You are currently browsing the tag archive for the ‘tree hollows’ tag.

The palm trunk above the Marrickville Golf Course Club House is the new home of a pair of Sulphur-crested Cockatoos.  The white dot is a cockatoo.

Gone!

On 19th August 2017, I posted about a palm tree trunk behind the Club House at Marrickville Golf Course that was being used as a nesting hollow by a pair of Cockatoos.   See – http://bit.ly/2wboFtx

I rode past today & it was gone.

Advertisements

The palm trunk above the Marrickville Golf Course Club House is the new home of a pair of Sulphur-crested Cockatoos.  The white dot is a cockatoo.

Squee! Here I am!

I watched the decline & eventual death of an old palm tree behind the Marrickville Golf Course Club House with some sadness.  Trees like this don’t get replanted in my experience.

Recently, I saw something happening at this tree that delighted me.

What is left is the trunk, which is quite tall.  A pair of Sulphur-crested Cockatoos saw this trunk as an ideal home.  I presume they made a new hollow or modified a hollow that was starting to form with the shedding of the fronds.  Whatever way it happened, it is now a perfect hollow with a balcony & a clear view of the Cooks River & we all know the power of water views.

Behind the trunk is a large mature fig tree providing them a safe place to survey the area for any danger before entering the hollow.

In true Cockatoo style, once they realised they had my attention, the pair posed & acted out for my camera until I had enough & moved on.  They seem very proud of themselves.

Even though this tree is dead, it is an incredibly important asset in the Cooks River Biodiversity Corridor.  Trees with hollows are rare in the area, so every attempt must be given to retain this trunk.  It should not be removed to “clean up the area” or similar.

Sulphur-crested Cockatoos nest in tree hollows.  Once they find a suitable hollow they stay there indefinitely.   The chicks they rear will remain with the parents as a family unit.

So, for me, discovering this hollow made up for the loss of yet another tree.  Hopefully, a new palm will be planted behind the Club House.  In the meantime, people who are aware of this pair, can have an occasional look to see if they can spot them & any chicks they are rearing.

To my mind, the Club House has been blessed with some mascots to screech & cavort above them.  What fun!

A great home with a big fig tree behind and the river in front.

Bat box built especially to house microbats.

New research published 28th July 2017 titled, ‘Bat boxes are not a silver bullet conservation tool’ is a bit alarming when it comes to the future of urban bats.  They are losing habitat at a rapid rate.  Trees with hollows are scarce enough as it is, but all run the risk of being removed by development.  Many of us think, myself included until recently, that providing a bat house will help.  However, this research has found the opposite is the reality.

The abstract says, a long-term bat-box monitoring project in south-eastern Australia, box occupancy was dominated by one common and widespread urban-adapted species, Gould’s wattled bat Chalinolobus gouldii.   In contrast, the 13 other bat species in the area made little or no use of the boxes.  Policymakers, land managers and conservation professionals working in the field of biodiversity offsets should be aware that bat boxes are unlikely to compensate adequately for the broad-scale loss of tree hollows caused by various forms of human disturbance.”  See – http://bit.ly/2hlXNRj  

Just one more reason why we must do our best to save trees, especially older trees.  The information on the time it takes for a tree to develop hollows ranges from 100-150 years.  Until recently, most articles I read stated that 150-years was the average time a tree takes to produce a hollow.  The difficulty of achieving this is obvious.  If there is no suitable hollow, there is no breeding.

Nesting box along the Cooks River in Earlwood.

$200,000 was spent trying to protect wildlife impacted by the Southern Hume Highway Duplication project in Southern NSW.  See – http://ab.co/2uDf9fl

587 nesting boxes were installed to replace the 587 trees with natural hollows that were felled as part of major tree clearing between Holbrook and Coolac to build the highway.  The nesting boxes were to help the Superb parrot, the Brown treecreeper & the squirrel glider deemed threatened or in need of assistance.

NSW Roads and Maritime Services commissioned the nesting boxes, as well as a 4-year follow-up study to see whether the boxes were being used.  The boxes were checked 3,000 times over the four years.

The follow-up study found the project had failed.

“There will be some populations of these species that basically won’t do well now because they won’t have the nesting resources and they won’t have those resources for the next 200 to 300 years.  We need to make sure we don’t make those mistakes again.” ~ Professor David Lindenmayer, Australian National University Canberra.

Trees take between 80-150 years to develop hollows, so changes in tree management is needed if hollow-dependent wildlife are to survive.  We cannot feel confident that nesting boxes can be offered as a substitute for a natural tree hollow.

No hollow means no breeding.  No breeding leads to extinction.

Showing two of the new habitat trees - one on the left and the other in the foreground with the sign on the trunk.

Showing two of the new habitat trees – one on the left and the other in the foreground with the sign on the trunk.

