Douglas Russell, a senior curator at London’s Natural History Museumwas examining a collection of nests collected on the island of Guam when he made a disturbing discovery.
“The nests were picked up more than 100 years ago, and I assembled them with the aim of adding them to the museum’s main collection. It turned out to be one of the most tragic, saddest accumulations of objects I’ve ever dealt with,” Russell told the Observer last week.
In almost every case, the nests belonged to birds that once flourished on the western Pacific island but are now extinct. “A dozen species, many unique to Guam, have been wiped out since those nests were collected. All that was left was this grim reminder of wildlife that once thrived on the island.”
As for the cause of this devastation, conservationists are to blame brown tree snakes, who were brought to the island on American transports – probably as stowaways on military ships – at the end of World War II. These expert climbers spend their time on high branches, where they eat birds and their eggs. They slowly swept through Guam’s forests during the latter half of the last century.
Large numbers of native mammals, lizards and birds, including the Guam rail and the Guam flycatcher, were wiped out in its wake. Within a few decades, Boiga irregularis silenced the island’s forests.
It is a disturbing story that will be highlighted at Birds: brilliant and bizarre, which opens at the Natural History Museum on May 24. The exhibition will reveal how birds evolved from a group of carnivorous dinosaurs called theropods and eventually spread across the planet to settle on all its continents.
Today there are more than 11,000 species of birds on Earth and the exhibition will reveal the many strange ways they have found to survive. Some bathe in formic acid to kill parasites. Others, like the vampire finch, suck blood for food.
The show will also focus on the impact humans have on birds and their habitats, and the story of the brown tree snake will provide a key display that will include an image of one of the Guam flycatcher nests that Russell studied,’ a symbol of a species lost to the world due to human interference.
“Nests have only one purpose,” says Russell, whose book, Iinteresting Bird Nests and Eggs, will be published in September. “They exist to help nurture future generations of life, and there is something particularly tragic about looking at a nest that will never see a living bird in it.”
Many efforts are being made to restore the plight of Guam’s lost birds, including a international project supported by the Zoological Society of London and several American universities. It aims to return Guam kingfishers to the wild this year using birds bred from members of the species that were rescued just before the kingfishers succumbed to the predations of the brown tree snake. These captive-bred birds will be released on another Pacific island, Palmyra Atoll, which is free from predators.
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However, the loss of these birds has had other worrying impacts on their habitat, as revealed in a paper in Nature communication. Scientists at Iowa State University and other research centers found that the removal of birds that once thrived on local fruits on Guam “resulted in the complete loss of seed dispersal there”. The result was a reduction in the growth of local trees and a major decline in the health of ecosystems across the island, an observation that underscores the key role of birds in maintaining the health of habitats across the planet.
“When you take an entire group of organisms – for example its bird life – out of an ecosystem, you don’t just lose those organisms. The entire ecosystem itself suffers, as we are finding out on Guam,” added Russell.
That’s especially concerning since brown tree snake homes have been spotted in recent years on Saipan, an island north of Guam, Russell added. “There is now a risk, an absolutely devastating one, that brown tree snakes could become established there. And of course this will have a terrible impact on the birdlife and habitats of the island.
“Birds are fantastic creatures, but they are now very vulnerable to the effects of human behaviour. People should come away from the exhibition with a sense that we must learn from our failures, and above all, protect and cherish what we have left.”
