Deryk, I wish it was so simple as you explained. Reintroduction of Greater Gliders into Royal National Park may indeed increase the breeding potential of forest owls in the area. However, there are other factors that also contribute to the breeding success of owls, e.g. the availability of suitable nesting hollows. If there aren't enough hollows (and I don't know if that's the case), then it doesn't matter if there are additional prey items, the local owl populations are unlikely to increase significantly in size.

Greater Gliders are not the only food source for owls and if local owl populations increase in size as a result of the reintroduction of the gliders, then there will be changes in predatory pressures on other prey species, thus potentially upsetting the ecological balance of the national park's ecosystem.

So your idea is worth thinking about, but one needs to think through the potential ecological consequences with care, which is not be easy to do.

I would "argue" that the Koala, is (generally) at the top of its particular food chain, and therefore its numbers are not controlled by predation. Something like the Greater Glider is a "middle rung" speices in the food chain, this rung now being absent due to human influences. As opposed to issues such as an increase in Koala numbers on Kangaroo Island, resulting in these animals having to be "culled"/managed, I dont think a species such as the Greater Glider would ever expand its population numbers to the point that they present a threat. What is more likley to occur as Greater Glider numbers increase is, that predator numbers (including those threatened owls present in Royal National Park [Royal]) would also increase. Increases in predator numbers, including speices such as the Powerful and Sooty Owl, would assist with the recovery of these animals, an overall objective of the DECCW Large Forest Owls recovery plan. Interesting to note, reading the Large Forest Owls recovery plan that, for the Sooty (a speices known to be present in Royal) and  Masked Owls both of these species "have a higher reproductive potential when food is unlimited " (recovery plan page 11 and 12). So, conversely, by humans reducing the food supply due to arson burns, we have ineffect reduced the reproductive potential of these owls. Therefore, dont we have an obligation to rectify this situation???

Given the recent findings of CSIRO presented at our conference in regards to the impacts of climate change and the need to encourage genetic diversity to cope with the impending ecological catastrophe, and similar findings presented at the NSWRZS conference, I am inclined to thinking that our best bet to not place all our money on one horse in one race, but to spread the risk. Hence in this instance where the Glider is currently absent, but suitable habitat is available, may have merit for introduction from outside sources - if those current threatening processes are manageable. In one of the recent Wildlife Research journals (or was it Aust Zool? - cant recall), I was surprised to find out so many of Victoria's Koala populations are a result of middle 20th century translocations to establish new populations. Hence I am starting to think we can't be too choosy in some circumstances at least.

I have just been involved in a project where bushland on the south coast of NSW is to be cleared. This bushland supports good populations of Greater Gliders. Greater Gliders were once common in the Royal National Park but a high intensity wildfire, the result of arsonists, that swept through this conservation reserve in 1994 caused the local extinction of this species (i.e. post-1994 there have been no records of Greater Gliders in this conservation reserve). This component of the ecosystem, which not only offered foraging resources to owls (several threatened owls are known to occur within the Park) but also had other biological function re plants, was lost. If I was to recommend that the Greater Gliders from my south coast study area be collected and released into the Royal National Park I know I'd be shot down in flames. Genetics differences would be the first thing thrown at me followed by a load of DECCW bureaucratic bull. The problem with the genetics argument is, there are no Greater Glider populations in the Park now so what does it matter?? The reintroduced individuals won’t breed and mix up the Greater Glider genetic stock as there is nothing for them to breed with. The species role in the ecosystem is vacant, why, as we try to conserve our ecosystems, don’t we take direct action to fill this gap when we have the means and power to do so??? This is particularly the case as, a large number of the animals within my south coast study area will die as trees are felled in front of the bulldozer blade. Instead of “wasting” this material (i.e. the Greater Gliders) shouldn’t we collect it and relocate these animals into a conservation reserve in which the Greater Glider was previously recorded? Thoughts?