Trees with hollows


Many animal and bird species are dependent on tree hollows, as nest sites during breeding season, or as year-round retreats and roosts.  

Here is an extract from a conservation management note published by the National Parks & Wildlife Service in 1999.

  • Hollow formation is dependent on a tree’s history, its species and location. Generally, small hollows with narrow entrances suitable for small animals such as the brush-tailed phascogale (Phascogale tapoatafa) and the eastern pygmy-possum (Cercartetus nanus), take about 100 years to form. Hollows of a medium size and suitable for animals such as parrots will take around 200 years to form, and the larger and deeper hollows occupied by glossy black cockatoos (Calyptorhynchus lathami) and other larger animals such as masked owls (Tyto novaehollandiae) can take a lot longer (Mackowski 1984; Menkorst 1984; and Scotts 1991). 
  • Valuable hollows for wildlife are generally found in mature and dead trees. Openings range from as small as 2 cm to as large as 75 cm, with depths ranging anywhere from 10 cm to 10 metres (pers. comm. Kavanagh). 

Some of the facts about the formation of tree hollows, and the extent to which species depend on them, may come as a surprise. The short paper is well-worth reading in full - click here to download as a pdf.

The hollows below are all found within two hectares of forest in the south of the Atlas of Life region.

In response to several suggestions, we are in the process of enabling the recording of 'trees with hollows' on NatureMapr.

This feature will be expanded and refined further over coming weeks.


In the meantime, be on the lookout for hollow-bearing trees, document your discoveries, and add your sightings to NatureMapr.

For now, there is a category under 'Plants', 'Other trees', and 'Trees with Hollows'. As we refine the categorisation, your records will be migrated accordingly (so nothing will be lost by starting to record your sightings now!)

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If you would like to receive an email alert regarding progress on this new feature, please provide your contact detail (below).