Estimating the proportion of Archey’s frogs in the Wharekirauponga mine vibration footprint 12 with mixed native scrub (vegetation type M1, m6) during recent nocturnal transects (Figure 6 & Table 4). Estimates of Detection Probabilities During Nocturnal Surveys Estimates of detection probabilities for Archey’s frogs during nocturnal searches are available from three studies (Table 7): two capture-recapture studies[5, 13], described above, and a study[19] using occupancy modelling[20-22] to estimate of detection probabilities and occupancy rates. The estimated average nightly capture probability during the capturerecapture study at Whareorino forest in west Waikato is 0.31 (SE ±0.11) with no behavioural effect (i.e. capture avoidance) observed[13]. The results of re-analyses of Hotham’s (2019) data showed disturbance to frogs during first capture and handling resulted in capture avoidance behaviour during subsequent plot searches, with capture probability declining from 0.336 (SE ±0.10) for first captures to 0.107 (SE ±0.02) for frogs that had been captured during previous searches. As both of the capture-recapture studies involved long and intrusive handling of frogs after their detection and capture, the reported absence of capture avoidance in the Whareorino study is surprising. If capture avoidance occurs during capturerecapture surveys, failure to incorporate it into capture-recapture models will result in inflated population estimates. This could explain the exceptionally high frog density (10,370 ha-1) reported from the Whareorino study. The occupancy modelling study entailed four replicate counts of forty 4×4 m plots in the Coromandel Peninsula during a 5-night period. Frogs were not caught or handled during the study. The reported average detection probability is 0.32 (SE ±0.07). Plot Population Estimates from Replicate Counts and Average Detection Probabilities The number of frogs counted during a nocturnal plot search (C) is a function of (N) the number of frogs present on the plot and the detection probability (pd): C = N/pd. Applied hierarchical or N-mixture modelling methods[23-25] have been developed to provide estimates of detection probabilities and hence numbers of individuals present directly from plot count data. However, the methods require large datasets, with replicate counts from large numbers of plots. These datasets are currently not available for Archey’s frogs in the Coromandel. Although values of detection probabilities for Archey’s frogs vary between nights, estimates of average detection probabilities for nocturnal searches for Archey’s frogs have similar values in three separate studies: 0.310, SE: ±0.11[13]; 0.336, SE: ±0.10[5]; and 0.320, SE: ±0.07[19]. The similarity of average detection probabilities from three independent studies indicates that an average detection probability could be used to derive plot population estimates from counts of Archey’s frogs observed during nocturnal searches of plots. The mean of the three detection probability estimates (0.322, SE ±0.055) was used to derive plot population and density estimates from counts of Archey’s frogs found during nocturnal searches of 99 randomly selected plots at four sites in the Coromandel (Figure 7): Golden Cross, Wharekirauponga, Crosbies and Tapu Ridge. Although the plot locations were selected randomly, many of the plots are close to locations of previous Archey’s frog sightings recorded in the Amphibian & Reptile Distribution Scheme. This is especially true in the Wharekirauponga area where there are 19 records of sighting during 2018 and 2019
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