USDA National Wildlife Research Center Symposia


Date of this Version

August 2007


Published in: Witmer, G. W., W. C. Pitt, and K. A. Fagerstone, editors. 2007. Managing vertebrate invasive species: proceedings of an international symposium. USDA/APHIS Wildlife Services, National Wildlife Research Center, Fort Collins, Colorado, USA. Also available online at


Eradication of invasive vertebrate pests from increasingly large islands has become an important wildlife management and conservation tool internationally. Success on islands has prompted attempts to exclude and eradicate vertebrate pests from mainland sites. Early mainland exclusion efforts often failed due to ineffective or poorly maintained barriers to pest reinvasion. Over the last 10 years, we have conducted extensive experiments to design effective pest exclusion technology. We have determined the behavior and physical abilities of many of the vertebrate pest species found in New Zealand and other parts of the world. Pest species have been tested against a variety of fence designs with the aim of developing 100% effective barriers. We found that fences which relied on the use of electrified wires proved ineffective for most species, whereas barriers that exceeded the physical capability of the target pests were reliable. Two multispecies fence designs excluded every pest tested. The designs excluded rodents (including mice), lagomorphs, mustelids, hedgehogs, brushtail possums, cats, dogs, feral pigs, goats, deer, Javan macaque and domestic livestock. The outcome of this research program has been the commercial availability of two designs of Xcluder™ pest proof fence. Supporting components and technology, such as pest-free pedestrian and vehicle gates, waterway gates and remote surveillance systems to mitigate reinvasion risks have enabled projects to succeed. Over 20 exclusion barrier systems have now been constructed in areas up to 3,400 ha in size and have allowed multi-species eradication attempts. With the successful removal of vertebrate pests, many projects are now undertaking significant restoration programs including the reintroduction of threatened wildlife species to mainland sites.