Bird researchers returned to the Kimberley last month, for the first time since the region was hit by devastating flooding in January, and were relieved to find that the majority of the endangered western Purple-crowned Fairy-wrens (Malurus coronatus coronatus) survived and were still breeding.
Australian Wildlife Conservancy's (AWC) Mornington-Marion Downs Wildlife Sanctuary (on Bunuba and Kija Country), and its neighbours in the central Kimberley entered a state of emergency in January, when ex-Tropical Cyclone Ellie inundated the region with record flooding. AWC staff and visiting researchers, including those working with the Purple-crowned Fairy-wren, were evacuated by helicopter. In the months after, AWC's Kimberley team returned to the sanctuary to conduct damage assessments and commence restoration work. The team repaired road access and restored electricity and water facilities which has enabled more staff and researchers to slowly return and resume important conservation activities.
Ariana La Porte Monash University PhD students Ariana La Porte and Ian Hoppe briefly returned to Mornington Wildlife Sanctuary in May, to resume an 18-year study on the fairy-wren population led by Professor Anne Peters. This was their first trip back since being evacuated due to flooding in early 2023. The researchers hoped to assess the impact of the flood on the fairy-wrens' survival via a population census and gauge breeding success following the recent wet season.
Much to the researchers' relief, the Purple-crowned Fairy-wrens proved to be resilient, with most birds having survived the floods. The population was estimated to be at 242 in May 2023, a slight decline compared to 256 birds in November 2022 (one month pre-flooding).
Ariana La Porte "Although the fairywrens have taken a bit of a hit from the flood, they are doing well considering," said Ian. "About three quarters (74%) of the adult birds that were present in a census of the population at the end of 2022, just before the floods, are still alive now. This survival rate is lower than we usually observe over the November to May time period, however it is not as devastating as we might have expected from such an extreme flood event."
In the 2020 Action Plan for Australian Birds, the impact of increased flood frequency was identified as a medium-level threat for this species, which warranted further research as a high priority. Across its range, the Purple-crowned Fairy-wren is also threatened by habitat degradation by over-grazing and inappropriate fire regimes.
Ariana La Porte Researchers were also thrilled to discover that 24 out of the 67 breeding groups in the population had fledglings, young free-flying birds that were being fed by the adults. This was a relief given that all active nests had been washed away in the January flood. Multiple groups were also found to be breeding in May, one month later than the end of the usual breeding season (December to April). These individuals were found feeding young chicks in the nest, incubating eggs and even starting to build new nests.
"Although surprising to see that the birds are still breeding this late in the season, we're not entirely shocked," Dr Niki Teunissen Associate Researcher explained. "We have noticed that in wet years birds often keep breeding for longer. Presumably this is partly because in very wet years, floods frequently wash away nests, and birds don't breed successfully until later in the season."
Brad Leue/AWC Overall, researchers were impressed by the fairy-wren's ability to survive the extreme weather event.
"We are confident that the population will bounce back," Dr Teunissen added.
