Habitat restoration aiding the recovery of the Maui Parrotbill
A project to protect and restore the habitat of the critically-endangered Maui Parrotbill is underway in Maui, Hawaii, ahead of moves to encourage repopulation of the species.
The Hawaiian Islands are the extinction capital of the world, having lost more bird species than anywhere else on earth. Similar to other oceanic islands, the arrival of humans in Hawaii, and the non-native animals, diseases, and plants brought with them, had devastating effects on naïve flora and fauna which continue today.
About 70% of the known bird species endemic to Hawaii have been lost since the arrival of Polynesians less than 1,000 years ago. Hunting, especially of flightless species, habitat destruction and degradation, non-native predators and non-native diseases all contributed to these losses.
Currently, climate change and non-native diseases present the greatest threat to the remaining species. Avian malaria is the most pernicious disease, but fortunately it and its vector, mosquitoes, are limited by cool temperatures and high elevation forests remain disease-free.
Climate change, however, is eroding these refuges. Almost all of the species that remain have undergone drastic population declines and range contractions.
One of the more critically endangered of these is the Maui Parrotbill (Pseudonestor xanthophrys), an insectivorous honeycreeper endemic to the island of Maui. Most of this species’ preferred habitat was converted to agriculture by Polynesians and destroyed by non-native ungulates brought by Europeans. Currently about 500 parrotbill are restricted to 40 sq km of high elevation disease free wet forest of the windward side of east Maui.
What does the Maui Parrotbill need to survive?
If this species is going to persist, the availability of suitable habitat needs to be increased
High quality, disease-free native habitat is the major factor limiting parrotbill, although its low fecundity complicates its recovery. Within existing suitable habitat, adults, with established home ranges, have high survival, with some being at least 15 years old.
However, young birds do not appear to be acquiring territories and have a low apparent survival rate. Territory mapping of banded adults suggests that there is insufficient habitat for young birds to establish territories. In addition, the area’s heavy rainfall results in low nest success suggesting that this habitat is suboptimal.
The fossil record and historical observations tell us that the species occupied drier habitats in the past and the species’ current range may be an artifact of past habitat destruction and the current distribution of disease. If this species is going to persist, the availability of suitable habitat needs to be increased and such an effort is currently underway.
Increasing habitat for native birds
A landscape scale fencing project has been initiated to protect the Nakula Natural Area Reserve and the Kahikinui Forest Reserve on the leeward side of east Maui. Once these areas are fenced, non-native ungulates will be removed and habitat restoration will be initiated. The Leeward Haleakala Watershed Restoration Partnership, a voluntary group of private and public landowners, is protecting adjacent habitat.
Thus, much of the high elevation area on leeward Haleakala is slated to be fenced and restored. Historically, this area supported mesic and dry forest communities, many dominated by koa (Acacia koa), which observations of early naturalists suggest was the preferred habitat of Maui Parrotbill.
Despite being severely degraded by non-native cattle and goats for well over a century, natural regeneration of some species is expected to occur once the animals are removed and active restoration of important parrotbill food plants as well as endangered species will be initiated.
Establishing new populations of Maui Parrotbill
Establishing a second population of Maui Parrotbill is a critical recovery action. Not only is it important to have an insurance population, but providing additional habitat will allow the population to grow. Furthermore, it is expected that the production of young parrotbill will increase in this drier habitat where winter storms are less frequent compared to the windward side of the island.
Translocating wild birds and releasing captivity-reared individuals will be used to establish this population. To maximize the success of establishing a new population, it is important to consider the genetic diversity of the birds (ie founders) translocated to establish the new populations and this is currently being assessed. This information will allow managers to translocate individuals representative of the species’ genetic diversity. This will reduce genetic drift and give the new population the genetic foundation to succeed. Reintroduction of Maui Parrotbill will begin within the next five years.
More information on Maui Parrotbill research and recovery efforts