Surprises caught on camera
We observed swift parrot nests using motion-activated camera traps high in trees, and we discovered surprisingly high parrot death rates. The cameras showed that sugar gliders kill and consume the adult bird and her eggs when they visit the swift parrot nests at night.
Despite being widely distributed throughout the Tasmanian mainland, sugar gliders appear to have been introduced there at the beginning of the 20th century. Although sugar gliders are commonly thought of as primarily nectar/insect feeders, our data show that they are also an important but opportunistic bird predator.
Cameras showed that the poor survival rates of swift parrot nests are caused by sugar glider predation. Only a small percentage of 2017% of swift parrot nests on Tasmania’s mainland were successful, and we discovered that while many predators attempted to prey on parrot nests, only sugar gliders were successful. Approximately 80% of the sugar glider predation events led to the adult female parrot’s death in addition to her eggs, and reports of sugar glider predation have been made in all of the regions where swift parrots breed on Tasmania’s mainland.
It’s interesting to note, though, that the pressure from sugar glider predation varies depending on the area of Tasmania where swift parrots breed. For example, sugar gliders are not found in Tasmania E2%80%99’s offshore islands, and island-breeding swift parrots successfully rear 10%20100% of their nests
However, it appears that sugar glider predation might be a sign of a more serious issue. We discovered a relationship between glider predation and forest cover on the Tasmanian mainland, where sugar gliders are present in all swift parrot breeding grounds. Mature forest cover was higher and glider predation was lower in areas with lower levels of logging.
Conversely, in areas where the amount of mature forest cover had decreased due to factors like logging, urban development, wildfires, etc., swift parrot nests experienced rates of predation as high as 10%. These findings suggest that the relationship between swift parrot breeding success and forest loss is more nuanced than previously thought. Given that deforestation is still occurring, immediate research is required to understand the relationships between swift parrots, sugar gliders, and the existence of mature forests (and the tree hollows these forests support).
A difficult bird to study
Swift parrots are difficult to study. Swift parrots migrate from the Australian mainland to Tasmania every spring to breed, but they hardly ever return to the same nesting site year after year. The parrots relocate to a new breeding site every year based on where food (nectar from blooming eucalyptus trees) is most plentiful. They build their nests in tree hollows, which are most common in old growth forests.
The east coast forests of Tasmania must be thoroughly searched each year for nests for research purposes. Once a nest is located, the trees must be climbed in order to track the success of the breeding process. But as a result of this extensive research, new and astounding effects of forest loss on swift parrot breeding biology have been discovered.
This year, just as the parrots were starting to nest, the only nest was raided by a Sugar Glider and abandoned while I was experimenting with exclusion techniques. I painted the nest box to match the colors of the tree bark after moving it to a safer tree. This box is now occupied by the Eastern Rosella family.
Additionally, I have trimmed any shrubs and small trees’ branches so that they are below the possum guards on all nest box trees and that they are roughly 2 meters away from any nest boxes and possum guards horizontally. Top and bottom possum guards protected the lone, raided nest box, but a small, twigby branch nearby nearly touched the exposed trunk of the tree to which the nest box was attached.
As you have undoubtedly read from studies on the endangered orange-bellied parrot, sugar gliders love to snack on bird eggs, nestlings, and smaller adult bird species. Our property is home to many sugar gliders, and it’s likely that they visit each tree on a daily basis. The ability of gliders to fly from tree to tree complicates matters further when it comes to nest box security!
The majority of this year’s work has involved determining efficient exclusion techniques while the Wood Ducks and Parrots were trying to nest, and then quickly applying whatever seemed to be successful to all other active and inactive nest boxes where it was feasible. Two sets of Crimson Rosella chicks (2, 3) have flown from their nest boxes this year, and a third nest box has three young Crimson Rosella chicks. A fourth nest box has four fully feathered Eastern Rosella chicks. We are so happy about this! A set of Wood Duck ducklings, a group of Kookaburra chicks, and a Tree Creeper chick all successfully fledged.
Possum guards are located just above and below the nest boxes on lone, straight trees where the successful nest boxes are located. I added polycarbonate plastic panels to the top, sides, and base of one nest box that was next to a stand of bushy black wattle trees. I also covered the tree bark at the back of the box. The front of the nest box is where the Rosellas enter, so it must be left open. When I realized that the branch was too close to the nest, an egg had already been laid, so I had to work quickly to get this box done without disturbing the nest for fear of it being abandoned.
FAQ
Do sugar gliders eat other animals?
Do sugar gliders and birds get along?
What are the sugar gliders main predators?
Can sugar gliders live in a bird cage?