Life in linear habitats: Spatial ecology of an endangered mammal in a novel landscape
As anthropogenic change pervades the globe, the role of novel habitats in supporting biodiversity is becoming increasingly important. Corridors of retained habitat along linear features such as roads are a common example of what can be important novel habitats in otherwise modified landscapes. Although the use of such habitats by common species is fairly well documented, knowledge about how rare and threatened species operate within them is scant but urgently required for effective conservation and management.
To address this knowledge gap we used the model system of an endangered terrestrial marsupial in a novel landscape in peri-urban Melbourne, Australia. The southern brown bandicoot Isoodon obesulus obesulusis currently persisting within narrow corridors of native and exotic vegetation along drains, roads and railway lines in a region formerly covered by an extensive (30,000 ha) swamp complex. This is despite having recently become locally extinct from a number of large high-quality reserves nearby.
We trapped and radio-tracked bandicoots at six linear sites throughout 2012-2013 to examine their density, residence status, home range and movements. Each site consisted of a narrow vegetated corridor situated within an agricultural and residential matrix.
We captured 89 individual bandicoots over 2492 trap nights and radio-tracked 68 of these. We found that bandicoots living in the linear corridors displayed high site fidelity, maintaining stable home ranges for as long as they continued to be tracked (up to 17 months). While activity was generally concentrated within the vegetated corridors, many individuals included other parts of the matrix within their regular movement paths. Interestingly, the highest abundance of bandicoots was consistently recorded at the site with the most urbanised matrix, which was also where the greatest number of individuals appeared to be utilising anthropogenic food sources (e.g. pet food) in the adjacent residential area. Nesting was largely confined to the vegetated corridors (often amongst exotic plant species), although bandicoots occasionally sheltered under houses, sheds and refuse within the matrix. There was a significant difference between the sexes in length of corridor used, with male home ranges (170-1390m) being longer than female (130-440m).
Our study highlights the potential of novel habitats to provide valuable habitat for biodiversity within modified landscapes, including threatened species. It also reminds us that while the habitat corridors themselves are vital, the matrix can also offer important resources.