Oma’o  (Myadestes obscurus)

The oma’o occurs in just a few localities on one island, and thus is vulnerable to threats, despite healthy population numbers at present (5). In the past, habitat clearance for firewood, timber, agriculture and pasture has resulted in the species inhabiting only 25 to 30 percent of its former range (2). Its current distribution has also been heavily influenced by the presence of introduced mosquitoes, which spread avian malaria and avian pox (2) (5). However, there is evidence that oma’o have developed some resistance to the current strains of these diseases, as this species persists, whilst others have disappeared. Nevertheless, the oma’o still occurs at greater densities above 1,500 meters, where mosquitoes are less common (4). A potential future threat is the introduction of a cold-tolerant mosquito, along with new avian diseases (4). Further pressure on the oma’o comes from the spread of feral predatory mammals, such as rats and cats, into upland forests. In addition, the degradation of habitat caused by feral ungulates, particularly pigs, is likely to have caused the destruction of native plants important to the oma’o’s diet (2) (3).

The oma’o occurs in several well-managed protected areas, such as the Hawaii Volcanoes National Park (6), and the Hakalau Forest National Wildlife Refuge (7). This follows efforts during the 1980s and 1990s to purchase, protect and manage remaining areas of natural forest above 1,500 meters (2) (4). There have also been efforts to control and fence out feral pigs, goats, cattle and sheep, but there has not been any evidence yet that this has resulted in an increase in bird numbers (4). The presence of rats continues to be a significant problem to the oma’o and other native Hawaiian birds, and thus the implementation of a rat control program has been proposed (3) (5).