The Superb Parrot (Polytelis swainsonii) is a beautiful inland parrot that is considered to be vulnerable to extinction in the wild by both state and federal governments. It is found in two states (New South Wales and Victoria) and the Australian Capital Territory, and despite moves to reduce its threat category is expected to decline in abundance in the future. Canberra is a rapidly growing city, and part of its current expansion is into part of the key habitat of the Superb Parrot around Canberra. As the Superb Parrot is listed as vulnerable federally and in the ACT, this loss needs to be either avoided or offset.
The new suburb of Throsby in Gungahlin originally covered an identified Superb Parrot breeding site, but after the value of the site was recognised much of it was preserved. As part of its offset strategy for Throsby, the ACT government asked Doctor Laura Rayner and Professor Adrian Manning to investigate the status and ecology of this population and another offset area in the Molonglo Valley in the 2015 breeding season, continuing on across the 2016 and potentially 2017 breeding seasons. The report delivered on the 2015 breeding season to the Environment and Planning Directorate can be found at the bottom of this post.
My job on the 17th and 18th of October was to help Laura manage the ropes for climbing the trees, and spot her if necessary. This was done to change the batteries in the cameras monitoring the known Superb Parrot hollows, and check which hollows actually contained an active nest. While there was the potential that the tree-climbing could discourage the Superb Parrot pairs from choosing the investigated hollows, they are thankfully relatively tolerant to intrusion, and we tried to minimise the time spent around active nests. Later, the chicks will also be removed from the nests temporarily for banding. I was also keeping an eye out for where the Superb Parrots were moving- we found several pairs that had moved hollows since Laura’s last visit to Throsby Ridge or were still actively searching for nesting hollows.
The two main competitors for nesting sites at the site were the Common Starling (Sturnus vulgaris) and Crimson Rosella (Platycercus elegans)- there were plenty of other birds nesting, but the Sulphur Crested Cockatoo (Cacactua galerita), for instance, favours a much bigger hole. And while a pair of Superb Parrots will ferociously defend their hollow once established, they are very obliging and will readily abandon preferred hollows to an interested Crimson Rosella before their chicks have hatched. The retention of the group of old nesting trees is highly important, as it appears that Superb Parrots prefer to nest in a group, although not too close together. For such ‘clumping’ nesting behaviour, scattered and isolated remnant old trees like those preserved in other Gungahlin suburbs like Forde are not really enough.
As mentioned, this is the second year of monitoring at Throsby Ridge. Many of the hollows being used this year are the same ones as last year, although it appears that Superb Parrots do not return to the same hollow as they used last year. The Superb Parrots are also later arriving this year- with the exceptionally good conditions inland it is possible that the mainly seed-eating Superb Parrots are enjoying the good times, or are even nesting further inland than usual. However, we do not know enough about their population dynamics to really answer this question. Hopefully, more birds will continue to arrive, as it is not yet too late for them to claim nests. Last year, breeding success was limited by the availability of hollows- some of the less experienced pairs, or those who arrived late were in poor hollows. This year, there are currently fewer birds overall attempting to breed at Throsby Ridge, and there is a surplus of hollows. However, this does not render the old paddock trees any less important; this year is more likely to be an aberration than the normal situation. So any loss of the trees to further development, even for recreational facilities, could have a catastrophic effect on the ability of Superb Parrot pairs to successfully breed at Throsby Ridge. Thankfully, only one known nesting tree was lost in the development of the scaled-down version of Throsby, although it is possible that the nearby earthworks is discouraging birds from nesting at Throsby Ridge this year.
Where to from here? The Superb Parrot, despite its iconic status, is surprisingly enigmatic. The most pressing problem with Superb Parrots is that not enough is known about their migration patterns. Superb Parrots migrate from the northern parts of their range (north-central New South Wales) to the southern parts of their range (Southern tablelands, Slopes and the Riverina) in spring to nest, returning north in autumn. However, there is very little known about the actual nature of this migration. So, the next step in this research is to begin a banding and radio monitoring programme. Ideally, all the Superb Parrots at Throsby Ridge would be banded so that any newcomers could be spotted the next year.
This would tie in very well to an investigation of the greater Superb Parrot metapopulation (a population of populations) in the Australian Capital Territory and the Southern Tablelands. The banding can provide some useful info about the movements of the Throsby Ridge Superb Parrots, but a radio tracking programme would provide far superior results. Unfortunately, the equipment required for this is expensive, and beyond the budget of the current research funded by the ACT government. To try and implement radio tracking at this stage would be an unfortunate example of mission creep, but should be implemented as a future project when funding becomes available. In the meantime, it is vital that the current monitoring at Throsby Ridge continues, with possible expansion to consider adjacent Superb Parrot populations. Superb Parrots are beautiful birds to work with, and I was very thankful to Laura for allowing me to come along help ensure that they have a secure place in Canberra’s urban landscape.
Lachlan Bailey- u5584584
For more reading-
Technical report by Laura Rayner, Dejan Stojanovic, Robert Heinsohn and Adrian Manning to the ACT Government on the Breeding Ecology of the Superb Parrot: