Though Time in Captivity was Short, HR-2 Gave Researchers Much to Ponder

posted in: March 2005 | 0

Although the po‘ouli known as HR-2 did not live long in captivity, it was able to provide researchers with much valuable in formation and, in the case of the cryogenic tissue library of the San Diego Zoo, with cells that may some day be used to bring life back to the species.

Here are a few of the side issues that may, as efforts to save rare bird species progress, prove to play a key role.

Malaria: This is a bad-news, good-news development. It turns out that HR-2 had a low-grade, sub-clinical infection with avian malaria – an infection that almost certainly was contracted years earlier from a mosquito bite in the bird’s east Maui habitat. The bad news, of course, is that this means that mosquitos carrying avian diseases are probably far more commonplace in the east Maui rain forests than tests done a decade ago indicated. The good news is that the bird had survived the infection, suggesting that the po‘ouli and, perhaps, other native birds may have some resistance to the disease.

Cloning: Within hours of the bird’s death, staff with the Conservation and Research for Endangered Species Department of the San Diego Zoo had removed tissues from the bird and had begun culturing them. According to the zoo, “Each tissue was then minced to release cells that were then placed into a nutrient solution and incubated.” After incu bation, the cells were frozen and stored at a temperature of minus 196 degrees Celsius. Marlys Houck, a researcher with the zoo, was quoted as saying that “this first round of po‘ouli cells have been frozen with very good viability.” She continued: “Establishing a living cell line from bird tissue, especially from an older individual as in this case, is particularly challenging, making this accomplish ment even more remarkable. As the cells continue to grow, more vials will be frozen, and a small population of cells will be har vested so that the chromosomes can be analyzed.”

Sexing: One of several surprises associated with HR-2 was the discovery that the bird was a male. In the late 1990s, as an important stage in devising ways to encourage the po‘ouli to reproduce, knowing the sex of each of the three known birds became of paramount importance. Feathers from all three birds were sent to several labs in hopes of learning the birds’ gender. Eventually, the population was thought to consist of two females (HR-1 and HR-2), with HR-3 being the only male, although not all results agreed and even the lab whose work seemed most reliable was not prepared to guarantee its results. One of the chief impediments facing the researchers at tempting to determine the birds’ sex was a dearth of genetic material to use in the tests. Once HR-2 was caught, however, tests readily revealed the bird in hand was a male.

— Patricia Tummons

Volume 15, Number 9 March 2005