M.J. & A.R. Bamford CONSULTING ECOLOGISTS 23 Plover Way, Kingsley, WA, 6026 ph: 08 9309 3671 fx: 08 9409 2710 eml: [email protected] Rey Resources Duchess Paradise Project. Impacts associated with increased traffic; response to issues raised Dr M. J. Bamford 8th March 2012 BACKGROUND Rey Resources proposes to develop the Duchess Paradise Project in the Kimberley, about 120km south-east of Derby. This is a proposed coal mine and the project involves trucking coal from the mine, initially along an upgraded station road, and then along the existing Great Northern Highway and through to a port facility at Derby. One of the public comments concerns the impact of this road haulage as follows: “The proponent estimates there will be 60-80 trucks per day going from the mine to Derby. It can be expected that this traffic will have a significant impact on a range of species (e.g. many species of mammals, avifauna, frogs and reptiles) that inhabit roadside ecosystems in this region.” Rey Resources has asked Bamford Consulting to comment upon this concern. CONSIDERATION OF IMPACTS A number of factors need to be considered when assessing the likelihood that the traffic movements will result in significant impacts. These include: • Increase in traffic movements over existing levels. In this regard, important to note that the proposal consists of about 25km of an upgraded station road and about 140km along existing sealed highways which already carry commercial and private traffic. • Impacts are primarily through roadkill but roads can also be barriers, even for birds. This can be through the physical presence of an open, exposed area, but also through the movement of vehicles disturbing fauna. The station road will be widened from about 5m to 20m and will be fenced on both sides (currently fenced on only one side), and will be sealed. • The landscapes and therefore the fauna assemblages through which the route passes. While some roadkill is inevitable, significant roadkill is that which results in population declines that might affect population viability of species in the region. This is of particular concern for species of listed conservation significance. The effect of a road as a barrier will also be species-specific. • Time of day of haulage, as risk of roadkill can be expected to be greater around sunrise and sunset than at other times, and probably more at night than during the day. • Responses of fauna to traffic. There is an extensive literature on this. General points to consider are: o Some fauna species habituate to traffic, thus roadkill may initially be high but rates can be expected to decline. Significant impacts resulting in local population declines have been reported where new roads have been constructed through areas with high densities of wildlife, and roadkill as a cause of population decline has been documented for several medium-sized mammals in eastern Australia (Dufty 1989, Jones 2000). o Increased mortality due to roadkill is often more prevalent in habitats that have been fragmented ((Scheick & Jones 1999; Clevenger & Waltho 2000; Jackson & Griffin 2000). o Some fauna species are attracted to roads such as to feed on vegetation where runoff is concentrated, or to feed on roadkill. o Reptiles are more attracted to bitumen than gravel roads as they use the bitumen for thermoregulation in the late afternoon. High levels of roadkill have been observed on new bitumen roads (M.Bamford pers. obs.). The impact of this sort of mortality on reptile populations does not seem to have been investigated, but anecdotally reptiles seem to persist close to roads even with such ongoing mortality. This is probably because individual reptiles have small home ranges and the proportional loss to the population is low. In theory, such roadkill mortality of reptiles might affect populations in developed landscapes where the population is restricted to the road verge. • Impacts can be managed such as through underpasses, overpasses, fencing, signage, driver education and speed limits. • Species most vulnerable to roadkill are likely to be medium-sized mammals that occur in small populations that are thus sensitive to the loss of a few individuals, and lack the mobility to recruit from other areas to make up for local mortality. Large, terrestrial birds such as the Australian Bustard and Bush Stone-curlew can also be vulnerable to roadkill and in the case of the stone-curlew, birds may be sedentary and therefore local impacts may be significant. Birds attracted to drink at roadside pools (e.g. doves, finches) may be at risk and in some cases these include species of conservation significance (such impacts are discussed further below). On the basis of the above points, a number of conclusions with regard to impacts and road haulage associated with the Duchess Paradise Project can be drawn. • The upgraded station road (from the mine to the highway) is likely to be of greatest interest