Hollow Habitats

4 May 2018

Stag tree

Stag & Veteran Trees Provide Benefits for Biodiversity

Tree hollows are cavities that form in the trunk or branches of old, living or dead trees, which provide important habitat for fauna. ‘Stag’ trees are generally old, dead trees that have lost their foliage but remain standing and more-or-less structurally intact. These trees are often considered an eyesore, but they are a crucial component of the natural environment. Stag and veteran trees are often referred to as ‘habitat tress’ as they have the capacity to develop natural hollows, which are critical for nesting, roosting, foraging and predator evasion behaviours by an abundance of native species.

Large and locally native trees such as the Jarrah, Marri and Tuart as well as many introduced species, have the potential to be hollow-forming. Tree hollows arise as a result of limb loss, ageing, fungal decay, bushfire or damage often through insect or bird attack. Whilst there are a myriad of ways by which hollows may form, it is a lengthy process and you will be hard-pressed to find any hollows in a tree younger than 100 years old!

Within the Perth region lives a huge variety of native animals that depend on tree-hollows for nesting and roosting habitats. Birds species such as the Carnaby’s and Red-tailed Black Cockatoos, Tawny Frogmouths, Boobook Owls, Australian Owlet-nightjars, Australian Ring-neck Parrots, Pardalotes and even some Ducks, as well as mammals such as Brush-tail Possums, the Gould’s Wattled Bat, and the White-striped Free-tail Bat are just a few examples.

Sadly the Swan Coastal Plain has lost roughly 90% of its original vegetative cover, meaning that any remaining naturally occurring tree hollows have become highly sought-after and increasingly rare real estate! In addition to dealing with habitat loss our native animals must also contend with introduced species such as the Rainbow Lorikeet, Laughing Kookaburra and the European Honey-bee who all compete (often ferociously) to occupy available hollows.

The installation of artificial nest-boxes, ‘Cockatubes’ and bat-roosting boxes have proven successful in some cases and are an innovative means through which we can increase habitat for hollow-nesting species, however recent studies have demonstrated perhaps unsurprisingly, that natural hollows are selected preferentially over artificial hollows, by many species. Retaining existing established stag or veteran habitat trees, rehabilitating degraded natural areas and actively increasing tree canopy cover are critical to ensuring tree-hollow habitat preservation and protecting local biodiversity.

Written by:

Sarah-Jane McMahon

Environmental Education Officer | City of Melville

We would love to hear if you are lucky enough to have hollow-nesting species or any other unique native wildlife visiting your property! What sort of backyard biodiversity do you have?

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