______Assessment of risk to Large Forest on Lord Howe Isand from proposed wind turbines.

An assessment of the risk to the Large Forest Bat darlingtoni from proposed wind turbines on Lord Howe Island, New South Wales.

A report to Lord Howe Island Board

G.A. Hoye Fly By Night Bat Surveys Pty Ltd ABN 48 068 562 005

PO Box 271 BELMONT NSW 2280 Tel 4947 7794 Fax 4947 7537

January 2016

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1 INTRODUCTION

Fly By Night Bat Surveys PL was requested by the Lord Howe Island Board to assess potential impacts to the Large Forest Bat from two proposed wind turbines to be sited in pasture on the southern flank of Transit Hill. This species is currently the only native known to breed on the island. Previous survey has confirmed the presence of this species in the lower elevated parts of the island including the area where the two turbines are proposed (Fly By Night Bat Surveys 2010). A population of approximately 500 breeding females exists north of the airstrip, with a second smaller population centred around Mount Gower and Mount Lidgebird (Fly By Night Bat Surveys 2010-2014).

Significant mortality of microchiropteran has occurred at utility wind farms in North America and Europe (eg Kunz 2007b). In eastern North America mortality from turbine strike along forested ridge tops varies from 15.3 to 41.1 bats per megawatt (MW) of installed capacity per year Kunz (2007b). Lower rates have been reported from other parts of the US varying from 0.8 to 8.6 bats per MW per year. Higher mortality is associated with periods of migration of particular tree roosting bat species and may involve bats approaching turbines for inspection as potential roosts. (Kunz 2007a).

Two Vergnet GEV MP R 275 kW wind turbines are proposed for an area of pasture on the northern flank of Transit Hill, southwest of the current Powerhouse site. The turbines have two blades of 32 metres diameter set at a hub height of 55 metres (Jacobs Group 2015) and are able to be tilted for maintenance or other equirements. They will be guyed with cables to supporting masts. The turbines are rated for wind speeds of 12 metres per second and cut in at wind speeds of 3.5 metres per second and cut out at wind speeds in excess of 25 metres per second. Maximum rotor speed of 31 rpm would be achieved. The swept rotor area will occur between 39 metres and 71 metres above ground level at the turbine locations.

To assess the activity of the Large Forest Bat, echolocation calls were recorded at a wind monitoring mast sited immediately south of where the turbines will be located. Calls were recorded each night over a twelve month period at three heights to assess the relative activity of bats. Additional echolocation call detection was undertaken at locations within pasture, forest edge and within forest habitats adjacent to the proposed turbine locations during visits to the island in November 2014, and February, May, July and November of 2015 to assess the relative activity of the Large Forest Bat in pasture compared with forest habitats. Capture and banding of the Large Forest Bats was also undertaken during visits to the island to assist in providing population estimates and provide additional information on natural movements of individuals. It also provided information on the activity of the bats during the autumn and winter months, as previous survey had been restricted to spring and summer (Fly By Night Bat Surveys 2010-2014).

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2 SURVEY METHODOLOGY

To assess the risk to resident populations of the Large Forest Bat from blade strike and impact with guy wires and supporting masts, echolocation call detection was undertaken to quantify the activity of this species in the vicinity of the swept rotor range.

Effect of Habitat on Bat Activity

The degree to which bats utilise pasture in the vicinity of the turbines was assessed through the placement of Anabat SD1 and SD2 detectors within the adjacent forest, at the forest edge and in open pasture (refer to Figure 1 and Plates 1-3). Sampling was undertaken in November 2014, February 2015, May 2015, July 2015 and November 2015 (Table 1) to provide information of the use of these habitats throughout the year. The sensitivity of detectors was calibrated using a Bat Chirp Board (Nevada Bat Technology, Los Vegas USA) to ensure units were comparable. The detectors sampled throughout the entire night with files downloaded for subsequent analysis.

Figure 1 Sites sampled for echolocation calls to assess the effect of habitat on the activity of the Large Forest Bat.

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Plate 1 A detector placed in forest to the east of the turbines sites.

Plate 2 A detector placed at the forest edge to the east of the turbines sites.

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Plate 3 A detector placed in pasture near the wind monitoring mast.

