Translocation of the giant Gippsland earthworm in Victoria, Australia

Summary

The giant Gippsland earthworm (Megascolides australis), a Vulnerable, long-lived, slow-reproducing species confined to about 40,000 hectares of fragmented habitat in southeastern Australia, faced destruction of a large population when a dangerous stretch of the South Gippsland Highway near Loch, Victoria was slated for realignment through its habitat; since an alternate route risked hitting other populations, translocation, never before attempted for this or any earthworm species, was judged the most feasible option. A multidisciplinary team spent 2004 developing extraction methods, finding that pumping water into a trench above the burrows to soften soil enabled the least injurious hand extraction, since the fragile, subterranean worms can only be dug out manually. A receptor site near the original colony was prepared with a matching 1.5-meter soil profile transferred from the source location; between October and December 2005, 901 worms were extracted, with 611 individuals across all age classes plus 18 egg cocoons transferred into a grid of watered, soil-covered holes at the new site. A five-year monitoring program (2006-2011) using manual techniques found evidence of survival and breeding by 2006, an actively breeding population spread across the site by 2007, but only one worm detected during a severe 2008-2009 drought before rainfall in 2009 and 2010 revealed the population had persisted, likely by moving deeper into moist soil. Major difficulties included total absence of prior knowledge about the species' habitat needs, no viable non-destructive monitoring method, and severe drought during establishment. The project rates itself Partially Successful, confirming survival and breeding at least four years post-translocation while longer-term persistence remains unconfirmed.