TWBBI update November 2024

Nest boxes for forty-spotted pardalotes

Manufacture and installation of forty-spotted pardalote (FSPAR) nest boxes was postponed due the increasing observations of FSPAR being excluded and even displaced after commencement of nesting in nest boxes by two competitors – Striated pardalotes (STPAR) and Fairy martins (FM). This was first recorded by Edworthy (2016) but has since been observed in increasing frequency across the range, with Hingston (pers comm 2023) seeing successful fledging at Inala plummet 80% between the 2021 and 2022 breeding seasons. Increasing the populations of competitors is seen as a threat to the FSPAR population.
Thus , in collaboration with the Difficult Bird Research Group (ANU), we commenced a trial to test the hypothesis that competitors could be excluded by using smaller entrance hole sizes.
Fifty-four nest boxes have been monitored at Inala through this breeding season, with 51 of these having entrance hole sizes smaller than used previously. It has been found that 24 mm diameter is the minimum entrance hole size that forty-spotted pardalotes can use, and that both 24 mm and 25 mm diameters are effective at excluding tree martins from boxes. Although striated pardalotes have been recorded entering boxes with 24 mm or 25 mm holes, this appears sufficiently difficult that these smaller holes provide some protection of forty-spotted pardalote nests from usurpation by striated pardalotes. However, the risk of smaller holes being blocked remains a concern. Summaries of forty-spotted pardalote nests and empty boxes are attached. This research is ongoing, and possible other alternative nest box designs may need to be trialed next year.

Revegetation completed 2023

Approximately 7 ha across 6 properties has been planted to provide foraging habitat for swift parrots and forty-spotted pardalotes. These plantings comprise 496 Eucalyptus viminalis and 12 Acacia melanoxylon for forty-spotted pardalotes, and 221 Eucalyptus globulus and 77 E. ovata for swift parrots.
Originally we intended close spaced plantings (5x5m grid) but have decided to use a 10m grid as the intent is large crowns to promote flowers for foraging for the two bird species. We include understorey as well where it is absent.

Preparation for 2024

Planning is well underway for provenance trials designed by University of Tasmania for Eucalyptus viminalis and E. globulus. Both trials will be planted in winter 2024. Seed of 8 provenances of Eucalyptus viminalis has been sourced from UTAS and one revegetation provenance from Bruny that has seedlings establishing in the wild, for planting in 2024. The seedlings will be grown at Woodlea Nursery. Ten replicates each will be planted in the north and the south of Bruny Island.
For E. globulus, 17 provenances have been identified for planting, including two precocious provenances. Plans are also developing to include two other precocious-flowering eucalypts (Eucalyptus leucoxylon and Corymbia ficifolia) within this trial to test options for providing rapid increases in food availability for swift parrots. Most of the seed for this trial has been sourced, and STT have agreed to propagate this at their nursery. Both trials will be planted across multiple locations, the selection of which is well underway.
For both of the provenance trails, we have been working with Dr Peter Harrison and Professor Brad Potts of UTAS, using their expertise in genetics, likely future climates, trial design and analysis. Both they and Dr Lachie Clark from Sustainable Timber Tasmania (STT) are also giving material support.
Sustainable Timber Tasmania (STT) have agreed to supply us with seedlings of E. globulus and E. ovata, which they can grow at their nursery for both the provenance trial and general planting. They are currently checking availability in their seed stores of 15 provenances of E. globulus and 3 provenances of E. ovata that have been identified as suitable for predicted future climates on Bruny Island. In addition, we have procured seed of two dwarf precocious-flowering provenances of E. globulus and two other precocious-flowering species of eucalypts (Eucalyptus leucoxylon and Corymbia ficifolia). This seed will be sown and grown at STT’s nursery.