Winter distribution of small mammals in relation to snow cover in the subalpine zone, Australia

Abstract

We present the results of a study that is the first to investigate the landscape-scale distribution of small mammals in direct relation to the spatial and temporal variation of snow cover. We investigated the distribution of the dusky antechinus Antechinus swainsonii and bush rat Rattus fuscipes in the subalpine zone of Kosciuszko National Park in the Snowy Mountains of south-eastern Australia. A new hair tube technique was used to detect the presence of small mammals active in the subnivean space. In 2002, we sampled 72 sites stratified by elevation (1501-1600, 1601-1700, 1701-1800 m), aspect (accumulating, ablating) and habitat type (woodland, wet heath, dry heath, grassland). These factors were considered important in influencing snow accumulation and generally reflected the types of habitats available to small mammals. In 2003, the presence of small mammals was investigated at 30 high-elevation sites including six boulderfields. The development of the subnivean space in the Snowy Mountains is dependent on the presence of structures such as shrubs, boulders and microtopographic features that are capable of supporting a snow layer above ground level. When snow was present, small mammal detections were negatively correlated with snow depth and duration, and positively correlated with the complexity of structures and microtopography. At high elevations detections were largely confined to boulderfields, and at mid and low elevations small mammals were detected primarily in habitats where the subnivean space was most extensive. Antechinus swainsonii and R. fuscipes responded differently to snow cover, with the latter seeming better able to overwinter where snow cover was shallow and patchy, in contrast to A. swainsonii whose occurrence was correlated to the size of the subnivean space.

Immediate and short‐term responses of bird and mammal assemblages to a subalpine wildfire in the Snowy Mountains, Australia

“…The unburnt habitat least used by small mammals (grassland) had a larger subnivean space and was not significantly different to the burnt wet heath (Fig. 4) which, when unburnt, was the habitat most used of the four by small mammals during the nival period (Sanecki et al 2006).…”

“…that had been established for a previous study of small mammal distribution during winter (Sanecki et al 2006). We selected five burnt and five unburnt replicates of each of the four major habitat types present in the subalpine zone of the Snowy Mountains (wet heath, dry heath, seral woodland, grassland).…”

“…The data from the present study show how winter-active small mammals above the level of the winter snowline, are totally dependent on the balance of the suite of edaphic and biological components in their habitat for continued existence. The interaction of snow cover, as insulation and in restricting foraging, shrub cover which allows for the formation of greater subnivean space (Green & Osborne 1994;Sanecki et al 2006), and the presence of an introduced predator can only work in relative equilibrium in the absence of, or long time interval between, fires. Fires in other Australian ecosystems have a varying impact on small mammal populations.…”

The influence of snow cover on home range and activity of the bush-rat (Rattus fuscipes) and the dusky antechinus (Antechinus swainsonii)

“…The study area is a remnant patch of subalpine vegetation that was not burnt, ~400 m by 150 m in size, and consists of a mosaic of vegetation communities typically found at this elevation (Sanecki et al 2006a). Wet heath occurs along the creek and in other poorly drained locations, interspersed with areas of dry heath and tussock grassland where soils are better drained.…”

“…In a landscape-scale study of small mammal distribution in relation to variations in snow-cover conditions, it was observed that once snow cover was established, small mammals were virtually excluded from habitats without shrub layers that permit the development and maintenance of a sufficiently large subnivean space (Sanecki et al 2006a). These findings suggest that the subnivean space may not be as extensive as previously thought by Green and Osborne (1994).…”