David J. Flaspohler, an avian ecologist and conservation biologist at Michigan Technological University, writes from Hawaii, where he is studying the influence of human activities on birds and the natural ecosystems that support them.
Monday, May 21
This morning, we have driven the four-wheel-drive truck up the 35 miles and 5,000 feet of elevation from Hilo to the turn onto a gravel road that will take us back to the study area. We pass through the gate, enter the Upper Waiakea Forest Reserve, and begin to pick our way across a road bulldozed across the lava. Sitting in the truck as it rumbles and creaks over this road, you are in a constant state of motion, jostling against the person sitting next to you, the truck door and, if you are not wearing your seat belt, the roof. To the farthest kipuka, it is about 30 minutes on this lava road. From there, it is a 45-minute hike across boot-shredding lava to the most distant kipuka.
In bird research, you don?t lift anything heavier than a pair of binoculars. Here, the hardest days are when we move the mist-net poles, nets, sledgehammer, and the bird banding kit to the most distant kipuka. Mist nets are fine nets that were invented in Japan in the 1600s and made of silk to catch small birds for food; they?re now made of nylon, adapted by 20th-century researchers as a way to humanely capture birds for measurement and marking. After banding for two days in one of the 34 kipuka involved in our studies, the poles, nets, sledgehammer and banding equipment are hiked across the lava to set up in another kipuka.
Our poles are made of galvanized electrical conduit pipe, and because most Hawaiian forest birds spend their time in the tall forest canopy, we use double- or even triple-high mist nets to reach 25 feet up. Once in the kipuka, we search for a natural net lane in the forest. Two people work to thread the net over the poles, and raise and steady the poles with guy ropes. A rope and pulley system is used to raise the net, and to lower it when a bird is caught.
To date, we have banded about 1,500 birds over two breeding seasons, each released with a unique combination of colored bands so it can be identified when it is sighted again. From this information, we can estimate annual survival and adult and juvenile dispersal.
We are also monitoring nests to estimate success and to see if the presence of nonnative rats influences nest success; rats will eat eggs, nestlings and even adults if they can catch them, as rats can climb trees. Half of the kipuka we?re studying have rats, and half had rats removed. The long-term viability of these bird populations will be determined by whether survival and reproduction are sufficient to compensate for mortality and nest failure. Just 20 miles away, the i?iwi, a common bird in these kipuka, has all but disappeared from Hawaii Volcanoes National Park, evidence that survival and reproduction were insufficient to sustain that population.
As I cross the lava, balancing 30 pounds of poles on my shoulder, I glance up at the broad shield volcano Mauna Loa and consider an amazing bit of irony. Visible on the volcano is the oldest atmospheric carbon dioxide monitoring station in the world. Data from this station provided one of the first pieces of evidence that the carbon dioxide was increasing in concentration. It might seem that a bit of warming would pose little threat to tropical birds, if not for Captain Cook and British imperial ambitions.
Cook was the first European to stumble across the Hawaiian Islands in 1778, and his arrival brought a new era of exotic species introductions, malaria-carrying mosquitoes among them. Mainland birds have their own variety of malaria, but after long exposure it is rarely fatal. In contrast, native Hawaiian birds have almost no resistance. Since the early 1800s, the exotic Plasmodium and its tropical mosquito vector (Culex quinquefasciatus) have contributed to the extinction of at least a dozen endemic Hawaiian birds and have all but eliminated the remaining species from the warm lowlands.
For now, tropical Culex cannot survive the cooler temperatures at our field sites above 5,000 feet. Above 9,800 feet, trees and the birds that depend on them disappear. So today, native birds with no resistance to malaria are confined to a narrow elevational band. Under many warming scenarios, this refugia promises to narrow or even disappear as Culex is able to move upslope, leaving the ultimate fate of these remarkable birds to an human-mediated endgame between the parasite and the na?ve immune systems of Hawaii?s surviving birds.
Considering the carbon dioxide station some miles away, I wonder at the cruel calculus of all of these forces, set in motion by the ambitions of men centuries ago and poised to erase a wonder of evolution that will never come again. Yet seeds of hope have been found within the genetic blueprint of some Hawaiian birds. The apapane and Hawaii amakihi have shown some genetic resistance to malaria. If hope is indeed the thing with feathers that perches in the soul, as Emily Dickinson wrote, then these birds may be its perfect embodiment.
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