It’s that time of year again! Time for another Cocky Notes article.
The folks over at Birdlife Western Australia recently asked me to write a short article to contribute to the Summer 2019/20 edition of Cocky Notes. Cocky Notes is a bi-yearly newsletter filled with all things cockatoo in south-western Western Australia. As all three species of Black-cockatoo in WA are threatened Birdlife has several ongoing projects focusing on helping the cockies, and the newsletter is a way to update everyone on their progress. There are also researchers like myself working on the Black-cockatoos and we sometimes contribute to the newsletter to provide updates about our research.
This edition of Cocky Notes has many interesting articles, including information about the new RevegGnangara campaign, breeding season surveys, Operation Rainbow Roost, the new October Red-tailed Black-cockatoo roost count, Major Mitchell’s Cockatoo breeding events at the Eyre Bird Observatory, and an update on Murdoch Uni’s cockatoo tracking project.
You can download the Summer 2019/20 edition of Cocky Notes here. I’ll add my article below in case you are unable to download the full issue right now. You can find past issues here.
Two Forest Red-tailed Black-cockatoos feed in a cape lilac tree in urban Perth.
Return of the Karak
You might have noticed that winter in Perth is a lot quieter these past couple of years, largely due to the lack of Karak (Red-tailed Black-cockatoos) in the city. Once restricted to the Jarrah forest, since 2000 the Karak has been a common sight in Perth, with many people hosting these special visitors in their neighbourhoods as they feed in gardens and street trees. A few years ago, they were urban dwellers year-round, but now the Karak is a summer visitor, visiting Perth between November and May (approx.).
The presence of Karak in urban areas is closely tied to the availability of their favourite urban food, cape lilac seeds, which they extract from the berries with ease. Cape lilac is an exotic street tree that was planted extensively in Perth in the last century. Cape lilac is an interesting tree, the berries stay on the tree for most of the year, as the berries ripen from green (unripe), to white (ripe), to gold (overripe). Overripe berries usually fall from the tree in spring, when the tree develops flowers. Karak will eat the seeds from berries at all ripeness stages, which means that cape lilac can provide food for the Karak for most of the year. Assuming that there are berries on the trees…
The Great Cocky Count shows us that Karak numbers in Perth have drastically increased in the past few years, from 771 in 2016 to 3499 in 2019. This population increase has changed the availability of cape lilac over the year, which in turn has altered the presence of Karak in the city throughout the year.
Prior to 2017, the Karak would stay in Perth year-round, as there were enough trees and berries to support the small urban Karak population. With more Karak feeding on cape lilac in the summer, the food supply doesn’t last as long, and the berries are eaten by winter. Some Karak seem to stay for a while, switching to different foods like Liquidambar and Tipuana, however they too move on eventually, as these foods are only available for short periods. The Karak likely return to the Jarrah forest, where marri and jarrah seeds are usually available somewhere. But come the end of spring, when a new batch of cape lilac berries are developing, the Karak return to the city once more, to fill the skies with their calls, and the ground with the debris from their feeding.
For more information about the urban Karak you can follow me on Twitter @_erikaroper on Facebook facebook.com/UrbanCockatoos, or at my blog erikaroper.com.