The main breeding season for most of our native birds is just around the corner, with courting and nest building already underway in some species and areas of Northern Victoria. The story of the Pizza Oven Kookaburras highlights the importance of adequate nesting hollows for many species.

Last year in November, I was called out to three freshly hatched Laughing Kookaburra chicks who had hatched in an unusual place. The parent birds had decided that an outdoor pizza oven in the yard of a private residence was the ideal nest spot. Unfortunately, it turned out to be less than ideal. The oven was located right beside a driveway with vehicles entering and leaving continuously. This caused the parent birds to be disturbed every time a car passed, leaving the new chicks unattended and cold. The concrete floor also added to the 'nest' being very, very cold.

When it was discovered that two of the chicks had just hatched, a close eye was kept on the activity of the parent birds around the nest. Luckily, they were checked upon when there was concern that the parents were not attending to the nest as they should and the chicks were found almost dead, stone cold and pretty lifeless. The following day, the third and final egg hatched and this chick too, almost didn't make it. The three chicks were gathered up and kept warm until I got over there to pick them up. They would not have survived if left in the pizza oven.

The residence where the pizza oven is located is in Rushworth, Northern Victoria. The surrounding natural bushland is lacking natural nesting hollows, especially ones of considerable size to accommodate larger species such as Kookaburras. To understand why this area is deficient in hollows, you need to know a bit about the dynamics and history of the surrounding forests.

Rushworth's forests consist of Box-Ironbark Woodland. These trees are extremely slow growing, with a growth rate of around 0.35cm each year, or roughly a centimetre every three years.

At the time of European settlement around 13% of the state of Victoria was covered with extensive forests of Box and Ironbark trees, including the unique understory vegetation that go hand in hand with these types of forests.

As a result of clearing the forests for agriculture and mining, harvesting them heavily and continuously for firewood, posts, sleepers and sawlogs, sadly, there is only about 17% of the original Box-Ironbark forests remaining. Most of the remaining trees are on public land and are highly fragmented. This drastic reduction in the forests combined with the extremely slow growth rate of trees has caused a great imbalance in the natural dynamics of Box-Ironbark Woodlands which has now become quite obvious.

The problem is quite simple, the number of large, old growth trees has become tragically low, these trees being the target for harvesting over many, many years. Studies have shown that originally, the number of large, old growth trees in these forests would have been at a density of around 30 per hectare. The spaces between these century old trees would have been filled with medium and small sized trees which would ultimately replace the old giants as they eventually died and let in more light.

Now, large, old growth trees are very rare in the forests and 99.6% of the trees are below 60cm in diameter. This is less than half the size of the largest trees, which are now mostly restricted to fragmented areas, usually along roadsides, public land, waterways or on private land.

This is the reason why there is a serious lack of hollow bearing trees in the Rushworth area and is very likely the reason why these Kookaburras chose the closest thing they could find to a suitable nesting hollow, which happened to be an outdoor pizza oven.

The story of the little Pizza Oven Kookaburras turned out to be a happy one in the end, only due to intervention. All three were raised successfully at Bohollow as hatchlings and went on to be released from our Bunbartha shelter with other juveniles and some adult birds who could not go back to their previous location. I guess it depends on how you look at things. The chicks were hatched and raised successfully through our eyes, but from the point of view of the parent birds, they lost every single chick and failed to have any young that season. This is a very real and a very serious problem, not just in Box-Ironbark Woodland but in all native forest types, all over the state.

Habitat loss, especially the loss of old growth, large, hollow bearing trees is one of the major driving forces behind the lack of biodiversity and species decline in many areas and in some areas it has lead to local species extinction. Hollow bearing trees are vital for wildlife species who use hollows for both nesting and roosting. Trees take at least 100 years or longer before they may acquire hollows.

It is absolutely critical that we protect large, hollow bearing trees as well as younger, future hollow bearing trees. Older, larger trees also provide more fallen timber which is also critical for the survival of many woodland species. It has been proven that species diversity radically declines in areas where there is little or no fallen timber in the understory. The main reason for areas to be deficient in fallen timber is firewood removal. Grazing also greatly disturbs understory vegetation and ground litter which in turn threatens ground dwelling and foraging species such as the Bush Stone-curlew, Woodland Blind Snakes and numerous other species. If remnant bushland becomes so fragmented and degraded, when stress events such as drought, fire or flood occur, this can push species even further towards serious decline and ultimately extinction as they do not have sufficient areas of habitat to recover in.