Effect of Height on Bat Activity

The second area of investigation was the activity of the Large Forest Bat at three heights within pasture at the wind monitoring mast. Microphones were located at 2 metres, 20 metres and 40 metres height on a wind monitoring mast located in the clearing where the two turbines will be situated, and connected via cables to Anabat Express detectors near the base of the mast. The detectors were programmed to come on at dusk and record until sunrise. Sensitivity of the detectors was adjusted until all three were recording the same number of bat passes at ground level prior to placement of the microphones at the three heights. These ensured results were comparable between the detectors. The detectors were downloaded on visits to the island in February, May, July and November 2015.

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3 SURVEY RESULTS

Effect of habitat on Large Forest Bat activity

Activity of the Large Forest Bat was substantially higher within forest when compared to that in pasture for all of the surveys (refer to Graph 1). Activity levels within the forest were significantly higher than that in pasture during all four surveys (Kuskall Wallis non parametric test, H=6.60-15.98, 2 d.f., P<0.05). Activity levels in the forest were approximately an order of magnitude higher than that at the forest edge. There was generally an equivalent decrease in activity from the forest edge to that in pasture despite the detector being sited less than 30 metres into the pasture from the forest edge. This pattern was repeated during surveys undertaken in November 2014, February 2015 and May 2015. Activity between the three habitat types was not significantly different during the July 2015 survey, with low activity at forest, edge and pasture sites.

Graph 1 Activity of the Large Forest Bat within forest, at the forest edge and in open pasture.

These results indicate that the Large Forest Bat does not currently forage in or commute through the area of pasture to a substantial extent where the turbines are proposed to be sited.

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Effect of height on bat activity

Graph 2 The effect of detection height on activity levels of the Large Forest Bat at the mast.

Graph 2 displays the activity of the Large Forest Bat at the mast at 2 metres, 20metres and 40 metres height. While activity was low even at 2 metres, activity at 20 metres height was negligible. This suggests that the small number of bats passing over the pasture do so close to ground level. No activity was present at 40 metres height, indicating that the likelihood of the Large Forest Bat passing through the swept rotor area of the proposed turbines is low.

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Temporal variation in Large Forest Bat activity in the vicinity of the mast

Graph 3 Nightly variation in activity of the Large Forest Bat at ground level at the mast.

As seen in Graph 3, activity of the Large Forest Bat at ground level at the mast varied from no or little activity on some nights to over 50 passes per night on a few occasions. While activity fluctuated from November until April, activity declined dramatically from the end of March with little to no activity in winter. Activity is presumed to have increased again sometime between September and November 2015, but faults with the microphones of the detectors in late September resulted in no data being recorded for this period

Activity of the Large Forest Bat at 20 metres height at the mast was substantially less than that at ground level (refer to Graph 4). Activity was recorded on far fewer nights than at ground level and echolocation call passes rarely peaked over 10 passes per night. Most activity was recorded during December 2014 with no call passes being recorded at this height after early January. No echolocation call passes were recorded at 40 metres height at the mast.

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Graph 4 Nightly variation in activity of the Large Forest Bat at 20 metres height at the mast.

Mean nightly activity levels at the three detector heights at the mast are shown in Graph 5. While activity of the Large Forest Bat was low, even at ground level in the vicinity of the mast during the summer months from November to March, even lower activity was recorded from April until September. This indicates that the probability of blade strike is even lower during the winter. It should be noted that the detector at ground level ceased functioning in September 2015 and activity from then until early November was not recorded. It is likely however that activity of the Large Forest Bat begins to increase from winter lows sometime in late September or early October.

Graph 5 Activity levels of the Large Forest Bat at the mast at the three heights sampled.

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Graph 6 Mean nightly activity of the Large Forest Bat at ground level at the mast site.

The pattern of activity of nightly activity of the Large forest Bat at ground level at the mast for the period between November 2014 and February 2015 is displayed in Graph 6. While some variation in activity was present throughout the night from dusk, a distinct peak was present at dawn. Mean activity was however very low with this peak representing just over one echolocation call pass per 15 minute period.

