Extent of harm on the habitat of the Eastern Chestnut Mouse
103 Although Mr Robertson did not appear on behalf of Mr Freeman at the hearing on the plea of not guilty, I reminded him that Mr Freeman conceded that the road works harmed the habitat of the Eastern Chestnut Mouse and Grass Owl. Therefore, the only argument open to him relates to the extent of harm to the habitat and the extent of harm to the actual species themselves.
104 As noted in Garrett v Freeman (No. 4) at [72], Mr Redpath, a regional ecologist at the Grafton Office of the DIPNR, conducted a target fauna survey in the Partridge Creek area in December 2002 to evaluate the ERM report. On that occasion he observed a "thriving breeding population" of the Eastern Chestnut Mouse.
105 One such place where the mouse was found, labelled as PCS-007, was located to the east of the creek. This location was some 125 metres from the east-west road and Mr Robertson submits that for this road to have crossed the Eastern Chestnut Mouse core habitat, the mouse would have to have had a range well in excess of three hectares. On this basis, he argues that there is no possible way that the presence of the species at that location could prove that the road interfered with any part of its habitat, the mouse only having a range of half of a hectare according to Mr Redpath.
106 Another location at which the species was detected is on the eastern side of the creek, labelled as PCS-003. Since no part of the roads does bridge the creek, Mr Robertson argues that it is impossible to say that the habitat of the species was damaged by the north-south road, it being highly unlikely that the mouse can traverse creeks.
107 In December 2005, Mr Redpath undertook another survey of the area as part of the post works monitoring of the ASSR project and revisited his sample sites. No Eastern Chestnut Mouse, despite an extensive amount of trapping effort, was captured or observed. Mr Redpath states:
Comparison of site photographs does clearly demonstrate the biomass of vegetation at the three original sites has increased significantly between the first and second surveys. Of all the considerations, the increase in biomass resulting from higher water levels and recent flooding is the most likely factor influencing the presence/absence of ECM [Eastern Chestnut Mouse] in the study area.
108 Mr Redpath lists a number of land management activities and perturbations which could have the most potential to influence the presence or absence of the target species. Those factors relevantly include the construction of a weir to regulate water level and construction of an access road through the area. He notes that the wildfire in November 2002 coupled with significant rainfall in April, June and July 2005 possibly had a significant impact on the species. In particular, the conditions that exist after a wildfire are likely to favour another species, Rattus Lutreoulus or the Swamp Rat, over the Eastern Chestnut Mouse.
109 It follows that although there was a decline in the actual number of species detected in 2005, after the construction of the roads, this could be attributable to other factors cumulatively with the construction of the roads.
110 Mr Redpath notes that, prior to the construction of the roads, the wetland acted as a potential barrier to access for predators. Mr Redpath recommends a number of measures until the precise reasons for the absence of the species are established - the removal of the road being one of these measures.
111 Professor Fox, who is put forward as the world's foremost expert on the Eastern Chestnut Mouse, opines that the failure to obtain a record of the species in the 2005 Redpath's survey provides a strong inference that there had been substantial damage to the population from the road construction.
112 Despite the impact of the wildfire and subsequent rising water levels, Professor Fox maintains that the roads had the greatest impact. He reasons that the species is able to cope with fire and fluctuating water levels and is most affected not by fire, but by predators which emerge after fire.
113 Mr Robertson relies upon the report of HWR Ecological titled "Thrumster Sand Plain Sewerage Treatment Plant - Ecological Assessment" ("the HWR report") dated 30 August 2005, which was carried out by Mr John-Paul King. It can be observed that, although this report is somewhat disorganised, it states that both the Grass Owl and the Eastern Chestnut Mouse were located in the Partridge Creek area after the roads had been constructed.
114 The prosecutor argues that the HWR report is deficient in a number of respects, namely; (i) the report contains no point-sourced data on the location of the reported capture; (ii) there is nothing in the report to say that what was captured was an Eastern Chestnut Mouse; (iii) the report lacked the sort of trapping and geographic information to repeat the survey; and (iv) the report says nothing about who conducted the trapping, their expertise or qualifications.
