The Endangered Endemics and the Aggressive Invader

by Jim Haw
Originally published at ScientificAmerican.com

Guam is 17 hours ahead of Los Angeles, and even our USC students were up early (or at least on time) for our first morning in Micronesia. After a generous and very international buffet breakfast in the Hilton we walked out into intermittent squalls and boarded our charter bus to the Guam Department of Agriculture. There we were met by Dave Ginsburg’s long-time friend and colleague, Brent Tibbatts of the Division of Aquatic and Wildlife Resources.

Senior environmental studies major Raquel Rodriguez holds a ko’ko’ (Guam Rail) as other students in our course gather around. Photo by Jim Haw.

This first morning on Guam was devoted to threatened and endangered terrestrial species. For millennia, Guam was devoid of predators. The Guam Rail, a flightless bird locally known as the ko’ko’, thrived. But not long after World War II, a gravid brown tree snake — a viper native to Papua New Guinea and coastal Australia — entered Guam with a cargo shipment. With almost no predators, and an abundance of birds indifferent to the snake such as the ko’ko’, its population exploded at the expense of the birds.

The ko’ko’ was further threatened by feral cats, human consumption and habitat loss. By the time a conservation effort was organized in the 1980s, only 10 individuals could be found, from which all surviving ko’ko’s are descended.  Currently the Division of Aquatic and Wildlife Resources is breeding 107 ko’ko’s in captivity, and small populations have been reintroduced into several locations in Micronesia.

One of the last two Mariana crows on Guam morns the death of his mate a few days earlier while perched in his enclosure. Photo by Jim Haw.

We saw two other critically endangered bird species at the Guam Department of Agriculture. Modeling studies suggest that the Mariana crow will likely become extinct later this century. In fact, the last female Mariana crow on Guam died on Friday, leaving her mate, who we saw, in obvious distress. He might be moved to another island to be paired with a female there.

We also saw Guam Micronesian Kingfishers, a species of bird that survives only in a globe-spanning network of captive breeding programs at zoos and at the Department of Agriculture.

Wildlife biologist Suzanne Medina introduced our students to a ko’ko’ who is more accustomed to being handled by humans. Our students immediately fell in love with the bird.

Guam wildlife biologist Seamus Ehrhard (left) introduces a venomous brown tree snake to Kim Knabel, a double major in environmental studies and environmental engineering. Photo by Jim Haw.

Not to be outdone, Seamus Ehrhard, another wildlife biologist, brought out a 6-foot brown tree snake for us to see and handle. This snake is a viper, but its fangs are in the back of its mouth, and injecting its venom into humans typically requires chewing rather than a simple strike.

Adult humans, when envenomed, usually experience mild symptoms — little worse than a bee sting. Nearly all of our students interacted with the snake, some immediately and others with a little bit of hesitation. This encounter was under the control of a professional wildlife biologist. Uncontrolled, the brown tree snake has a reputation as an aggressive animal — quick to strike, and strike and strike again.

The last animal we interacted with might be one of the most endangered mammal subspecies in the world. The Mariana fruit bat is listed as threatened by the U.S. Fish and Wildlife Service, with most of the remaining individuals on several of the islands in the northern Marianas.

Wildlife biologist Suzanne Medina introduces one of the last eight remaining Guam fruit bats to the USC students. Photo by Jim Haw.

The Guam Mariana subspecies has 8 remaining individuals, 7 in the wild, and a single captive male rescued following a typhoon some 14 years ago. Suzanne brought out this individual for us to observe, but handling the bat requires special attention as it can bite. Human consumption, brown tree snakes, other invasive species, habitat loss and possibly disruption of resting sites by aircraft noise have all but wiped out this beautiful creature.

Of the threatened animals we met, the ko’ko’ has the best chance of survival because it can produce several egg clutches per year, and the survival rate of young birds is reasonably high. Advances in captive breeding strategies must be found for the Guam Kingfisher, or this species will soon be gone.

On the nearby island of Rota people are apparently deliberately killing some of the remaining Mariana crows, and this species could soon be lost from the wild or entirely. One of the best potential habitats for preserving the crow in the wild is on U.S. Air Force property on Guam, but the U.S. Department of Defense prohibits the reintroduction of endangered species onto their property.

There is no hope or expectation that the Guam subspecies of the Mariana fruit bat will recover. The brown tree snake however remains plentiful, and it is blamed for many of the numerous power outages on Guam, some indeed caused by the arboreal snake shorting out power transmission lines.

For our students, the value of today came not only in bearing witness to animals that will likely become extinct in their lifetimes; it came in meeting selfless and hardworking professionals such as Brent, Suzanne and Seamus who are trying to make a difference — whatever the odds against them.

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