No abstract

The secondary salinisation of wetlands is a global problem that poses a profound threat to freshwater biodiversity. We examined wetland use by diurnal birds in relation to wetland salinity in the Wimmera region of southeastern Australia to better understand the threat posed to biodiversity by secondary salinisation. Forty species of birds were detected in 66 non-riverine wetlands that spanned the broad range of salinities encountered among wetlands in the study region. Use of wetlands by birds was related to conductivity of water using a statistical model that accounted for imperfect detection of bird species during the surveys. Of the 40 species encountered during the study, it was estimated that 20 (95% credible interval 17-24) would respond positively to increasing salinity, and 20 (95% credible interval 16-23) would respond negatively to increased salinity. Expected species numbers are highest in wetlands of intermediate salinity.Our results accord well with our existing understanding of wetland use and salinity for most bird species we encountered, and show that expected future increases in wetland salinity are likely to dramatically alter patterns of wetland use by birds.

Linear clearings associated with roads passing through vegetation communities are known to inhibit movements of many animal species. This can reduce breeding, dispersal and foraging opportunities and lead to population fragmentation, putting further pressure on populations that are small or vulnerable, such as those of threatened species. We tested the prediction that the threatened smoky mouse, Pseudomys fumeus, would not readily cross a 30-m-wide fire break constructed along a ridgeline in eucalypt forest in Victoria, south-eastern Australia. Radio-tracking was conducted along 650 m of the fire break from October to December 2011. We recorded seven individuals that crossed the break. Five individuals fitted with transmitter collars were detected crossing at least twice on 13 of 18 tracking nights. Two animals were found to have crossed by being tracked to nests during the day and/or via trapping. A nearby narrow, unsealed vehicle track was crossed by an additional animal. Our results suggest that it is unlikely that the fire break was acting as a barrier to P. fumeus movements. The presence of fire breaks in P. fumeus habitat may, however, expose individuals to a higher rate of predation when they cross large areas unprotected by vegetation cover.