Key Benefits of Eradication
The many successful rodent eradication programmes undertaken on islands around the world have shown that the benefits to humans and native plants and animals are both significant and immediate. Benefits include (see review in Towns et al. 2006):
- significant increases of seeds and seedlings of numerous plant species on islands after the eradication of various rodent species
- rapid increases in the number of ground lizards (e.g. geckos, skinks) following removal of rats – including a 30-fold increase in one case
- dramatic increases in the numbers of breeding seabirds and fledging success
- rapid increases in forest birds and invertebrates.
Other than the benefits to biodiversity, the proposed eradication operation was considered the most appropriate course of action for a range of social, health and financial reasons.
The anticipated benefits specifically relating to a rodent eradication programme on the LHIG include:
- recovery of a range of species an ecological communities directly at risk of extinction due to rodents such as the LHI Placostylus, Little Mountain Palm, Phillip Island Wheat Grass and Gnarled Mossy Cloud Forest
- a marked increase in birds, reptiles and insect density, diversity and distribution – this boost in diversity will increase food resources for predatory terrestrial vertebrates and potentially lead to population increases which will enrich the experience of both island residents and tourists
- increases in the abundance of plants, seeds and seedlings, thereby enhancing the process of forest regeneration
- removal of the economic and environmental burden of the ongoing control currently in place, eliminating the need for the ongoing use of rodent poisons in the environment and their associated long-term risks to native species, pets, livestock and people
- an increase in productivity in the island’s Kentia palm industry and returns to the local community
- the ability to return species (or closely related surrogates/ecological equivalents) that have long been absent due to the predation of rats and mice, such as the Island Gerygone, Grey Fantail, Boobook Owl, LHI Wood-feeding Cockroach and LHI Phasmid
- elimination of possible health issues and amenity impacts to tourism operations caused by rodents, including a range of viruses, bacteria, internal parasites (such as intestinal worms) and external parasites (such as fleas, mites and lice), many of which can spread disease to humans
- elimination of the inconvenience currently experienced by residents caused by spoiled foodstuffs and rodent excrement – keeping rodents out of dwellings has been an ongoing task for the island’s residents.
- increased agricultural productivity
- increased tourism by marketing a rodent free World Heritage Area.
- Removal of ongoing poison in the environment and associated control costs. The Lord Howe Island rodent control program (excluding residents’ own poison usage) has used more than 130 tonnes of poison over the last 30 years costing over $2 million dollars.
- An end to rodenticide resistance on Lord Howe. Mice have become resistant to warfarin due to over exposure in previous control programs and recent testing has shown an increase in resistance to brodifacoum in the settlement area where residents use Talon (brodifacoum based) to control rodent numbers.
- Long term positive impacts for tourism through protection and enhancement of World Heritage values and improved visitor experience. For example, on Ulva Island in New Zealand, an eradication of rodents was undertaken in 1996. The success of the eradication, and subsequent reintroduction of species lost from the island as a consequence of rat predation, has resulted in the island becoming a premier tourist location. Tourist numbers increased from around 10,000 to 30,000 per year in the decade after rat eradication. This boost in tourism resulting from ecosystem recovery sustains 17 new businesses.