The World's Longest Fences

On our latest show, Ray spoke with Peter Marra of the Smithsonian Conservation Biology Institute about the harm that cats can do to bird populations. Yes, it's sad to say, but those sweet, furry critters kill billions of birds a year in the United States alone. With this sobering statistic on our minds, we were glad to read a recent news item: a five-mile cat fence has been built on Hawaii's Big Island around the Mauna Loa volcano. Whereas individual homeowners can choose to erect fencing to contain their felines, the National Park Service decided to build a single huge one to help protect the endangered Hawaiian Petrel. 

Only about 75 breeding pairs of the Hawaiian Petrel live in Hawaiian Volcanoes National Park, and cats are a serious threat to them. (Many more petrels live outside the park, but the species is still considered endangered.) Cats are not native to the Hawaiian islands, but they have taken nicely to the environment--including learning to scrabble up the sides of volcanoes to hunt vulnerable native species. The Hawaiian Islands are home to several conservation fences, of which the one on Mauna Loa is the longest. The new fence, which took four years to construct, encircles upper Moana Loa, enabling the petrels to rear their young in relative peace. It's six feet tall, with a curved top designed to be impossible for cats to climb. You can read all about the fence's construction here

Pest-proof fencing was pioneered in New Zealand and Australia, where invasive species are a recent enough phenomenon that it is often possible to tell which invader wiped out what native species. While the Mauna Loa cat fence is the longest in the United States, the longest fence of any kind in the world is the Dingo Fence in Australia, which is 3,488 miles long and protects sheep from dingo attacks.

Sacrifice Mosquitoes to Rescue Hawaii's Birds?

Paradise would not be paradise without birds. Unfortunately, Hawaii's native bird population has been dwindling since the accidental introduction of mosquitoes in 1826 by a whaling vessel that dumped maggots into a stream on Maui. With mosquitoes came avian malaria, and with avian malaria came bad news for Hawaii's native birds, which had never encountered any disease like it. The U.S. Geological Survey is now saying that extinction seems to be imminent for some native species, especially on the island of Kawaii, which does not have mountains into which birds can retreat from mosquitoes. 

The Hawaiian archipelago is separated by 2,500 miles from the nearest land. It possesses a diversity of species even greater than the Galapagos Islands; and, like on the Galapagos, these organisms developed in such isolation that they weren’t adapted to the threats brought by Western explorers and immigrants. These days, 434 species of plants and animals are listed as endangered by the United States. More than half the native forest birds are already extinct.

A proposed solution is to create mosquitoes genetically engineered to die off before they reach reproductive age. A group of government officials, conservationists, and scientists in Hawaii are discussing the viability of such an idea. The U.S. Fish and Wildlife Service, which is responsible for endangered species, recently said it was looking at different recovery plans for forest birds. Among these is the mosquito method. 

A decade ago, the U.S. Fish and Wildlife service estimated the cost would be $2.5 billion over 30 years to preserve Hawaii's native forest birds. These plans included buying land and restoring habitats. But genetically modified mosquitoes could be much less expensive.

This is not to say that Hawaiians—or we here at Talkin' Birds, for that matter—are easy with the thought of genetically tinkering with nature. But the fact remains that mosquito technology is a potential fix for human diseases such as Zika. Currently, fighting human disease gets the attention and the funding, but conservation could become just as important a use of this biotechnology.