Tree hollows at a premium

Australia has the greatest variety and number of animal species that are reliant on tree hollows for their survival.

Nearly 30 amphibian, 80 reptile, 115 bird and 80 mammal native Australian species use tree hollows for diurnal or nocturnal sites for rearing young, shelter, roosting or feeding. Many hollow-reliant animals are recorded as rare, threatened or vulnerable. Many invertebrate species that are essential to a healthy ecosystem are also hollow-dependent.

 

Most animals that are obligated to use tree hollows have no other resource. A few will adapt to a crevice in a building or a rock, or similar. The little Striated Pardalote for example, has adapted to using hollow cross beams on power poles. 

 

The best trees for forming hollows are the eucalypts and many of them do not begin to form useable hollows until they reach 120-150 years of age. 

 

 

A further element of pressure on the use of tree hollows is the adoption by pest species – Common Mynas, Starlings, European Honeybees, etc. 

Many birds will defend their ‘hollow territory’. Some will guard their chosen hollow for some weeks before it is required for egg-laying. During a recent one hour visit to Picnic Point at Longwarry North, the following birds were seen entering, leaving or guarding their selected tree hollows – Eastern Rosella, Rainbow Lorikeet, Galah, Little Corella, Sulphur-crested Cockatoo and King Parrot.

There is an ongoing process of decline of mature, hollow-bearing trees due to dieback, land clearing, bushfire, firewood collection, lack of recruitment, and urbanization. Trees with hollows, even dead trees, need special protection and we urgently need to be planting indigenous tree species that in time will form natural hollows.