Creating a backup population in combination with vaccination against West Nile fever will significantly reduce the risk of extinction of island shrub jays, a rare species of corvids, who lives on the island of Santa Cruz off the coast of California. Right now the island is free from dangerous infection, which has already brought populations of many North American birds, however, as global climate change, the probability of its penetration is growing here. The simulation results presented in the article for the journal Diversity and Distributions.
From the rapid spread of infections affects not only people, but also many wild animals. For example, about twenty years ago in North America from the Old world entered the West Nile virus. His main victims were local birds, whose immune system was not adapted to the alien infection. As a result, the number of a number of species has decreased markedly. For example, American crows (Corvus brachyrhynchos) because of a virus lost almost half of the population.
Ornithologists fear that the spread of West Nile fever can lead to extinction of some rare species. Of particular concern to them is the fate of island shrub jays (Aphelocoma insularis) — the brightly colored bird of the family of corvids (Corvidae). Its population is only about 1700 species, and confined to the island of Santa Cruz, which is part of the group of channel Islands off the coast of California.
In our days on Santa Cruz, no West Nile, so right now the infected island jays are not in danger. This is partly due to the fact that the average temperature here rarely exceeds 23 degrees Celsius — the threshold, after which the outbreak of infection is particularly likely. However, as global climate change conditions become more suitable for the spread of the disease from the mainland. It makes ornithologists today to prepare for the possible entry of the virus in Santa Cruz.
A team of researchers led by Victoria Becker (Victoria J. Bakker) of the University of Montana decided to find out whether it is possible to provide rare birds with protection, resettling part of the population on the neighbouring island of Santa Rosa. Once the blue jays, and lived on it, but at the end of the XIX century became extinct because of the disappearance of vegetation under the onslaught of imported cattle.
Santa Rosa is located farther from the California coast, so its climate is cooler. This means that the risk of outbreaks of West Nile fever here below. Creating in Santa Rosa “insurance” population of jays, an ornithologist would give a mean chance of survival even in the case that the virus will penetrate into Santa Cruz.
Comparing the availability of required habitat on both Islands, the authors came to the conclusion that Santa Rosa could become home to 453 species and 129 breeding pairs. For comparison, the environmental capacity of Santa Cruz is 515 breeding pairs. The average temperature in Santa Rosa never exceeds 23 degrees Celsius, which is below the required threshold of virus.
The mathematical model predicted that under current conditions the risk of extinction of island birds for 25 years a small. More frequent droughts and the penetration of West Nile fever have increased it to 22 percent. However, if the calculations were safety introduced population on Santa Rosa, it was significantly reduced even when the virus on both Islands. An additional factor of protection could be vaccination as Santa Cruz and Santa Rosa.
The authors recommend to use for the salvation of the island jays hybrid approach combining both vaccinated individuals and the backing of the population. This will not only increase the chances of species survival, but will also help the ecosystems of the island of Santa Rosa. Introduced herbivores destroyed here less than ten years ago, so flora is just beginning to recover. Jays, well-known distributors of seeds, could accelerate this process. This, in turn, will increase their own habitat.
On the Pacific island of Rota save another rare species of corvids — the GUAM crow (Corvus kubaryi). He suffers greatly from habitat destruction and invasive species. A few years ago started a project to reintroduce the hand-reared ravens in their natural habitat.
Sergey Knee High