115 The prosecutor's view is supported by Professor Fox, who opines that the HWR report lacks the very strong confirmatory evidence that would be required for this species. He also points out that in December 2005, 640 trapping nights were undertaken at Partridge Creek, which was six to seven times more than the trapping effort in the HWR report, and in which no Eastern Chestnut Mouse was found.
116 I accept the prosecutor's submission that, for the reasons stated in par [114] above, this report cannot be reliably used to maintain a conclusion that the roads had little or no impact on the Eastern Chestnut Mouse. I also accept the opinion of Professor Fox, noted in par [115] above, which I find persuasive.
117 Mr Robertson also relies upon the ERM report which was prepared for the council in October 2002 prior to the proposed construction of an embankment at Partridge Creek to inundate the acid sulphate soil layers with surface and groundwater inflows. The ERM report states that the proposed activity is considered likely to have a significant impact and that large proportions of known and potential habitat is likely to be removed or significantly modified by the proposed extent of inundation.
118 The ERM report describes in detail the components of habitat that the species needs to survive. The Eastern Chestnut Mouse feeds on plant stems, seeds, fungi and insects, and it has a home range of less than half a hectare.
119 The species was recorded in dense sedge land habitat approximately 400 metres south of the proposed embankment location where the sedgeland consists of a common rush couch grass sedgeland vegetation community, which covers approximately 32.43 hectares. The Eastern Chestnut Mouse was not recorded at any other sedgeland habitats in the survey area. The report, however, states that the species may still occur in other areas of sedgeland habitat at lower densities. The then proposed strategy was expected to inundate approximately 54.48 per cent of the closed sedgeland habitat which includes 87 per cent sedgeland vegetation community. This represents a large proportion of known habitat and for that reason significant impact on the habitat of the Eastern Chestnut Mouse was predicted.
120 Mr Robertson also relies on the evidence of Mr Milledge. In his 2007 report, Mr Milledge states that since the wildfire at November 2002, no records of the species have been made in the area. Mr Milledge notes, however, that there is no evidence that re-colonisation of the species did in fact occur after the wildfire because there were no surveys conducted until 33 months after the fire. He also cites the competitive presence of the Swamp Rat and the possibility that the survey effort was insufficient to detect remaining individuals, as possible explanations for the absence of the species. In his opinion, the absence of the species in 2005 and 2007 is not necessarily attributable to the construction of the roads.
121 Mr Robertson notes that Mr Milledge attempted to replicate Mr Redpath's survey in 2008 and was unable to do so at sites PCS-003 and PCS-007 due to heavy inundation as a result of the ASSR project. Mr Milledge did, however, capture two female species 300 metres south west of the site where Mr King captured the species in 2004. At this site, he noted a lower density of the competitor, the Swamp Rat, as opposed to the other three sites where the Swamp Rat contributed 76 per cent of captures and a high incidence of re-captures. In his opinion such a high presence of the Swamp Rat possibly accounts for the low incidence of the Eastern Chestnut Mouse.
122 Ms Stewart and Ms McKenley, both qualified and highly experienced ecologists, co-authored a report dated November 2007. The report attempts to evaluate regeneration of vegetation in relation to habitat requirements of the relevant threatened species. The report states that all regeneration observed along excavated road sections is in the early stages and nowhere approached the height of mature vegetation. The report notes an absence of the elements of the habitat favourable to the presence of the Eastern Chestnut Mouse such as low, dense vegetation for shelter, foraging and breeding.
123 Mr Robertson acknowledges that the north-south road traversed the type of vegetation associated with the species. He submits, however, there is no evidence that the species ever used that area.
124 The evidence clearly shows, however, that the Eastern Chestnut Mouse can occur in the vegetation type that has been disturbed by the construction of the roads. Moreover, the nature of roads, devoid from vegetation, can function as a substantial disincentive for the species to travel within the parameters of suitable habitat.