ANDERSEN AIR FORCE BASE, Guam » Dead mice laced with painkillers are about to rain down on Guam’s jungle canopy. They are scientists’ prescription for a headache that has caused the tiny U.S. territory misery for more than 60 years: the brown tree snake.
Most of Guam’s native bird species are extinct because of the snake, which reached the island’s thick jungles by hitching rides from the South Pacific on U.S. military ships shortly after World War II. There may be 2 million of the reptiles on Guam now, decimating wildlife, biting residents and even knocking out electricity by slithering onto power lines.
More than 3,000 miles away, Hawaii environmental officials have long feared a similar invasion — which in their case likely would be a “snakes on a plane” scenario. That would cost the state many vulnerable species and billions of dollars, but the risk will fall if Guam’s air-drop strategy succeeds.
“We are taking this to a new phase,” said Daniel Vice, assistant state director of U.S. Department of Agriculture’s Wildlife Services in Hawaii, Guam, and the Pacific Islands. “There really is no other place in the world with a snake problem like Guam.”
Brown tree snakes are generally a few feet long but can grow to be more than 10 feet in length. Most of Guam’s native birds were defenseless against the nocturnal, tree-based predators, and within a few decades of the reptile’s arrival, nearly all of them were wiped out.
The snakes can also climb power poles and wires, causing blackouts, or slither into homes and bite people, including babies; they use venom on their prey but it is not lethal to humans.
The infestation and the toll it has taken on native wildlife have tarnished Guam’s image as a tourism haven, though the snakes are rarely seen outside their jungle habitat.
The solution to this headache, fittingly enough, is acetaminophen, the active ingredient in painkillers including Tylenol.
The strategy takes advantage of the snake’s two big weaknesses. Unlike most snakes, brown tree snakes are happy to eat prey they didn’t kill themselves, and they are highly vulnerable to acetaminophen, which is harmless to humans.
The upcoming mice drop is targeted to hit snakes near Guam’s sprawling Andersen Air Force Base, which is surrounded by heavy foliage and if compromised would offer the snakes a potential ticket off the island. Using helicopters, the dead neonatal mice will be dropped by hand, one by one.
U.S. government scientists have been perfecting the mice-drop strategy for more than a decade with support from the Department of Defense and the Department of the Interior.
To keep the mice bait from dropping all the way to the ground, where it could be eaten by other animals or attract insects as they rot, researchers have developed a flotation device with streamers designed to catch in the branches of the forest foliage, where the snakes live and feed.
Experts say the impact on other species will be minimal, particularly since the snakes have themselves wiped out the birds that might have been most at risk.
Scientists from the Smithsonian using DNA data sets to outline the evolutionary family tree of the Hawaiian honeycreeper have determined that the 56 species of the native bird evolved from the Eurasian rosefinch.
In another important finding, the researchers linked the timing of the evolution of the honeycreeper to the formation of the four main Hawaiian Islands.
“It was fascinating to be able to tie a biological system to geological formation and allowed us to become the first to offer a full picture of these birds’ adaptive history,” said Helen James, a research zoologist at the Smithsonian’s National Museum of Natural History and an author of a paper on the study.
Fern Duvall, state Forestry and Wildlife Division wildlife biologist, who was not involved with this study but is working with two of the authors of the paper, James and Rob Fleischer, on a similar project with shorebirds, called the findings “dynamic” and “unique.”
Putting the research in context, Duvall noted that many bird experts believed the honeycreepers to be descendants of the house finch of North America. Instead, the researchers say the Eurasian rosefinch from Asia is the mother bird of the species.
As for the evolutionary discoveries, Duvall said it had been theorized that there was a link between the biologic and geologic development of the birds to the islands. The scientific connection made in the study is new, he said.
“For them to show that that is the case is dynamic,” he said Wednesday. “I think it’s an excellent example that birds’ forms are tied to diverse habitat types.”
Endangered species hotspot now guarded against goats, pigs
A new pair of fences in the remote wilderness of Kaua‘i will reportedly protect the island’s primary source of water and one of the most important biological diversity hotspots in the Hawaiian archipelago.
These strong barriers, developed by The Nature Conservancy for the benefit of the Kaua‘i Watershed Alliance, will shelter 8,000 acres of the state’s most pristine wildland from the onslaught of invading feral animals, a news release states.
“These are just amazing areas. Everywhere you look, you are surrounded by incredible native Hawaiian birds, plants and insects. There is nowhere in the state like quite like it,” said Jeff Schlueter, Kaua‘i natural resource manager for The Nature Conservancy.
Ken Wood, a prominent biologist with the National Tropical Botanical Garden, which is a key partner in the Kaua‘i Alliance, said the biological diversity of the region is remarkable. He calls the area “one of the most important conservation sites in the entire archipelago.”
This land is also the core of the island’s watershed, a place where abundant rains and mists are soaked up and then feed the island’s rivers and its aquifer.
“These fences were conceived to protect the primary source of the island’s water supply.
What began as a handful of wetland ponds with dozens of birds overlooking Pearl Harbor has turned into a refuge teeming with hundreds.
The number of native birds, including endangered Hawaiian stilts called ae o, in the ponds at Waiawa and Honouliuli at the Pearl Harbor National Wildlife Refuge has been rising since the early 1990s, when a conservation recovery plan was developed, said David Ellis, refuge project leader.
Federal wildlife officials built fences to help keep out predators and began controlling invasive plants and managing water in the ponds.
“There’s been a very noticeable increase,” Ellis said. “There used to be only a few wetland birds that used these ponds ; now we commonly see hundreds, an important step for endangered species.”
In the late 1920s, people intentionally introduced birds known as Japanese white-eyes into Hawaiian agricultural lands and gardens for purposes of bug control. Now, that decision has come back to bite us. A recent increase in the numbers of white-eyes that live in old-growth forests is leaving native bird species with too little to eat, according to a report published online on September 17th in Current Biology, a Cell Press publication. The findings show that introduced species can alter whole communities in significant ways and cause visible harm to the birds that manage to survive.
"Native Hawaiian songbirds cannot rear normal-size offspring in the presence of large numbers of introduced Japanese white-eyes," said Leonard Freed of the University of Hawaii at Manoa. "Their growth is stunted."