1.1 The Problem The incidence of native animals killed due to collisions with vehicles is comparatively high in Tasmania. There have been 37 road kills of devils recorded at Woolnorth in 2010 and 2011 (unpublished data DTDP 2012). The main contributors to collision anywhere are the speed of vehicles, the visibility of animals and the lack of opportunity for animals to escape. The time of highest risk tends to be between dusk and dawn. In Tasmania a number of animals are predators and scavengers and these include the tasmanian devil, the spotted-tailed quoll and the wedge-tailed eagle. When these animals are attracted to, and scavenging on, the carcass of other species they are at even higher risk because they are on the road for an extended period. In the case of tasmanian devils a carcass may attract more than one animal and so increases the risk of multiple roadkills. Of particularly risk to the tasmanian devil, is the potential to spread DFTD from one animal to another at roadkill sites when they are “fighting” over the carcass. So, an increase in scavenging due to the presence of road kill could conceivable increase the rate of spread from one animal to another in places where the disease is already present. Woolnorth is free of DFTD so this risk does not exist. The absence of DFTD makes the Woolnorth population of devils very important; as such every effort will be made to reduce the impact of roadkill on the population. At Woolnorth, the development of dairies will include an increase in the number of vehicles using the roads. With this increase come the risk of an increase in the number of road kill. The increase will come from the increases in the number of permanent residents on the dairy farms, agricultural vehicles and milk trucks. Other existing road users are unlikely to increase as a result of the Action. These include other local residents from the vicinity, tourism and vehicles associated with the adjacent wind farm. At certain times of year an increase on traffic around or before dawn and around or after dusk may be experienced when operating the farms. Consequently, it is necessary to ensure that the possibility of increasing the number of roadkills with the attendant potential impact on MNES is mitigated. 1.2 Previous work A detailed assessment of the roadkill issue was undertaken as part of the PER for the Tarkine Road proposal (Pitt and Sherry 2012 and co authored by North Barker). That assessment included the convening of an expert panel to bring together the accumulated knowledge of the participants and focus on the issue. The panel consisted of Tasmanian scientists and professionals with recent and relevant expertise and experience in roadkill, vertebrate carnivores and DFTD, a veterinarian, and State and Federal Government regulators. That subsequent investigation included research that tested the methods applied to the problem as well a the effectiveness of various mitigation efforts. This proposal draws from that experience and adopts the methods that have been demonstrated to be effective. 1 1.2.1 Measuring roadkill at Woolnorth To better understand the incidence of roadkill along the Woolnorth and Harcus River roads, a basis for designing mitigation options was devised. The basis involves: • Roadkill baseline establishment • Live animal baseline establishment • Traffic counts • Analysis of the results • Roadkill mitigation • Roadkill, live animal and traffic monitoring • Adaptive adjustment of mitigation Roadkill baseline establishment Some existing data from Woolnorth were not collected systematically and so, while indicative of a substantial pre existing issue, are otherwise not useful to this study. Systematic roadkill surveys are essential in determining the frequency of roadkill, and to identify hotspots. It is also necessary to obtain high quality spatial and temporal data on live animal abundance to assist in development of the mitigation strategy. In November 2012, a 12 month study of the abundance of medium to large mammals on the road began, both as live animals and roadkill. The aim of the study is to collect baseline data needed to inform potential mitigation options. The study is designed to record the species, location and frequency of roadkill, describe the spatial and temporal patterns of roadkill distribution, identify when, where and at what scale roadkill hotspots occurred, and to inform development of effective roadkill mitigation. Only animals seen by the driver of a vehicle were noted (i.e. small animals may not have been recorded). The following work was undertaken: 1. Roadkill monitoring • Study area: The Woolnorth Road passing through the Woolnorth property – and the Harcus River Road along the south eastern boundary of Woolnorth (Figure **). • Roadkill monitoring will be undertaken daily for 3 x 3 week periods during January 2013, March 2013 and June 2013. • Data recorded: the GPS location of the roadkill, the species and any evidence of scavenging on the carcasses, vegetation type and structure, width of cleared road reserve. (see Appendix 1 for additional data to be collected in support of the Save the Devil Program) • After the roadkill are recorded, the carcasses should not be moved. This will ensure that the monitoring program does not skew the roadkill data by altering the behaviour and visitation of scavengers, young at foot and other conspecifics investigating a carcass. 