The slippery slope of exporting invasive species: the case of Himalayan tahr arriving in South America

Abstract

Releasing alien mammals was considered positive in the past, but impacts were recognized as important already decades ago. Himalayan tahr were introduced to New Zealand (NZ), resulting in overt damage and continuous government control programs. Existing laws could not prevent NZ exports, and Argentina imports of tahr, although NZ authorities recommended against these imports. National and provincial legislation was possibly too complex, contradictory or incomplete to be enforced, or had loopholes such that tahr were imported to Argentina (2000, 2006). The estimated population in 2008 was 400–450 tahr. As even common travel routes are used to cross national borders in South America illegally with live ungulates, and enterprises importing tahr have been intercepted for illegally transporting wild ungulates previously, there are substantial risks that tahr might be released to new sites. As huge areas lack natural barriers, landscapes are very similar to NZ environments successfully invaded by tahr, and eradication or control are unfeasible, the future of Himalayan tahr in South America now hinges solely on releases or escapes. Importantly, the 2006 import was to Andean foothills which is an ecological time bomb. Considering climates, history of invasiveness in NZ, and low required propagule pressure, tahr could perform from 34°–55°S along the Andes. NZ still has many illegal liberations, thus it would be more difficult to contain illegal liberations in Argentina. It calls for more leadership and better standards by exporting countries, especially if they had the chance to experience the consequences of having received the exotic species earlier.