Last October the Inner West Council posted that they created three new habitat trees in Mackey Park Marrickville South.   We walked the whole park, but unfortunately were only able to find two of the trees.  The trees we found were between the shared path & the wetland area.

Habitat trees are trees that have caused a safety problem by dropping branches. Rather than removing the tree, the tree is killed by ringbarking.  Then the branches are cut open & a cavity created with a chainsaw to create nest boxes & other kinds of hollows.

A large amount of Australian wildlife will not breed if they do not have access to a hollow, so retaining the structure of mature trees is vitally important.  See – http://bit.ly/1ASqhzz

Council said they created five nesting boxes in these trees.  Three for Red-rumped parrots, one for Gould’s wattled bats (microbats) & one for a Brushtail possum.

They also plan to mulch & landscape with local native plants under & around the trees in the near future.  Good one Council.

Showing one of the nesting hollows.

Showing one of the nesting hollows.

The dead habitat trees are visible from some vantage points

The dead habitat trees are visible from some vantage points

‘Habitat trees’ are trees that have been killed because they are considered dangerous due to dropping limbs or other issues, but left on site.  Their canopy & their branches are removed.  The trees are ringbarked & artificial hollows are carved into the remaining wood.  Sometimes, nesting boxes are also attached.

The idea is that even though dead, the trees continue to provide habitat for hollow-dependent wildlife.  About 350 Australian animals use hollows for either roosting or nesting.  It takes around 100-150 years for a tree to even start developing hollows, so our wildlife is at a distinct disadvantage with tree hollows being very scarce across Australia.

I was really pleased to see the changes around the ‘habitat trees’ in Sydney Park.  I last wrote about these trees here – http://bit.ly/2fQ9DkG

The area around both trees has been extensively planted making what I consider viable habitat for a range of species, especially small birds. Instead of two highly visible standing dead trees, the City of Sydney Council has surrounded these trees with densely planted living trees, shrubs & understory plants. To me it looks like the bush.

I am not good at estimating distances, but my guess is that it is at least 25-metres of thick bush around the two habitat trees.  Already a number of living trees are the same height as the two dead trees.  This provides supreme cover & safety for any wildlife who are using the man-made hollows.

I think what has been created here is perfect.  Real habitat has been provided for wildlife & we are not left with what could be considered an eye-sore of looking at two heavily pruned dead trees.  The trees have blended into the new landscape and are not the only thing ones eyes focus on.

You can sit in comfort at a number of places near this area & watch & listen to the birds making it great for bird photography too.

They almost disappear from other angles.  I love that City of Sydney Council plants densely in some areas.

The dead trees almost disappear from other angles. I love that City of Sydney Council plants densely in some areas.

This tree hollow in Putney Park looks like it is straight out of a fairy tale. It is terrific that the tree has been allowed to stay.

This tree hollow in Putney Park looks like it is straight out of a fairy tale.  It is terrific that the tree has been allowed to stay.

We went to an interesting workshop yesterday called, ‘Hollows as Homes’ organised by Marrickville Council before it became Inner West Council.  The workshop was presented by Dr Adrian Davis, who did his PhD on tree hollows.

Tree hollows are in severe decline.  It can take a tree anywhere from 50 to 150 years to develop a hollow suitable for wildlife to use as a home.  It can take up to 200 years for a hollow to form suitable enough for a large bird such as a powerful owl.

Trees are being chopped down before they create hollows & the lack of tree hollows has been classed as a “Key Threatening Process to biodiversity in New South Wales.”

We have no ‘primary excavators’ in Australia.  A woodpecker is a great example of a primary excavator.  They can quickly create quite large holes in trees while searching for food.

In Australia, decay is needed to create a natural hollow in a tree.  Decay comes after the sapwood has been breached.  This happens only after a tree has been damaged by lightning, wind, bushfire or mechanical damage.  Fungus enters & slowly over decades creates the hollow, which then becomes a suitable home for a range of wildlife, including birds, microbats, bees, lizards, spiders, possums, frogs, snakes & gliders.    Six to eight species may be competing for a single tree hollow.  Tree Hollows also provide drinking water for wildlife, which in itself is important.

As we know, public trees that develop decay are chopped down.

Over 300 native invertebrate species in Australia are dependent on tree hollows to breed.   No hollow for a home – no breeding.  A shortage of tree hollows leads to a decline in species numbers & in some cases, resulting in an endangered species.   It is easy to see how vital tree hollows are to the native wildlife of Australia.  A shortage of hollows also results in a predominance of specific species that are string enough to gain ownership of the hollow.  Locally, these are sulphur-crested cockatoos & rainbow lorikeets.

I did learn something interesting about cockatoos.  They may sleep as far away as the Blue Mountains, but fly to Sydney every day.   I did not know they could fly so far.  Makes me think about the cockatoos who live their life in a cage.

Dr Davis said that in the Central Coast region, 54 species use tree hollows & 13 of these are endangered.    

