developed for all species apart from Australian
pelicans. Rainfall and climate indices generally were most correlated with the
species' abundance. Bonferroni adjustments to significance levels meant
that there were significant variables in regression models for seven of the 16
species. Abundance indices for plumed whistling-duck, chestnut teal, hardhead,
black swan and black-winged stilt were related to the climate variables
(rainfall, SOI) and wetland area, whereas abundance of pink-eared duck and
red-necked avocets were negatively related. Abundance of chestnut teal was
positively related to numbers of hunting licences sold. The results are
equivocal about the role of hunting in determining waterfowl abundance, which
is probably a reflection of few data points and numbers of variables included.
In general, abundance indices of waterbirds appear to have decreased between
1983 and 1992, which may correspond to other factors not modelled