LIHUE — The breeding season for some of Kauai’s rarest forest birds is well underway and this year protection efforts by the Kauai Forest Bird Recovery Project will get a boost from a grant by Club 300.
The Swedish organization pledged $5,000 to help KFBRP deal with invasive mosquito and plant species in the Alakai Plateau, a DLNR press release said. Non-native plants such as ginger, create areas of standing water where mosquitoes can breed. Those introduced mosquitoes carry avian malaria which can be fatal for native birds.
“Avian malaria is a serious threat to forest birds,” said KFBRP Project Coordinator Dr. Cali Crampton. “The disease is spread by mosquitoes. Our researchers have been finding mosquito larvae in pools created by invasive plants like Himalayan ginger.”
Native birds evolved in the absence of mosquitoes and they have few defenses against mosquito-borne illnesses. Avian malaria can kill them in just 24 hours.
“Controlling mosquitoes is key to saving our native forest birds from extinction,” Crampton said.
Before western contact, there were no mosquitoes on the Hawaiian Islands. Mosquitoes are thought to have first arrived on a ship that docked in Lahaina on Maui in 1826 and dumped bilge water into a swamp there.
The water contained mosquito larvae. Recent research by KFBRP and partners suggest that weeds make the mosquito problem worse because they slow down streams, creating standing water. Then, the invasive plants shade the pools, so they never dry out. That creates the perfect breeding ground for mosquitoes.
The presence of weeds in the delicate Alaka‘i ecosystem also reduces food availability for forest birds, which rely on native plants such as ohi’a lehua to survive.
Birds which are poorly nourished are more likely to die from disease. Work by KFBRP and Colorado State University suggest that Puaiohi, a fruit eating native thrush, does not eat the fruit of most non-native plants. This species is disappearing from weed-infested parts of its range. Similarly, ‘akeke‘e forages for insects and nests only in ohia lehua, a native canopy tree, which cannot regenerate in heavily weed-infested areas. Non-native vegetation is also less suitable for nesting.
The island of Kauai has lost five of its native birds in recent decades and those that survive are restricted to the Alaka‘i Plateau, a small area of forest at high elevation. In addition to avian malaria, remaining birds are at risk from introduced predators, such as rats and feral cats, and habitat destruction.
Weed removal is good for people too. The forest provides humans with free ecosystem services such as flood water storage, filtration, and fertilization for fields downstream. Invasive plant species upset the delicate balance of the system and can contribute to flooding and other environmental problems on the island.
Since mosquitoes are not native to Hawaii, they are not an integral part of the food chain, so there is no downside to removing them; in fact, there might also be benefits to human health as mosquitoes can vector many human diseases.
“Removing invasive species from this fantastic forest area is a win on so many different fronts and involves many partners,” Crampton said. “We’re delighted to be able to expand our work this year with the help of Club 300 and welcome the international recognition that this grant brings of the importance of Kauai’s native birds.”