Some very interesting info there Stephen, thanks for clarifying. Will certainly keep that in mind when flagging trees.

Yesterday, I spoke to the arborist Peter Castor of Tree Wise Men Pty Ltd about the use nails and screws to fasten tags (or something similar) to trees. He said that the widespread claim that nails and screws, including copper ones, can impact on the health of trees is an urban/rural myth.

In relation to Amy's point about the accuracy of GPS in identifying the posiition of individual trees habitat trees in need of protection from the bulldozer:

I've learnt never to rely on unsupervised 'dozer drivers avoiding marked habitat trees when clearing vegetation. An ecologist should always be present on site to ensure that relevant habitat trees are retained during dozer works. This is usually written into the conditions of approval by consenting authorities. That ecologist should be able to recognise the habitat tree(s) within a radius of several metres of the GPS reading, especially if he/she is the one that took the GPS reading in the first place. 

The irony is that you cannot stop a developer from bulldozing a tree that contains an active nest, if the animal species started nesting in the tree after approval to clear vegetation has been granted, unless that species is a threatened species. I recently sought advice on this issue from DECCW when a developer wanted to push over a tree containing a White-faced Heron nest with chicks (one of many trees that were cleared on site that day). Because the White-faced Heron is not a threatened species, and because the breeding pair had started nesting in that tree after approval for its removal had been granted, the local council, DECCW or the ecological consultant did not have the legislative authority to enforce a postponement of the developer's clearing of the land. I understand that the heron chicks were rescued by a WIRES person before the tree was pushed, but I have no idea if they survived in the longer-term.

The point that I made at the workshop was that if birds are observed nesting in a tree hollow (or any other part of a tree, e.g. canopy), then that tree should not be flagged with surveyors tape or other identifying item to mark its position. It's well known among ornithological researchers that brightly colour surveyors tape attracts the attention of avian predators such as currawongs, butcherbirds and ravens, epecially if parts of the tape are wind blown, which can lead to th detection and  subsequent predation of nestlings that are in that tree.

I'm not sure if marking tree trunks with spray paint has the same effect, but I never mark trees that contain active nests because of potential predation risks.

I've heard the old anecdote that driving a copper or zinc nail in a tree was a way to slowly kill it and get it removed under TPOs, but not personally seen a tree dead from such. More likely was a drill and a shot of undiluted Round-Up.

For that reason tho, I don't use galvanised nails for mounting trap shelves, and don't use nails to erect nest boxes. Instead I use the plastic coated wire and spring trick - tho this means selecting trees with a suitable limb to throw the rope over to stop the box sliding down the tree.

Having not been at the workshop, I to would be interested to know Stephen's rational. Not quite sure why putting flagging tape, paint or distinctive tags on a tree would encourage predators, as opposed to the predators own ability to follow scent trails and locate the prey themselves.

RE nails, excluding copper ones (which may in fact be an urban myth), I've never had any issues with trees dying or suffering from using nails to put up nesting boxes, screws to fix permanent ladders to access sites I’ve repeatedly trapped at [cage traps on wooden brackets], or nails to secure wooden ladders to access cubby houses. I use galvanised nails/screws to reduce the impact of the nails rusting, thereby requiring repeated replacing. I would be guessing that the plants themselves have their own defence mechanisms and secretions they employ to "attack" the nail/screw which would ensure the plant doesn’t suffer or die in the long run. A classic example of this would be those trees used on farming properties as “fence posts”. With these I’ve never seen any that have died due to the presence of barbed wire. A lot of the time the tree has in fact grown around the wire, the plant itself thriving. I’ve also seen a lot of trees that have been hit by cars and partially ringbarked survive. Based on these examples, I’m not sure why one or two screws would affect these plants. I think this is another one of those anthropomorphic sweeping statements that a lot of supposed "educated" people tend to sprout without actually looking at the real world and the ability of a large number of species to be tolerant of humans and their actions.

Hi ECA

I would like a more detailed explanation from Stephen as to how marking trees encourages predators, having not encountered this issue before.  Usually, the marking of trees with paint and flagging tape is the beginning of the end for these trees, so the tree occupants are likely to have more to worry about than predators.  However, if you are doing a habitat tree survey for an audit / LES study / BioBanking Assessment??, I normally don't mark them with anything.  I used to attach those lightweight aluminium tags which I nailed to the tree.   However, the tree huggers told me I was destroying the tree by use of nails (galvanised clouts), so I disbanded this practice.  So, I have taken their advice, but this raises a question, do nails significantly impact on health of trees ??  My personal thoughts are no, based on use of tech screws and other fastening items to attach nest boxes, traps, etc to trees.  For instance, several hundred nest boxes have been installed at various locations with the use of tech screws, and the trees seem okay, 15 years on.  Eventually, the tree gets back by swelling around the screw and eventually breaking the screw by pressure. 

These days I now attach things to trees without the use of fasteners such as screws, nails, etc.  I dont think I answered Amy's question, and instead created a new one, but can anyone expand on whether nails, screws or other fasteners that are driven into the tree impact on the health of the tree.

Michael Murray

At the tree hollow work shop Stephen Ambrose mentioned in his presentation that you should not mark habitat trees as this encourages predators, but instead should use gps readings. I had a discussion with others about this at the workshop. We are often asked to mark habitat trees with spray paint, flagging tape or plastic or metal tags, so that a surveyor can get more accurate positions for the trees, or for the bulldozer driver to know which trees to leave and be careful of. Often GPS readings are not accurate enough to avoid confusion, especially when different people are referring to the same trees, and gps readings would not be usefull to a dozer driver.

Would anyone like to comment on this?