Richard Segal – PhD student, Charles Sturt University, The Lord Howe Island Signal

The Lord Howe currawong is one of the most recognisable and commonly encountered native bird species on Lord Howe Island. They are often curious about people and always keen for a sultana or two. Until recently, little was known about the currawong, including where they prefer to nest and how many of them are breeding. For example, do all birds nest each year or only some of them? Do they nest across the island, or do they favour certain areas?

I recently completed a study to answer these questions using nesting data collected during the 2017 and 2018 breeding seasons. Searching the island’s forested areas was a time-consuming and sometimes exhausting process, but my supervisor (Associate Professor Melanie Massaro) and I (with the help of many others – thanks!) located 73 nests. I combined the nests’ locations with topographical and vegetation maps in a computer software program to identify their preferred habitat and produce colour-coded maps to calculate how much of these habitats exist on the island.

My study found that currawongs prefer to nest in the forested gullies and creek lines across the island. Currawongs may like these areas as the damp conditions are likely to provide a reliable food supply for their chicks during the breeding season (e.g. spiders, worms and lizards). Several nests were found in the northern hills and Transit Hill, but we found the most nests in the Soldier Creek, Rocky Run and Boat Harbour areas. The currawongs showed no preference for a particular type of forest or a tree species to nest in. From my maps, I calculated that currawong breeding territories were around 5 hectares each and that currawongs used only around one-third of the island’s area to breed each year. Because currawongs don’t use the whole island for breeding, I found a limit on the number of currawongs that can breed each year on the island. I calculated that only 84 pairs of currawongs can breed at one time on the island. The total number of currawongs is estimated to be 240 birds. So that means that at least 70 currawongs (30% of the total population) aren’t breeding.

My findings that there is limited breeding habitat are important for the ongoing conservation of the Lord Howe currawong. Unless conditions on the island change (from a currawong’s point of view), the currawong population can’t grow any larger than it already is because of the limited suitable habitat in which to breed. For example, if food resources were to increase in the future, breeding territories could be smaller, allowing more currawongs to breed. Alternatively, more of the island could become suitable for nesting. As a result, the currawong population could increase, making the currawong more likely to survive on the island into the future.

I would like to thank all of you, who allowed me and my supervisor Melanie to check currawong nests in your garden. Thanks to Leon for many cups of tea and biscuits and never-ending stories about currawongs. Thanks to Fitzy for allowing us to search his property for nests. Finally, I would like to thank Hank and other Lord Howe Island Board staff for their support. I have collected more data on currawong breeding success and their diet from my time on Lord Howe Island and I look forward to sharing these results with you in the future.

This article appeared in The Lord Howe Island Signal, 28 August 2021.