Recently I had a chance to read Chasing the Ghost Birds, a new book by David Sakrison. Part environmental essay and part adventure tale, the book follows reintroduction programs for three species: trumpeter swans, Siberian cranes, and whooping cranes. The species are linked by their appearance (all being large white birds) and by some key people and organizations who were involved with two or more of the projects.
Trumpeter swans thrived in Alaska, but had mostly disappeared from their historical range in the lower 48 states by the early twentieth century. The one exception was a small population centered around Yellowstone National Park. In the 1980s, biologists in the midwest began programs to reintroduce breeding trumpeter swans - first in Wisconsin, and subsequently in Michigan, Iowa, and elsewhere. Eggs were taken from nests in Alaska and flown to the midwest to be incubated and raised in captivity, and then released in local wildlife refuges. The program has been successful in establishing a self-sustaining breeding population.
With Siberian cranes, the goal was to create a stable captive flock that can serve as a genetic base if reintroduction becomes necessary. Wild flocks are large enough that extinction is not an imminent threat, but small enough that the population is vulnerable. Siberian cranes posed some unique challenges, compared to the other species profiled. Many of the breeding grounds are inaccessible, migration routes are not well known, and conservation requires cooperation across sometimes-hostile borders. In addition, cooperation between the U.S.-based International Crane Foundation (ICF) and Russian scientists required special permissions from both the Russian and American governments to transport crane eggs from Russian breeding sites to the ICF headquarters in Wisconsin.
The whooping crane faced a true crisis. By the mid-twentieth century, its population was reduced to a small migratory flock that wintered in Texas and bred in Canada. At that point there was a real issue of declining genetic diversity. With the numbers so small, one catastrophic event could push the species to extinction. Conservation plans focused on the protection of the existing flock and the establishment of migratory and non-migratory flocks in the East. After some trial and error, the whooping crane team settled on a program of releasing hatch-year captive-bred whooping cranes in Wisconsin and then leading them south to Florida with an ultralight aircraft. (The annual journeys are chronicled at Operation Migration.) Whether the project will ultimately be successful in creating a stable migratory flock remains to be seen, but the results so far look promising.
All three of the species profiled in Chasing the Ghost Birds benefited tremendously from the willingness of volunteers to donate time and resources towards long-term projects. The biggest contributions came from Terry and Mary Kohler, who provided private plane transportation to shuttle wildlife biologists between various egg-collecting sites and captive breeding centers in Wisconsin and Maryland. Efforts on behalf of the whooping crane also received a boost from experiments initiated by private pilots who devised the method of leading cranes by ultralight. In a time of tight budgets for wildlife agencies and increasing numbers of species at risk, this type of private initiative - working in conjunction with qualified biologists - may be necessary to complete important conservation work.
David Sakrison, Chasing the Ghost Birds: Saving Swans and Cranes from Extinction. Ripon, Wisconsin: Watson Street Press, 2007. Pp. xvi, 283; maps and photographs. $16.50. ISBN: 0979279909