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4 DISCUSSION & RECOMMENDATIONS

While significant mortality of microbats from blade strike of wind turbines has been recorded in both Europe and North America (Erickson et al, 2004, Hayes 2013), the position in Australia is less clear. By the end of 2014, 1866 turbines had been installed across 71 sites across southern Australia (Clean Energy Council 2015). Few reports are publicly available on mortality of microbats at these sites. At two wind farms in Tasmania, Gould’s Wattled Bats gouldii accounted for the majority of carcasses found during searches, with almost all adult males or females in approximately equal proportions (Hull & Cawthen 2014). Most of the fatalities at these sites occurred during autumn. Two of the carcasses however were Vespadelus species with one at least most likely Vespadelus darlingtoni, the microbat currently extant on Lord Howe Island.

It is currently uncertain whether mortality occurs chiefly as a result of direct blade strike or is the result of barotrauma due to increased pressure close to blades (Ellison 2012). Earlier investigations suggested barotrauma to the lungs and possibly other organs accounted for 46% of bats killed at turbines with 92% of bats having haemorrhaging in the thoracic and/or abdominal cavities (Baerwald 2008). Later studies cast some doubt on the level of deaths from barotrauma and the degree to which this contributes to turbine related deaths is currently uncertain (Grodsky et al 2011; Rollins et al 2012). The majority of bat fatalities in North America are believed to be of migrating bats in autumn (Ellison 2012). The main species involved are tree roosting, relatively large species that are known to forage widely in open spaces. It is possible that they are examining turbines as potential roost sites or for social interactions with other individuals (Horn et al 2012; Jameson & Willis 2014). Bats have been found to be more active around turbines at lower wind speeds and often approach turbines from downwind (Cryan et al 2014). Barclay et al (2007) found that the number fatalities of bats increased exponentially with tower height in contrast to nocturnal birds. This may be due to bats migrating at lower elevations than nocturnal birds. In a survey at two wind farms in northwest Portugal, Amorim et al (2012) found that most mortality occurred during autumn. Both bat activity and mortality were significantly correlated with wind speed, temperature and relative humidity.

The Large Forest Bat appears to form two largely separate sub populations on Lord Howe Island, one centred around the settled area of the northern part of the island and the other around the southern mountains. No movement of banded bats between the two areas has been recorded since banding commenced in 2010. In the more studied ―northern‖ population, considerable movement of individuals has been recorded between trapping sites (Hoye, unpublished). In females, the maximum movement between capture sites recorded is 1332 metres with over 75% of movements less than 500 metres (Hoye 2012). Movements of males was even less.

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Targeted survey was undertaken over twelve months from November 2014 until November 2015 to assess use of the proposed turbine sites. Activity levels in the pasture in the vicinity of where the turbines are proposed were very low when compared with that within adjacent forest. Within pasture activity of the Large Forest Bat was highest near ground level and was an order of magnitude lower at 20 metres height. No activity was recorded at 40 metres height which equates with the bottom of the swept rotor area of the proposed turbines. Activity was also highly seasonal with peak activity between October and March. These results suggest that the turbines pose a low probability of blade strike to the Large Forest Bat from random interactions. The support masts and guy wires will be situated closer to the forest edge where activity of the Large Forest Bat is higher. The risk of collision with these structures may be higher. No evidence of mortality form collision with the guy wires and wind wind monitoring mast was gathered during visits to the island from November 2014 until November 2015. The small size of the Large Forest Bat (~4-7 grams) and the relatively high pasture present in the vicinity of the wind monitoring mast would have resulted in a l ow probability of seeing carcases during these visits.

