Fauna: |
The number of survey sites allocated per patch, were stratified in relation to patch area. Site occupancy and abundance was estimated by actively walking through each site to record and count I. obesulus diggings. Each site was a 100 x 100 m (1 ha) quadrat; the approximate minimum home range size (9 ha being the upper recorded limit) for the species (Paull 2003). To ensure that the majority of each site was surveyed, the GPS ?tracks? function was used. The level of activity at a site was determined by categorising diggings into age classes: fresh (<2 weeks), recent (2 weeks ? 2 months), and/or old (>2 months). The number of diggings was estimated per 100m walked within the quadrat (Paull 2003), but as we were especially interested in confirming the presence/absence of I. obesulus we also estimated digging abundance for the entire 100 x 100 m. These counts were assigned into digging abundance score categories: 0 (0 diggings), 1 (1-5 diggings), 2 (6-20 diggings), 3 (21 -50 diggings) 4, (?51 diggings). Digging records were used to determine site occupancy and the proportion of a patch occupied, based on the number of sites per patch where I. obesulus was present. The percentage of sites occupied within a patch was compared to an earlier survey period by calculating the difference in site occupancy (e.g. proportion of sites occupied in 2016 ? proportion of sites occupied in 2007/08, per patch), to determine whether patch occupancy had decreased, remained stable or increased in 2016. Thresholds of ?30% increase or ?30% decrease were employed (assumed sufficient to account for uncertainty). Previously, digging abundance surveys were undertaken at ~10 year intervals, however during the implementation of the new RAP the frequency is to be increased to; - Mt Burr Range sites in 5 years, and - Nangwarry and Caroline sites on an annual or biennial basis, to help guide any future management strategies within the updated Regional Action Plan. Suggested supplementary method, if the regular digging abundance method fails to detect the presence of bandicoots in a patch: 1. Drive around the perimeter and all internal tracks within the remnant patch, looking for large specimens or groves of Black Wattle (Acacia mearnsii). 2. If and when detected, GPS the location of the tree or grove, and note its characteristics (i.e. single large tree, patch of trees, etc.). 3. Walk around the tree(s) and search for evidence of bandicoot digging activity. 4. Classify digging abundance for the site, within a defined a 1 ha search area2 (to enable the site to be included in the standard method), according to the same scoring categories used for the general survey method (i.e. 0, 1, 2, 3, 4). 5. Repeat method until a Black Wattle grove registers bandicoot activity, at which time that wider patch becomes `occupied? and the supplementary survey can end. 6. If no Black Wattle Groves register bandicoot activity after all tracks have been driven, then the patch remains `unoccupied? and can be more confidently considered vacant for the purposes of monitoring occupancy trends. (for more details refer to Haywood 2017 in particular appendix 2 page 56-57). |