In collaboration with the Difficult Bird Research Group, we trialled reducing the entry hole into nest boxes last season in attempts to find a more successful option for the threatened Forty-spotted pardalote (FSPAR).
The main competitors for the nest boxes are Striated pardalote (STPAR), Tree martins and Bumblebees.
Striated pardalote in particular has been increasing their takeover of existing FSPAR nests over the years, happily breaking FSPAR eggs and laying their own.
Fifty-four boxes were monitored at the Inala Private Nature Reserve in the 2023 breeding season.
The first phase of this experiment installed faceplates with three diameter sizes for the entry hole: 23, 24 and 25mm. It quickly became apparent that none of the birds could get in the 23mm hole.
The 24mm hole proved good for FSPAR with nine pairs successfully raising their chicks, but although tight for STPAR, 14 pairs of this competitor succeeded in raising chicks.
However, no existing FSPAR nest were taken over by their cousins.
For the 25mm hole, only three FSPAR fledged chicks, whereas 19 STPAR raised theirs. They also usurped quite a few boxes where 40spots had already established a nest.
Thus we’ve concluded that 24mm faceplates should be installed on boxes to help 40spots raise more chicks, and reduce the prevalence of the Striated pardalote and other species.
We also intend to trial other options in coming years.
