Hawaiian Petrel faces uncertain future.They were said to have darkened the skies as large flocks flew overhead. Hawaiian petrels (Pterodroma sandwichensis) are remarkable seabirds that travel as far as the Aleutian Islands in Alaska to obtain food for their young, and then return each year to the Hawaiian Islands to breed. While bird enthusiasts hope to hear the rhythmic vocalization of a petrel or spot it returning to its colony after a long foraging trip at sea, researchers probe the mysteries surrounding this species. What is its preferred breeding habitat? Where does it go at sea? Has its diet and foraging range changed over time? What is its impact on the surrounding ecosystem? Answering these and many other questions will help protect the Hawaiian petrel, but for some of its colonies, time may be running out.
Now a rare sight, Hawaiian petrels are restricted to high-elevation regions on several of the main islands. The birds nest in burrows within remote areas of forests and on the high slopes of volcanoes. Their dwindling habitat has resulted in a drastic population decline for a bird that may once have numbered in the hundreds of thousands or even millions. Today, an estimated 19,000 individuals remain, and the species is listed as endangered. Continued habitat modification, the spread of invasive species, and predation by non-native mammals threaten the remaining colonies. Their story is part of the greater biological destruction taking place on the Hawaiian Islands, endangering much of the biodiversity that remains.
According to the American Bird Conservancy, one-third of the birds found on the U.S. endangered and threatened species list occur only in Hawaii. An astonishing 344 species of plants and animals found in Hawaii, from snails to trees, are listed as endangered or threatened, more than in any other state. As development proceeds at a dizzying pace and natural communities are overrun by non-native plants and animals, many of the endangered species are on the brink of disappearing.
One example is the po'ouli (Melamprosops phaeosoma), a Hawaiian honeycreeper. This forest bird species has not been seen since 2004, and biologists do not know if it survives. An attempt by conservationists to breed the bird in captivity did not succeed. Driven from its preferred habitat, the po'ouli became restricted to a cold, wet area where it slowly declined. Researchers now suspect this area was secondary habitat at best, not capable of supporting the population. Such cases reveal that some modern bird habitats on the islands may be quite different from their natural habitats in the past.
The po'ouli is just one example of species decline due to ecosystem modification. Biodiversity loss is compounded as ecological relationships among different organisms deteriorate. Pollination rates and dispersal of plants have changed due to lower bird populations. Consequences from a reduction in nutrient flow from the ocean to the forests because of seabird declines are still being determined. Decreases and extinctions of certain species have resulted in the decline of entire ecological communities. As Jonathan Price, assistant professor of geography at the University of Hawaii-Hilo, says, "We are dealing with ecosystems that are just unraveling."
The drastic change of Hawaii's environment since human arrival has focused attention on preserving and restoring the islands' natural history. Over the past 30 years, paleontologists Helen James anal Storrs Olson of the Smithsonian Institution have uncovered and described around 40 extinct bird species that once inhabited the islands. Many more are still to be described. Their research has not only given a glimpse into the past life that existed on these islands but has laid out a picture of what Hawaii should look like, giving conservationists a baseline from which to tailor programs for conserving biodiversity.
"In order to create a healthy forest for these species, we need to understand what was the functional ecology of the past," said James. This means identifying what a natural Hawaiian ecological community consisted of and preserving and restoring these communities.
For the petrels, current observations indicate their natural habitat is high-elevation regions. But ancient bird bones belonging to the species have been uncovered from the coast to the mountains on many of the islands. It appears that, like other species of Hawaiian birds, the petrels were driven out of their natural homes and now congregate on the diminishing areas of habitat that remain.
Erecting fences to keep out non-native ungulates, shielding streetlights to avoid blinding the birds and collisions, and maintaining existing colonies will assist in the struggle to protect the petrels. Encouraging these seabirds to breed in predator-free areas and restoring former habitat for colonies may help them extend their range.
"If I think things are looking better, it's because many people and many resources are focused on preserving this and other species," said Dr. Nick Holmes of the Kaua'i Endangered Seabird Recovery Project. "And the new information that science is providing plays a key role in helping to achieve effective conservation because it supplies invaluable context for interpreting what's important."
But, said Holmes, the trends of habitat loss, encroachment by non-native plants, and predation by introduced mammals threaten to undo conservation efforts. Greater assistance from federal, state, and local governments to prevent the introduction and spread of invasive species is needed. In addition, public outreach and education on the unique natural wonders of the islands, and the problems they face, helps to generate public support for the long-term efforts necessary for healthier ecological communities in Hawaii.
Editor's note: This edition of the Bulletin features several examples of progress in recovering Hawaii's endangered birds. The following article points out, however, that significant challenges remain.
Matthew Cimitile, an environmental journalism graduate student at Michigan State University, can be reached at 813-368-9560 or email@example.com