Purple-crowned fairywrens are more flexible in their breeding behaviour than we thought, which has helped the bird population to grow in one wildlife sanctuary in Western Australia
5 January 2022
For the second year in a row, researchers have spotted purple-crowned fairywrens – small birds that dwell near creeks and rivers in northern Australia – reproducing outside their usual breeding season. The findings indicate that the reproductive behaviour of the birds is more flexible than we had previously thought.
Purple-crowned fairywrens (Malurus coronatus) are light-brown birds with pale bellies and long blue tails. Breeding males can be identified by their vibrant purple crown and black cheek patches. Females have grey heads and reddish-brown cheek patches.
The birds typically breed during the Australian wet season, between December and April. However, Niki Teunissen at Monash University in Melbourne and her colleagues have found that dry season breeding has become more widespread among the western subspecies of the bird (M. coronatus coronatus) in recent years.
During their 2020 and 2021 surveys of the birds at Mornington Wildlife Sanctuary in the Kimberley region of Western Australia, they found extensive evidence of fairywren reproduction throughout the dry months, from May to November.
“I found that over half of the groups had young fledglings at the end of the dry season, which means that they had bred successfully during the dry season,” says Teunissen. “In addition, nearly half of the dominant females that I caught had a brood patch – a bare patch on the belly that they use to keep eggs warm – which is evidence of them having an active nest.”
The extended breeding period has resulted in a substantial rise in the fairywren’s population at the sanctuary, from 143 individuals in November 2020 to 204 in November 2021.
“Considering the substantial population decline we observed between 2018 and 2020 due to drought and fire, it is very positive to see the population numbers climbing back up as a result of their active breeding,” says Teunissen.
The above-average rainfall of the 2021 wet seasons may have contributed to the shifts in breeding patterns, as water levels will have remained relatively high into the dry season. But this doesn’t explain the dry season breeding of 2020, says Teunissen.
She says it’s “hard to say for sure” what is driving the dry season breeding, but “hopefully, this flexibility in timing of breeding allows the fairywrens to breed successfully during the dry season if they have been unsuccessful during the previous wet [season]”.
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