The Most Endangered Bird: The Fight to Save the Guam Kingfisher

The Guam Kingfisher was never a very widespread bird, limited to the tiny Pacific island of Guam. But when a non-native snake was accidentally introduced to its habitat, the birds were devastated, and the population dropped to just 29 individuals. Today, the US Government is carrying out a massive effort to save the Guam Kingfisher from extinction.

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Guam Kingfisher

The Guam Kingfisher, Todiramphus cinnamominus cinnamominus, is the largest of the three Kingfisher subspecies that are found in the Pacific. It is found only on the island of Guam, where it is known by the natives as the Sihek. Although they are brightly colored with blue backs (the males have cinnamon-colored bellies and heads while the females are cream-colored), the Kingfishers are shy birds who tend to spend most of their time on the ground at the edge of forests, hunting for small lizards and insects. Breeding pairs will nest in cavities that they excavate together in dead trees or in abandoned termite mounds. They are very territorial and will defend their area from other Kingfishers.

Lone males and mated pairs will announce their territory with a loud raspy call consisting of four or five sharp notes followed by four or five softer notes. Most calling is done early in the morning at first light; the birds are so regular that the natives use them to tell the time.

During the Second World War, US Marines invaded Guam and established an important military base there. As a result, large amounts of military supplies and equipment began to flood into the island from other bases in the Pacific. And that resulted in an ecological disaster. Hidden away in some of those shipments were stowaway snakes, Brown Tree Snakes. This is a large arboreal snake, about six feet long, with mild venom, that preys almost exclusively on birds. By the 1950’s, a breeding population of snakes had become established on Guam, and in the absence of their natural predators, they quickly expanded to cover the whole island. Since there were no native snakes on Guam, the local bird species had not evolved any defenses to them, and the snakes soon began depleting the bird populations. One of the hardest hit was the Guam Kingfisher—the Brown Tree Snakes ate the adult birds and their eggs.

In an effort to help the birds, a law was passed in 1960 outlawing the collection or molestation of the birds or their eggs, but this was actually of little help, since the primary problem facing the Kingfishers was the snakes, not the human inhabitants. The population continued to decline, and in 1979 the Guam Kingfisher was listed as an endangered spcies.

In 1981, a US Fish and Wildlife Service team estimated there were about 3,000 birds, a serious drop in population. By 1984, there were only 29 Guam Kingfishers left on their native island, and the birds were listed as “critically endangered”. It was decided by the US Fish and Wildlife Service to capture all of the remaining birds to protect them, and captive-breed them to increase their numbers for release later. A number of captive birds are being bred on Guam itself, but it was decided that keeping all the birds in one place made them too vulnerable to a disease outbreak or accident, so the birds were distributed amongst several different zoos in separate parts of the US.

At first, there were difficulties. The birds breed only once a year, and usually lay only two eggs. these hatch after about three weeks, and the young birds fledge at about one month. The biology and lifestyle of the birds was little-known, however, and zookeepers were unsure what conditions they needed for breeding. As it turned out, the Kingfishers had very exacting requirements for proper nesting trees. Early zookeepers also fed the captives with white mice–this was not a natural food for them, and some of the birds that managed to successfully breed would confuse the mice with their nestlings and accidentally eat their own young. In response, the diet was changed to a more accurate one of small lizards. By 1999, breeding efforts became more successful, and the captive population had grown to about 60.

Today, captive breeding at the Philadelphia Zoo, the Smithsonian National Zoo, the Chicago Lincoln Park Zoo, the San Diego Zoo, Disney’s Animal Kingdom, the St Louis Zoo and others, under the Guam Bird Rescue Project, has increased the Kingfisher population to about 130 individuals. Meanwhile, the Fish and Wildlife Service is trying to eliminate the non-native Brown Tree Snake, and establish a protected refuge in the areas of remaining habitat that can be rendered snake-free. (Feral cats on the island are also a threat to any reintroduced birds, so they are being removed as well.)

So far, however, there has been no reintroduction of Guam Kingfishers, and the birds are completely extinct in the wild. They survive only in zoos.

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