2. Live animal headlight survey Under normal circumstances a pre Action baseline would be the basis for determining if an increase in roadkill is detected. However, in this case, the Action involves the clearance of 1850 ha of habitat. This clearance may result in the displacement of animals or a change in animal behaviour. A reduction in the number of live animals 2 could reduce the number of local roadkill. Such a reduction could mask the impact of an increase in traffic. • The aim of the live animal survey is to provide abundance data on animals to compare with the roadkill observations and potentially predict additional hotspots. • The second aim is to provide a covariate for any change in the incidence of roadkill during the operation phase following land clearance and any increase in traffic. • The live animal survey is via windscreen observation under headlights and will be conducted over a period of three weeks at three different times during the year (January 2013, March 2013 and June 2013.) • The data recorded: GPS location, in or out of road reserve and species, vegetation type and structure, width of cleared road reserve. • Surveys will be undertaken daily, commencing at approximately 30 mins after sunset. • The live animal surveys will be conducted at a speed of 50-60 km/h. 3. Traffic counts The measurement of existing traffic flows and speed to provide baseline data is needed. The sites for traffic counts were identified at nodes at which traffic flow is likely to change, ie up stream of main intersections and at the entrance to the property (Figure **). Because of the low and potentially variable traffic flows, the traffic counters will be left in place for one month. Traffic counts will be undertaken in January 2013, March 2013 and June 2013 to capture the seasonal variation of tourism and some agricultural activities in the study area. These periods correspond with the roadkill monitoring and headlight surveys. Analysis A statistical analysis of the data will be undertaken. The objectives of the analysis are to: • Identify spatial, seasonal and other patterns in activity and roadkill levels • Identify areas of high live animal activity and roadkill hotspots • Correlate live animal activity and vegetation variables with roadkill • Identify areas of high roadkill risk • Predict how roadkill numbers will change following land clearance and road traffic increases. • Compare post construction and mitigation roadkill with the prediction do determine the effectiveness of mitigation actions. Following the construction phase, it is proposed that an ongoing strategy to assess and address any increase in roadkill as a result of the project. This proposed strategy will continue to use an adaptive management framework to monitor, evaluate and mitigate the potential impact to MNES from roadkill. This staged approach to risk management is designed to allow potential changes to be flagged through an ongoing, informal monitoring strategy. This allows for changes to be identified and investigated quickly so that appropriate mitigation strategies can be employed. 3 Pre-construction monitoring and analysis of roadkill patterns provides information on baseline levels of roadkill for different road sections. This information will be used to set expected roadkill carcass detection rates both for a given section over a given time period and for individual passes. These expected counts will be adjusted for impacts of land clearance on live animal numbers and then will provide trigger levels. If triggers are exceeded immediate investigation and a management response will follow. The data sourced for the analysis is summarised in Table Error! No text of specified style in document..1. Table Error! No text of specified style in document..1 - Summary of data source for the baseline roadkill analysis Data Coverage: Live animal survey Roadkill survey Traffic data 3x daily observations (21days) Weekly surveys Oct 2009 – Sept 2010 (no July) Hourly Observations, concurrent with Live animal survey. Oct 2009, Jan 2010, Apr 2010 Also 3 x 28 daily observations over the same periods as the live animal surveys. Hourly traffic count and average speed. Surveys carried out in evening Environmental (predictors) data Road slope data Vegetation Data Road curvature Road segment Surveys carried out in early morning 1.3 Mitigating roadkill at Woolnorth The distribution of roadkill occurs at fine spatial scales, allowing the human and natural factors