The need for tree hollows

Tree Hollows are disappearing.

Prior to European settlement, the vegetation covering the Kedron Brook catchment would have contained many mature eucalypt and paperbark trees. These trees live for hundreds of years; as they age, damaged or broken limbs form hollows.

Tree hollows provide essential nesting sites for many types of native animals including possums, gliders, birds, reptiles and bats.

Due to extensive clearing of native vegetation large trees have been lost and therefore the hollows available to fauna greatly reduced.

Tree hollows as nest sites

Mature forest trees are still present along many sections of Kedron Brook. Sulphur-crested cockatoos use hollows in tall eucalypts at Grinstead Park for nesting. At Kalinga Park and Hickey Park, hollows in old paperbarks are used by Scaly-breasted rosellas and Rainbow lorikeets for nesting.

Alternative nesting sites

Some hollow using animals have found alternatives. Possums will readily find shelter under eaves of buildings. Insectivorous bats, many of which are only a few centimetres in length, use hollows under bridges or roost under power pole caps.

Nesting Boxes

The potential shortage of nesting hollows for local fauna has been recognised for some time. Nesting boxes have been erected in trees throughout the catchment to provide additional nesting resources. These have had mixed success.

Rainbow lorikeets and Galahs have moved into some boxes. Some of the breeding pairs appear to visit the same box each year. Birds do not use many of the nesting boxes, possums may take up residence or the nesting boxes are unoccupied.

Some nesting boxes have been occupied by Noisy miners, a gregarious and aggressive bird that is increasing in numbers in southeast Queensland. Use of nesting boxes by these birds is at the expense of less common native species.

Boxes for bats

Recently, boxes have been installed that are designed specifically for insectivorous bats. These are a ‘slim’ box with a downward facing opening of only a centimetre or so. Bat nesting boxes have been set up as part of a Griffith University project to investigate the insectivorous bat fauna in the Brisbane area.

You can help

Tree hollows are an important resource, if you have a large native tree in your yard or know where there are trees with hollows – protect them where possible.

Build a nesting box and secure it high in a large tree in your garden