NRM top tips - May: Protect hollows

Trees with hollows - both dead and alive - are a habitat requirement for many of our native animals. According to the research of Gibbens and Lindenmayer in 1997, around 17 per cent of birds, 42 per cent of mammals and 28 per cent of reptiles in south eastern Australia use hollows - including possums, gliders, microbats, parrots, owls, ducks, rosellas, kingfishers as well as many species of snakes, frogs and skinks.

Hollow formation occurs mainly in eucalyptus species such as gums and box trees. River Red gums (Eucalyptus camaldulensis), commonly found on cotton farms, are a well know producer of hollows. 

Small hollows suitable for small animals like eastern pygmy-possums take about 100 years to form.  Hollows suitable for larger animals like brushtail possums and owls take over 200 years to form. Therefore removal of trees with hollows from the landscape can have profound impacts on the survival of many species.

Anna Madden and her husband Steve have a cotton farm near Wee Waa on Gunnidgera Creek.

A diverse range of wildlife utilise the farm for food and habititat - many of which can be observed in old tree hollows along the creek and in the travelling stock route adjacent to the farm.

“I have seen many different species of owls and parrots nesting in these hollows as well as snakes such as the iconic carpet python and smaller pale headed snake," Anna said.

“As well as the pleasure I get from having these species on our farm, I see value in the contribution wildlife like microbats and owls provide towards our natural pest control. They are another tool in our toolbox of pest management options”.

In 2013, as part of a Cotton Catchment Communities CRC and Namoi Catchment Management Authority collaboration, Anna participated in a on-ground project to install microbat and owlet boxes in areas on their farm where hollows were limited.

“The artificial microbat boxes have been utilised at different times over the years, and we've had to re-install them a few times as the trees have grown," Anna said.

“We have a number of different species of microbats on our farm and being able to provide additional habitat can only add value to our natural pest control and maintaining our farms balance between agriculture and the environment."

• Maintain a range of old hollow-bearing trees, including dead ones.  It is best to leave at least five per hectare.
• In areas where trees with hollows are limited, erect nesting boxes
• Encourage regeneration to ensure the next generation of hollow bearing trees