Photo source: Julian Robinson
While most owls limit themselves to prey up to 20% of their body weight, Powerful Owls go after many arboreal mammals such as possums, gliders, and juvenile koalas, which can be 50 to 100% of their body weight. That is about 10x the body weight to prey ratio of other owls.
Here’s an Australian Geographic article about Powerful Owls worth a read with some more photos, including this low power version.