Do utility corridors affect movements of small terrestrial fauna?

Abstract

Linear forest clearings created by utility corridors have the potential to fragment landscapes, create edge effects and isolate populations of plants and animals. Here, we investigated the impact of utility corridors on small terrestrial fauna inhabiting Nangwarry Native Forest Reserve, south of Penola in south-eastern South Australia. Twelve sites straddling linear clearings of two widths (1.5 and 4.2 m) were surveyed over 2 years with 53 traps arranged as five transects at each site. This resulted in a total of 933 captures of 18 vertebrate species, including four amphibians, eight reptiles and six mammals. Propensity for capture near edges v. interiors, distances moved between recaptures and willingness to cross linear clearings varied among species, and was not related to taxa groups. For example, the small skink Bassiana duperreyi was extremely mobile and crossed tracks regularly. At the other extreme, the frog Neobatrachus pictus was more likely to be caught on interior transects and was never recorded moving between captures. The small dasyurid Antechinus flavipes was the most regularly caught species, and made both short- (<50 m) and long-distance (>1500 m) movements, with longer moves made by dispersing juveniles. Movements by this species often involved clearing crossings, although these were more likely when time between recaptures was longer, particularly for females. However, the overall rate of crossings for this species was not different from that expected if movements were random. In conclusion, the relatively narrow utility corridors studied here did not appear to affect the mobility of the majority of vertebrates significantly, with approximately half of the 85 movements recorded being of animals crossing a clearing, and no significant difference between the proportion crossing the wider (4.2 m) and the narrower (1.5 m) clearings. The present study is one of only a handful investigating movement patterns in reptiles and amphibians, particularly in relation to disturbances. However, sample sizes were small for some species, and future work should focus on those species that look to be either particularly mobile or sedentary, and encompass responses to the wider (up to 15 m) permanent tracks in the region.