to be manipulated at this scale to reduce roadkill (Hobday & Minstrell 2008). However, the suitability of any mitigation measure depends on local road conditions and species interactions with the road environment, species behaviour and ecology, and with the density of animals in surrounding habitat (Magnus 2006). There are two main types of roadkill mitigation measures: changing driver behaviour and changing wildlife behaviour (Clevenger et al 2003, Coffin 2007, Magnus et al 2004). Changing driver behaviour includes changing driver attitude by increasing driver awareness, increasing awareness of roadkill hotspots and slowing speed. Potential ways to alter wildlife behaviour include discouraging wildlife from grazing on roadsides, preventing wildlife from crossing roads or providing safe crossings where prevention is not possible (Magnus et al 2004). Changing or controlling animal behaviour is more problematic. For example, fencing to prevent animals from crossing the road can itself have negative impacts by trapping animals that breach a fence on the roadside and preventing connectivity between habitat patches. Changing the potential for collision is the best approach. A reduction in the vehicle speed from 100 km/h to 80 km/h was found by Hobday & Minstrell (2008) to potentially decrease overall roadkill by up to 50%. Reduced vehicle speed gives drivers and animals greater time to do ‘risk assessment’ and avoid collision. 4 Improving visibility along and alongside roads is another method of giving animals and drivers a greater opportunity to avoid collision (Hobday & Minstrell 2008). This can be achieved through vegetation removal. Improving visibility might also mean some species are less secure and flush earlier, providing more time for escape and avoidance. Magnus et al (2004) and Magnus (2006) assessed a range of other roadkill mitigation measures for their utility in reducing wildlife roadkill in Tasmania. The following measures, and potentially relevant to the Action, were identified as being likely to reduce wildlife roadkill: vegetation management, escape routes, table drain management, wildlife signs, chicanes and speed humps. Magnus et al (2004) and Magnus (2006) highly recommend the provision of escape routes and consider them as one of the most useful and imperative measures that can be implemented when roads are being upgraded, widened or sealed. Table drain management to reduce roadside resources, such as roadside vegetation and water pooling in drains was also highly recommended. The effectiveness of signs to significantly reduce vehicle speed or collision rate is uncertain (Jones 2000, Magnus et al 2004, Magnus 2006, Thompson 2011). Although light coloured pavement is suggested to potentially decrease roadkill, due to increased visibility, it is not a practical retrofit solution. Mitigation actions: Remove road kill from all roads within Woolnorth. Limit vehicle road speeds to 80 km hr Increase sight line and roadside visibility Clear vegetation from roadsides from fence to fence Maintain short roadside grass o Additional potential actions in response to triggers Install rumble strips on approaches to hotspots on Woolnorth Road Animal proof fencing and road grids adjacent to hotspots Increased control of wallaby Strategically located carcass’s for scavenging 5 Appendix 1. Parks and Wildlife Service Road kill Report Sheet TASMANIAN DEVIL ROADKILL REPORT 1. DID YOU STOP TO CHECK THE DEVIL? section 2 of this form NO YES this form please complete please complete all 2. GENERAL INFORMATION NAME OF RECORDER: PWS OFFICE/ORGANISATION: DATE OF OBSERVATION: LOCATION OF THE DEVIL: please provide road name or number, and devil location relative to a prominent landmark; provide easting/northing if possible WHAT IS THE SPEED LIMIT OF THE SECTION OF ROAD ON WHICH THE DEVIL WAS FOUND ? KM/H 3. IDENTIFICATION WAS THE DEVIL SCANNED FOR A MICROCHIP? NO YES microchip present microchip number: no microchip present r-number: WAS A BIOPSY TAKEN? YES NO HAVE YOU SENT US PHOTOS OF THE DEVIL? YES NO Please ensure the r-number or microchip number is attached or quoted on any biopsy vials / photos sent to us 4. OTHER ROADKILL WAS THERE ANY OTHER ROADKILL WITHIN 50M OF THE DEVIL? NO YES wallaby or similar other marsupial bird reptile / amphibian unknown 5. DEVIL DETAILS WHAT WAS THE AGE OF THE DEVIL? WHAT WAS THE GENDER OF THE DEVIL? Juvenile (cat-sized, with no old scars) Male Adult (more than 4kg, with some scars) Female Unknown Unknown WHAT WAS THE STATUS OF THE DEVIL’S POUCH? Unknown Empty, small teats Lactating (swollen teats) Number of active teats Number of pouch young Approximate length of young mm 6. DISEASE STATUS DID YOU CHECK FOR DFTD? NO YES please describe any symptoms you saw, or put n/a if no symptoms were seen. 7. ANY OTHER INFORMATION IS THERE ANY OTHER INFORMATION YOU WOULD LIKE TO GIVE US? THANKS FOR YOUR TIME! 6
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