The ‘Hollows as Homes’ program is the first of its kind in Australia & has the intention of collecting data for many decades.

“Nest boxes and cut-in hollows are often used in areas lacking natural tree hollows, however we don’t know a lot about how animals use this substitute habitat in place of natural hollows. Many animals have specific attributes that they like in a hollow, consequently some animals may not use artificial hollows. For this reason it is important to know if nest boxes and cut-in hollows are attracting the desired animals, or, if they are being used at all. The Hollows as Homes project aims to conduct the first landscape scale assessment of tree/nest box/cut-in hollow distribution, type and wildlife use.”

The program is looking for people who are willing to watch a tree hollow for 10-minutes once a fortnight & then log their observations on the website.  This is a perfect opportunity for schools that have nesting boxes to become involved.

The website has clear instructions about how to get involved & what information to provide.  They are not asking for much.  It would be especially easy for those who have a tree hollow or nesting box in their garden.  Sit & have a cup of tea while watching the box for 10-minutes & help in the creation of data that will be immensely helpful for generations.

If you don’t have a tree hollow in your garden, then you can choose one or more trees locally that do & observe those trees.  The researchers do not care where the tree is, though they do not know how many trees with hollows or nesting boxes there are in private gardens, so this information will be very useful.

If you missed the training at Marrickville, the website shows upcoming workshops & all are free to attend.  For more information see – http://bit.ly/1U6x70v

I was surprised to find a nesting box close to a seat that I sit on at least weekly.    This might be my choice for the program.

I was surprised to find a nesting box close to a seat that I sit on at least weekly.   This might be my choice to observe for the program.

First sight of the habitat trees from across the lower pond.

First sight of the habitat trees from across the lower pond.

A closer view

A closer view. Both are still very tall trees.

City of Sydney Council has recently created two ‘habitat trees’ in Sydney Park. Both trees are Eucalypts & are located close to the lower pond.   They are surrounded by other tall trees & so would make attractive homes for wildlife.

A significant difference from the ‘habitat tree’ created by Marrickville Council in McNeilly Park is that the branches have not been ring-barked – at least it had not been done when I saw these trees.  It appears that Sydney Council has created more holes in each tree than the one in McNeilly Park.

Showing the damage on one of the trees.

Showing the damage on one of the trees.

Like Marrickville Council, the City of Sydney Council is also using these trees as a demonstration for professionals on to how to create nesting hollows for birds & animals.

I really like this movement to retain trees that would have been removed previously.   The idea is to mimic dead trees found in the bush.

The more I read about dead trees the more I realize how important these old dead trees are to the ecology of the environment.   Standing dead trees in the bush are called snags & stag trees.

Only old trees have hollows & these trees often need to be 100-150 years old before they start creating hollows.  Eucalypts start creating hollows after dropping branches & we know that once branch-dropping starts, the tree is removed for the safety of the human population.

“Australia-wide, 15% of all land birds use hollows. These 114 species include parrots, owls cockatoos & lorikeets, ducks, treecreepers, owls, owlet-nightjar, kingfishers, pardolotes, martins & woodswallows.”  ~ Sourced from Wildlife Notes, Department of Conservation & Management April 2005.

One of the least known characteristics of Australian animals is their high utilisation of tree hollows. For example, the proportion of Australian animals that use tree hollows is three times greater than in North America & twice as great as in South Africa.

About 350 Australian animals use hollows for either roosting or nesting. This includes:


  • half of our small bats,
  • nearly 90% of our parrots,
  • all of our gliders,
  • all but one of our owls
  • all of our tree-creepers.

Nearly 20% of our birds use hollows in some way. For 60% of these, hollows are essential.” http://www.ozbox.net.au/anim&holl.htm

Of the 22 species of bats that have been recorded to utilise tree hollows in NSW, 10 of these are listed as threatened. (Gibbons & Lindenmayer 1997).

Repurposing trees that would have been removed so that they become useful for wildlife is a great idea. Tree hollows in urban environments are very rare.  I look at trees all the time, but only know of three trees on public land in Marrickville LGA that have natural hollows. I applaud this move to help wildlife & improve on biodiversity by both Councils.   It will be interesting to see what wildlife do take up residence in these hollows.

Sign on tree

Educational sign on tree

The back of the nesting hollows.  To show the front would have meant facing the sun,

The back of the nesting hollows. To show the front would have meant photographing into the sun.

Another view.  It's hard to see the hollows, but the more I looked, the more I spotted.  They are on the tips of branches as well as multiple hollows along branches.

Another view. It’s hard to see the hollows, but the more I looked, the more I spotted. They are on the tips of branches as well as multiple hollows along branches.

A hollow has been made at he end of many of the branches.

A hollow has been made at he end of many of the branches.  It’s hard to see, but it is there.

 

Archives

Categories

© Copyright

Using and copying text and photographs is not permitted without my permission.

Blog Stats

  • 513,697 hits
%d bloggers like this: