Jan TenBruggencate explains why the benefits of conservation action outweigh the potential risks on Lehua Island.
By: Jan TenBruggencate
The removal of rats from Lehua Island should proceed, in my view. The likely benefits are huge, and the theoretical risk is small. Invasive rats on Lehua are killing live seabird chicks, eggs and adults, eating native plants and seeds, and feeding on native insects. There are horrific images of chicks with their heads chewed off, and seabird eggs drained of their contents. Rats are ruining the island environment, promoting sediment runoff into the ocean and reducing the density of seabird flocks our fishermen depend on to locate schools of fish.
The Department of Land and Natural Resources proposal for removing the rats is no edgy experiment.
It has been tested, refined, and safely employed repeatedly, including on several islets around Hawaii. It involves dropping an anticoagulant called diphacinone in a bait pellet that is attractive to rats.
These techniques — dropping rat bait on the island — succeeded in removing rats from Mokapu off Molokai and Mokolii off Oahu. Essentially the same technique removed rats from Midway and Kure at the other end of the Hawaiian archipelago. This form of conservation intervention has also benefited Palmyra Atoll to the south of Hawai’i, multiple islands around New Zealand, and several hundred other small oceanic islands.
Nearshore waters have been tested after these rat bait drops. The bait dissipates in water in minutes and is chemically undetectable in hours or days.Tests after the bait was used on Hawaiian islands found no negative impact on marine life. The abundant corals off Palmyra were tested and suffered no impact at all, despite bait applications far more dense than are proposed for Lehua.
There certainly are risks. A few non-target animals could theoretically be impacted, but that has not been a significant issue in other Hawaiian island applications or on other islands in the Pacific. The risks are well understood and are minimal.
Please read the environmental assessment. It is more than 100 pages long and it’s dense, but it clearly lays out the project, its risks, and its benefits.
Doing nothing is a miserable option. Rats are all-purpose predators—they eat birds and seeds and insects. They even eat crabs and opihi off the rocks.This limited, short-term project offers significant long-term gains for the local environment. We can restore Lehua’s native dryland forest, allow its native bird rookeries to recover, improve shoreline marine life survival, enhance our fishing community and help refill the skies with native birds. That is something we can be proud of, a problem we can solve today that will create benefits for generations to come.
- Palmyra Rat Eradication Rids the Atoll of Disease-Carrying Mosquitoes - March 15, 2018
- The Invasive Rats of Lehua Appear to Have Taken the Bait - October 19, 2017
- Lihue Resident Advocates for Lehua Island Restoration - August 15, 2017