Waihi North Project: Assessment of Terrestrial Ecological Values & Effects 62138 WNP AEE 19 Long tailed bats are classified as ‘Nationally Critical’ in the North Island (O’Donnell et al., 2018) and are threatened by habitat loss, fragmentation and introduced predators. Because the species is often difficult to observe in the wild, the paucity of records around the Waihi area may only reflect a lack of survey effort. Long-tailed bats require large trees (including exotic and standing dead trees) with cavities (e.g. deep knot holes), epiphytes and loose bark for roosting; and typically use linear landscape features such as bush edges, gullies and water courses to transit between roosting and feeding sites (Borkin and Parsons 2009; Griffiths 1996). These bats tend to forage in open areas, including clearings (Borkin and Parsons 2009; Griffiths 1996), along forest edges (Alexander 2001; O’Donnell and Sedgeley 1994), over wetlands, open water and along rivers and roadways (Borkin and Parsons 2009; Griffiths 1996). 3.3.4.1 Automatic bat monitoring detectors ABMs are used to record ultrasonic echolocation calls that are produced by bats during their navigation and foraging behaviours. An ABM records the ultrasonic echolocation calls emitted by bats and converts them to frequencies that are audible to humans. An ABM is comprised of two ultrasound sensors and microphones (50 m range), a sound-activated recording device, a timer to turn the system on and off each day, and a rain-noise detector that turns the system off in the event of heavy, persistent rainfall. ABMs record and store data passively and remotely, and have the capacity to record both long-tailed (40 kHz) and lesser short-tailed (28 kHz) bat calls. Nine ABMs (Department of Conservation, ‘Otterbox’ variety in 2011, and later, AR4 in 2017 and 2022) were installed at fixed locations within and around the WNP area, including TSF3; GOP and the NRS (Figure 6) where potential bat passes or potential roosting habitat were considered most likely. The ABMs were set to begin recording 30 minutes before sunset and turn off 30 minutes after sunrise and were left in situ for two to four weeks (Table 8). 3.3.4.2 Bat data analysis ABM data were downloaded and the waveforms analysed using Bat Box 1.0 software (Department of Conservation, 2008). The total number of ‘usable nights’ (UNs) was determined using climate data (CliFlo, New Zealand’s National Climate Database, NIWA) and recording analyses (e.g. when the recorder log indicated a noise switch pause for a period of more than half the night). Nights were considered ‘useable’ if the temperature remained above 5°C and more than half the night was free of rain or insect noise. Each echolocation pass was time (hour/minute/second) and date stamped (year/month/day) providing timing information for activity. 3.3.4.3 Hand held bat detectors Bat detectors were carried opportunistically during all nocturnal VES undertaken for arboreal lizard searches. This survey method was opportunistic because the primary purpose of nocturnal VES was to identify lizards and it is acknowledged that headlight beams may repel bats, however bats have been recorded at other locations where handheld recorders have been used opportunistically (CW pers. obs.). The hand-held recorders used were the BatBox III model, set to 40 kHz, which represents the peak amplitude of their calls. The bat detector’s sensitive microphones pick up a bat’s echolocation calls and convert them into a series of clicks as a bat flies into range (approximately 50 m).
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