Long-term effects of warren ripping for rabbit control in semi-arid South Australia.

Abstract

Warren ripping and poisoning were used to control rabbits on the flood-out plain of a major creek system on Manunda Station, a sheep-grazing property near Yunta in semi-arid South Australia. Rabbit numbers were initially reduced by >99 per cent, as indicated by the number of active entrances remaining in rabbit warrens. After nearly 10 years without follow-up control work, ripped warrens had only two per cent of the pre-control number of active entrances. Poisoning effectively reduced rabbit numbers in the short-term, but had no long-term effect on the number of active entrances, either in ripped or unripped warrens. Perennial shrubs regenerated on and around ripped warrens. Warren ripping on this part of Manunda is a cost-effective management option.

Recolonisation of rabbit warrens following coordinated ripping programs in Victoria, south-eastern Australia

“…This effect would be exacerbated at larger distances, which would receive fewer dispersers from the source population and would be predominantly male-biased (Myers et al 1994). This was illustrated in studies of warren ripping undertaken in the arid zone in Queensland and South Australia where ripped warrens were not re-established, even when rabbits had ready access to the ripped areas (Mutze 1991;Berman et al 2011). Mutze (1991) suggested that ripping had changed the soil texture such that burrow establishment was no longer suitable for rabbits.…”

“…This was illustrated in studies of warren ripping undertaken in the arid zone in Queensland and South Australia where ripped warrens were not re-established, even when rabbits had ready access to the ripped areas (Mutze 1991;Berman et al 2011). Mutze (1991) suggested that ripping had changed the soil texture such that burrow establishment was no longer suitable for rabbits. Hence, Berman et al (2011) suggested that ripping of warrens within 1 km of permanent water (a drought refuge for rabbits) would be sufficient to suppress rabbit numbers over a much larger area because rabbits rarely travel further than this in search of water.…”

“…However, the sizes of their study sites were relatively small (50-80 ha) and, hence, recolonisation occurred relatively rapidly because of the short distances (<300 m) between ripped warrens and uncontrolled rabbit populations. Other studies examining the efficacy of warren ripping over larger areas and longer time periods have found that recolonisation rates of ripped areas were low up to 10 years post-ripping (Mutze 1991;McPhee and Butler 2010;Berman et al 2011). With the exception of Mutze (1991), warrens in these studies were ripped using heavy machinery (>100 kW) to depths of at least 70 cm.…”

“…Other studies examining the efficacy of warren ripping over larger areas and longer time periods have found that recolonisation rates of ripped areas were low up to 10 years post-ripping (Mutze 1991;McPhee and Butler 2010;Berman et al 2011). With the exception of Mutze (1991), warrens in these studies were ripped using heavy machinery (>100 kW) to depths of at least 70 cm. McPhee and Butler (2010) examined the effect of different categories of machinery (heavy, medium and light) on the effectiveness of warren-ripping programs over a 10-year period.…”

“…However, there was no analysis of the rates of warren recolonisation in that study. Although the studies of Berman et al (2011) and Mutze (1991) did examine warren recolonisation rates over a longer time interval, neither attempted to explain warren recolonisation with environmental variables.…”