1999 (March) Eight old Camphor laurel trees - planted at the N-I School in 1919, are closely observed by independent scientists to be appearing highly stressed, all with symptoms of severe leaf blistering (bubbles over leaf surface), as well as irregular leaf-curling, and in-folding, all across the outer tree-canopies. Only two other small (5) plantings of equivalent-aged Camphors reported elsewhere on Norfolks main island. All thirteen (13 total remaining)Camphor trees average 2ms diameter at 80 years of age.
2005 (January) In three-directions around the N-I Central School, young Camphor trees up to three metres tall are observed, seedlings of between one and five years age (estimate), arising through hedges, and disturbed roadside sites; believed to have been moved around by an unidentified bird-vector species, because of the dense aggregation of newly maturing Camphors in a creek catchments headwaters(Town Ck.), well clear of where any humans or other fauna would have traveled, at 0.6 kms distant from the School trees;
The original planting of more than 20 Camphor laurels is confirmed as having come from Sydneys Department of Education and the Royal Botanic Gardens; The School originally planted 20 Camphors but in 1955, and 1995 a total of twelve were removed, mainly because of watertank pollution, and the rusting-out of building-gutters also attributed to the bi-seasonal deposition & rotting of Camphor laurel leaf detritus.
Bird Species Vector: Hypothesised to be Porphyrio porphyrio the Swamphen, which has built-up a significant population-size on-the-island, and yet only known to breed in the lower catchment of the Town Creek swamplands near Kingston.
2005 (August) 200 or more Camphors now found in seven locations across the centre of the main island, the apparent commencement of , or foundation mother trees for a future -predictable population explosion as occurred on similar volcanic soils across NSWs Northern Rivers between 1955-2005 (50 yrs invasion).
Close inspections reveal three generations , or age-class groupings of Camphor laurel seedlings across the centre of the main island :-
Individual Camphor trees of all-three age-class groups defined above are found to be most-aggregated, and most-frequent in the upper-Town Creek sub-catchment; But also, near the centre of this gully-creekline invasion by Camphors is (see photo) the Town Creek itself, totally-lined with the characteristic bright-orange, slimy-gelatinous precipitate polluting the creek itself; immediately adjacent to mature Camphor laurels on both sides of the creekbank/s at this point.
Precipitate also observed in northern NSW
The orange precipitate is known scientifically as a rare sterol compound, believed to be the result of camphor oxidation in-water/soil water, and commonly & Individual Camphor trees of all-three age-class groups defined above are found to be most-aggregated, and most-frequent in the upper-Town Creek sub-catchment; But also, near the centre of this gully-creekline invasion by Camphors is (see photo) the Town Creek itself, totally-lined with the characteristic bright-orange, slimy-gelatinous precipitate polluting the creek itself; immediately adjacent to mature Camphor laurels on both sides of the creekbank/s at this point.
The orange precipitate is known scientifically as a rare sterol compound, believed to be the result of camphor oxidation in-water/soil water, and commonly & consistently observed in Northern Rivers creeks occurring within days of slowly flowing creeks and water-pondages being observed to be milky-opaque often for weeks beforehand e.g. tributaries of Terania Creek-Lismore (1999-2004).
(Reference: this sterol previously identified by a leading Melbourne chemical laboratory, in 2003, has as yet only a unique number in international Chemical Nomenclature).
Whereas most amateur and professional bird observers/ornithologists prefer to make most observations during daylight hours, it is known that certain bird species e.g. Swamphen, do most of their foraging-for-food at-night ; this may well be the reason, on Norfolk Island, that noone at-the-school, nor keen bird observers living there, and from-the-mainland have never recorded ANY BIRD consuming Camphor laurel fruits, or seeds.
The prior-published report/s of Cronin (1986) were reported to the islands leading Naturalist, Mr Owen Evans, who has spent a lifetime studying the natural history of Norfolk Island, that Currawong birds, Strepera graculina become behaviourally (seasonally) aggressive after consuming large volumes of Camphor laurel fruit in their diet from Sydney northwards in eastern New South Wales.
Norfolks most eminent Naturalist and one keen bird observer commenced observing territorial change/s in Swamphen population-dynamics during the summer of 2003-2004 ; Swamphen individuals were observed becoming aggressive, both in the lower reaches of the Town Creek catchment, as well as across-the-water on Phillip Island, some 3-4 kms from their breeding ground; population numbers had reached almost one hundred birds (Owen Evans, pers. comms), as compared to only a few around 1990. Historically, the birds never were known to fly to Phillip Island,or any other offshore islands of Norfolk; this was therefore a totally new occurrence, for which it is surmised, there could have been some or other chemical trigger; or was it purely population pressure due to overpopulation, that was forcing birds offshore?
Norfolk Islands professional Archaeologist, Helen Sampson is also an astute bird-observer. At the time of interview, on 12 August 2005, Helen stated that she had witnessed Kingston swampland-based Swamphen parent-birds both ambushing, and predating on, killing and eating young chickens of both commonly proliferating feral gamefowl, and hybrid-exotic duck species; also, that this aggressive activity had only commenced in the past eighteen months two year period.
A prima-facie connection was therefore established between the hypothesized vector of Camphor laurel fruits, the Swamphen, and their known individual-increased aggressiveness, on both the main island, and at Phillip Island ; this hypothesis is correlated to the known declining water quality status of Town Creek catchment areas; Town Creek runs northwards, and northeast towards the centre of the island, almost directly towards where the School Camphor trees exist; secondary invasions of garden Camphor trees, seedlings and suckers exist at the very-head of the Creeks catchment, in the vicinity of Little CuttersCorn.
Given all-the-evidence so far available, it is seen as highly desirable, and recommended that a limnological examination of the ecology of Town Creek be conducted by independent scientists, with a view to assessing:-
There clearly exists significant environmental deterioriation of Norfolk Island streams in the vicinity of the islands most historic watercourse, Town Creek,; at the same time, there
already exists, in-all-certainty, significant chemical,
perennial deterioration of the water quality of the same creek watercourse, the most historic of all Norfolk Islands catchments.
Both the availability of Camphor tree fruits, and the by-products effects of Camphor laurel fruits and seeds (ie their toxicity) help to explain why many native (NSW) bird species are seriously impacted, and now deteriorated in terms of both overall numbers and their geographic distribution.
Author: JOE A FRIEND
CRC- Camphor laurel Research Centre,
P O Box 1518, Lismore, NSW..2480