with respect to impacts, as this will be a wider, sealed road compared with the current station road. The increase in traffic will also be proportionally greater than on the highway. The station road crosses a branch of the Fitzroy River where there may be more fauna movements across the road than elsewhere. This is the sort of location where a new road could impact upon local populations of sensitive species (if sensitive species are present). • On the existing highway, the main change is the increase in numbers of heavy vehicles and this will be a proportional increase on current levels. The fauna on the highway is already habituated to vehicles and there is to be no increase in highway width. Existing rates of roadkill are probably low and would be expected to increase, at most, in proportion with the increased road movements. • The significance of impacts does depend upon the landscapes. Areas of interest may include narrow passes through rocky hills, watercourses and wetlands; all areas where wildlife may be abundant. There are few such features along the existing highway and roads (but there is a creek crossing along the existing station road), with the landscape consisting mostly of very widespread vegetation and soil types (based upon personal experience in the region and reports from Rey Resources). There is nothing to suggest that there are critical locations along the existing highway. • The significance of impacts also depends upon the fauna assemblage. Intensive fauna investigations have been undertaken by Rey Resources (Western Wildlife 2011) and have found that mammal species of conservation significance likely to be sensitive to roadkill, including the Northern Quoll, Bilby and West Kimberley Rock-Wallaby, are known from the area historically but are either locally extinct or do not occur along the road due to the lack of suitable habitat. Livestock grazing and altered fire regimes are believed responsible for the decline of these species. Some significant birds that may be sensitive to roadkill have been recorded, including Australian Bustard, Bush Stone-curlew, Star Finch and Pictorella Mannikin. Of these, the Bush Stone-curlew is of greatest concern as it is probably present in small numbers, associates with dense vegetation along watercourses and individuals may be sedentary; thus a local population can be vulnerable to the loss of just a few individuals. The two finches would only be vulnerable if flocks came to drink at roadside pools, resulting in large numbers of deaths. FURTHER INFORMATION AND INVESTIGATIONS The effects of roadkill are not included in Table 5-1 of the Environmental Scoping Document. Useful information that may already be available or could easily be gathered includes: • Information on roadkills along the highway; particularly any noted concentrations of roadkill. It is likely that there are no such concentrations but this needs to be checked. • Likewise, the possibility of critical locations along the existing highway and station road where fauna might be concentrated needs to be investigated. This could be based upon rapid assessment of habitats. CONCLUSIONS In general, there seems to be no reason to predict significant impacts upon fauna from increased traffic (haul trucks) along the existing highway. No change will be made to these roads, they already carry volumes of traffic and there appear to be few if any locations where fauna, particularly species of conservation significance, might concentrate and be vulnerable to increased traffic. Higher rates of roadkill can be anticipated, but anecdotal reports suggest existing rates are low. The situation may be slightly different with the upgraded station road between the mine and the highway. While a road is already present and carrying some traffic, the road will be wider, sealed and the proportional increase in traffic will be much greater than on the highway. There is also a crossing of a branch of the Fitzroy River that may be a sensitive location for fauna. There may be a peak in roadkill numbers initially, especially among reptiles attracted to the newly- sealed road to bask, but there are few species with populations likely to be sensitive to roadkill and at least some of this stretch of road passes through degraded landscapes (based on information provided by Rey Resources). It is also proposed to fence the road, which may reduce access by some species, while road design could avoid the formation of roadside pools that might attract wildlife. Monitoring of roadkill and driver education could assist in minimising the number of animal deaths. REFERENCES Clevenger, A. P. and Waltho, N. (2000). Factors Influencing the Effectiveness of Wildlife Underpasses in Banff National Park, Alberta, Canada. Conservation Biology 14 : 1-11 Dufty, A.C. (1989). Some Population characteristics of Perameles gunnii in Victoria. Wildlife Research : 18 (3) 355 – 365. Jackson, S. D. and Griffin, C. R.