While there would appear to be a low probability of blade strike due to random collisions, this may not be the case if Large Forest bats are attracted to the turbines for roost inspection or other reasons. Jameson & Willis (2014) found that microbats were attracted to large structures. While there has been low activity recorded in the vicinity of the wind monitoring mast installed in November 2014, this may or may not be the case for the turbines. Some monitoring is justified when the turbines are first commissioned. Some echolocation call detection around the turbines when they are first installed would indicate if they attract bats. A search of the ground below the turbines and associated guy wires ans support masts for carcasses should also be carried out seasonally for the first year following their commission. The small size of microbats can result in removal of carcasses by predators. Introduced Black Rats (Rattus rattus) as well as two native birds, the Lord Howe Currawong (Strepera graculina crissalis) and Australian Kestrel (Falco cenchroides) are likely predators of bat carcasses around the proposed turbines. The long grass where the turbines are proposed to be sited may hamper carcass searches. The use of a sniffer dog may assist in finding dead bats in this area. The use of trained dogs has been found to at least double the number of carcasses found during searches around turbines (Ellison 2012). The feasibility of using sniffer dogs should be evaluated. Keeping the grass cropped low in thevicinity of the turbines would also assist in finding carcasses. Currently, the Large Forest Bat is monitored partly through capture and marking (Fly By Night Bat Surveys PL (2011-2014). This would appear to be the most efficient method for monitoring the persistence of the Large Forest Bat in the northern section of the island against a range of possible impacts including rat predation, proposed rat control and climate change. Mortality from the wind turbines is unlikely to be sufficient to be detected from the marking program. The installation of permanent monitoring site on the island whereby echolocation calls are constantly recorded and analysed would provide an additional method of assessing the relative abundance of the Large Forest Bat on an ongoing basis. This is feasible using similar equipment as that used to monitor call activity at the mast. It would provide a cost effective means of monitoring the presence of the Large Forest Bat and would also indicate if vagrant microbat species reach the island.

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Glenn Hoye

January 2016

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5 REFERENCES

Amorim, F., Rebelo, H. & Rodrigues, L. (2012) Factors Influencing Bat Activity and Mortality at a Wind Farm in the Mediterranean Region. Acta Chiropterologica 14:2, 439-457. Baerwald, E.F. (2008) Variation in the activity and fatality of migratory bats at wind-energy facilities in southern Alberta—Causes and consequences: Calgary, Alberta, Canada, University of Calgary, Unpublished Master’s Thesis. 125 pp. Barclay, R. M R., E. F. Baerwald, and J. C. Gruver (2007) Variation in bat and bird fatalities at wind energy facilities: assessing the effects of rotor size and tower height. Canadian Journal of Zoology 85:381–387. Clean Energy Council (2015) Wind Energy, accessed 23 December 2015, https://www.cleanenergycouncil.org.au/technologies/wind-energy.html Collins, J. & Jones, G. (2009) Differences in Bat Activity in Relation to Bat Detector Height: Implications for Bat Surveys at Proposed Windfarm Sites. Acta Chiropterologica 11:2, 343-350. Cryan, P. M., P. M. Gorresen, C. D. Hein, M. R. Schirmacher, R. H. Diehl, M. M. Huso, D. T. S. Hayman, P. D. Fricker, F. J. Bonaccorso, D. H. Johnson, K. Heist, and D. C. Dalton (2014) Behavior of bats at wind turbines. PNAS. 111: 15126-15131 Ellison, L.E. (2012) Bats and wind energy—A literature synthesis and annotated bibliography: U.S. Geological Survey Open-File Report 2012–1110, 57 p. Parsons, S. & Phil Battley, P. (2013) Impacts of wind energy developments on wildlife: a southern hemisphere perspective. New Zealand Journal of Zoology 40, 1-4. Erickson, W., G. Johnson, D. Young, D. Strickland, R. Good, M. Bourassa, K. Bay, and K. Dürr, T. and L. Bach (2004) Bat deaths and wind turbines–a review of current knowledge, and of the information available in the database for Germany. Bremer Beiträge für Naturkunde und Naturschutz 7:253–264. [In German.]. Erickson, J. L. and S. D. West. (2002) The influence of regional climate and nightly weather conditions on activity patterns of insectivorous bats. Acta Chiropterologica 4:17–24. BioOne Grodsky, S.M., Jennelle, C.S., Drake, D., Virzi, T. (2012) Bat mortality at a wind-energy facility in southeastern Wisconsin. Wildlife Society Bulletin 36, 773-783. Fly By Night Bat Surveys PL (2014) Results of microbat survey Lord Howe Island December 2013. Report to Lord Howe Island Board. January 2014. Fly By Night Bat Surveys PL (2013) Results of microbat survey Lord Howe Island 2013. Report to Lord Howe Island Board. June 2013. Fly By Night Bat Surveys PL (2012) Survey of the Microbat Fauna of Lord Howe Island during December 2011/January 2012. Report to Lord Howe Island Board. June 2012. Fly By Night Bat Surveys PL (2011) Survey of the Microbat Fauna of Lord Howe Island during November 2010. Report to Lord Howe Island Board. January 2011. Lord Howe Island Board (2009) Draft Rodent Eradication Plan. Draft Lord Howe Island Rodent Eradication Plan, Lord Howe Island Board, Lord Howe Island. Oct 2009. Grodsky. S.M., Behr M.J., Gendler A., Drake D., Dieterle B.D., Rudd R.J. & Walrath N.L. (2011) Investigating the causes of death for wind turbine-associated bat fatalities. Journal of Mammalogy 92: 917 925. Hall, L. S. and G. C. Richards. (1972) Notes on Tadarida australis (Chiroptera: Molossidae). Australian Mammalogy 1:46. Hayes, M. A. (2013) Bats killed in large numbers at United States wind energy facilities. BioScience, 63:975–979. Horn, J., E. B. Arnett, and T. H. Kunz. (2008) Interactions of bats with wind turbines based on thermal infrared imaging. Journal of Wildlife Management 72:123–132. BioOne Hoye, G.A. (2012) Recent survey of microbats on Lord Howe Island, southwest Pacific. Spoken Presentation. 15th Australasian Bat Conference. Melbourne, Australia. April 2012.

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Hull, C.L. and L Cawthen, L. (2013) Bat fatalities at two wind farms in Tasmania, Australia: bat characteristics, and spatial and temporal patterns. New Zealand Journal of Zoology 40, 5-15. Jacobs Group (2015) Lord Howe Island Renewable Energy Project - Wind Turbine Generator Noise Impact Assessment, Revision 4. A report to Lord Howe Island Board. April 2015. Jameson, J. W. and Willis C.K.R. (2014) Activity of tree bats at anthropogenic tall structures: implications for mortality of bats at wind turbines. Behaviour. 97:145–152. Kunz, T. H., E. B. Arnett, B. M. Cooper, W. P. Erickson, R. P. Larkin, T. Mabee, M. L. Morrison, M. D. Strickland, and J. M. Szewczak (2007a) Assessing impacts of wind- energy development on nocturnally active birds and bats: a guidance document. Journal of Wildlife Management, 71:2449–2486. Kunz, T. H., E. B. Arnett, W. P. Erickson, A. R. Hoar, G. D. Johnson, R. P. Larkin, M. D. Strickland, R. W. Thresher, and M. D. Tuttle (2007b) Ecological impacts of wind energy development on bats: questions, research needs, and hypotheses. Frontiers in Ecology and the Environment, 5:315–324. Rollins K.E., Meyerholz D.K., Johnson G.D., Capparella A.P. & Loew S.S. (2012) A forensic investigation into the etiology of bat mortality at a wind farm: barotrauma or traumatic injury? Veterinary Pathology 49: 362 371. Rydell, J., Bach, L., Dubourg-Savage, M.,Green, M. ,Rodrigues, L. & Hedenström, A. (2010) Bat Mortality at Wind Turbines in Northwestern Europe. Acta Chiropterologica 12:2, 261-274. Jens Rydell, Lothar Bach, Marie-Jo Dubourg-Savage, Martin Green, Luísa Rodrigues, Anders Hedenström. (2010) Mortality of bats at wind turbines links to nocturnal insect migration?. European Journal of Wildlife Research 56, 823-827. Tidemann, C.R. and Woodside, D.P. (1978) A collapsible bat trap and comparison of results obtained with the trap and with mist-nets. Australian Wildlife Research 5:355-362. Weller, T.J. and Baldwin J.A. (2012) Using echolocation monitoring to model bat occupancy and inform mitigations at wind energy facilities. The Journal of Wildlife Management, Wolbert, S.J., Zellner, A.S. , and Whidden, H.P. (2014) Bat Activity, Insect Biomass, and Temperature Along an Elevational Gradient. Northeastern Naturalist 21:1, 72-85. Staton, T. and Poulton, S. (2012) Seasonal Variation in Bat Activity in Relation to Detector Height: A Case Study. Acta Chiropterologica 14:2, 401-408.

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