Last month, The Wildlife Society, a national association made up mostly of specialists in the area of wildlife research and management, held its annual convention at the Waikoloa resort, on the Big Island.<\/p>\n
Over the four days of discussions and symposia connected with the meeting, some of the most respected names in Hawai`i biology took to the podium, providing a largely mainland audience with their perspectives on what it will take to conserve and restore Hawai`i\u2019s unique fauna \u2013 birds, of course, but also monk seals and humpback whales, bats, snails, and other invertebrates.<\/p>\n
During one of the two plenary sessions, William Aila, head of the Department of Land and Natural Resources, made a moving plea for the need to control game animals, taking note of Governor Abercrombie\u2019s recent watershed initiative. \u201cWe have to control ungulates. Fencing and removal of ungulates, especially in watersheds, is a major part of our plan going forward,\u201d Aila said. \u201cWe have made a conscious decision that in priority watersheds, we are going to double the amount of fencing and protection.\u201d<\/p>\n
Fencing, removal of introduced game species, and restoration of habitat for native wildlife was an undercurrent in nearly all of the talks by Hawai`i presenters. In a few cases, their reports on recent research broke new ground. For the most part, they simply tried to carry the message of Hawai`i\u2019s dire straits to an audience generally unaware of its problems. And they did so often with an eloquence and strength not usually found in dry academic discussions.<\/p>\n
We present highlights here:<\/p>\n
* * *<\/b><\/p>\n
Lowland Bird Populations May Be Developing Malaria Tolerance<\/b><\/p>\n
Avian malaria, one of the scourges of Hawaiian forest birds, is a major reason why they are found so rarely in lowland forests. For years, it was generally thought that birds could only survive above the so-called \u201cmosquito line\u201d \u2013 elevations above which mosquitoes, which carry the disease, do not thrive.<\/p>\n
But a few years ago, in connection with a major survey of biological complexity in the islands, Carter Atkinson and colleagues with the U. S. Geological Survey, Pacific Island Ecosystems Research Center were finding more Hawai`i `amakihi (Hemignathus virens virens<\/i>) at low elevations than at high sites. \u201cWe were amazed,\u201d Atkinson told a crowded meeting room at the annual conference of The Wildlife Society, held last month at Waikoloa.<\/p>\n
\u201cWe were capturing `amakihi at rates five times higher than the capture rates at high-elevation sites,\u201d he said. \u201cAlso, they had extremely high prevalences of malaria,\u201d reaching a rate of up to 90 percent at one site.<\/p>\n
He compared that to the mid-1990s, when no `amakihi were detected at any of the 90 stations surveyed in the Puna district of the Big Island. A decade later, 75 `amakihi were found at 37 of the stations \u2013 \u201ca significant increase in the numbers,\u201d he noted. \u201cSince then, we have evidence this population is expanding toward Hilo. There\u2019s been some change in the birds\u2019 ability to deal with malaria infections.\u201d<\/p>\n
But the good news does not end with `amakihi. Researchers are finding that another one of the more common forest birds, the `apapane (Himatone sanguinea<\/i>), is present at lower elevations on O`ahu and Moloka`i, where it also shows a high prevalence of malarial infection. In the Big Island districts of Puna and South Kona, the prevalence of malaria among `apapane can run as high as 100 percent among low-elevation populations of the bird.<\/p>\n
\u201cOn Kaua`i, the prevalence of malaria is as high as 40 percent\u201d among `amakihi.<\/p>\n
\u201c`Elepaio [Chasiempis sandwichensis<\/i>] may also be showing similar disease patterns,\u201d Atkinson said, \u201cwith a high prevalence of infections.\u201d<\/p>\n
\u201cIt\u2019s good news about the more common species,\u201d he said, but for rarer species, \u201cit\u2019s more problematic.\u201d\u00a0<\/p>\n
\u201cA lot of what we\u2019re seeing may depend on genetic diversity,\u201d he added. \u201cBut do these fewer birds still have sufficient genetic diversity?\u201d<\/p>\n
To confirm the `amakihi\u2019s tolerance to malaria, Atkinson and colleagues exposed uninfected birds from both high- and low-elevation sites to malaria. \u201cThere was a dramatic difference,\u201d he said. \u201cWe lost two low-elevation birds, but over half of the high-elevation birds died.\u201d Other differences emerged as well. The high-elevation birds exposed to malaria suffered more from depressed appetite than did those from low elevations, which consumed as much food as birds in the healthy control population. Also, he said, the physiological effects of disease were much less severe in the low-elevation group.<\/p>\n
\u201cThe results support the idea that low-elevation birds have some physiological tolerance to malaria,\u201d he said, related to an increased ability to survive the disease.<\/p>\n
\u201cDisease tolerance may have appeared in lower Puna,\u201d he continued, \u201cbecause of abundant low-elevation habitat and high selective pressure by the parasite. There were also large, connected source populations across an elevational gradient, plus there is very high genetic diversity in `amakihi.\u201d\u00a0<\/p>\n
Geneticists, he said, found the low-elevation birds were genetically distinct from their high-elevation counterparts. \u201cBut,\u201d he went on to say, \u201cwhen compared to museum specimens collected 100 years ago \u2013 there\u2019s only one way you can interpret this \u2013 those birds were always there in low numbers at these sites; they simply expanded from relic populations.\u201d Or, as Atkinson and his colleague Dennis LaPointe, also with USGS, wrote in a 2009 article in The Journal of Avian Medicine and Surgery,<\/i> \u201cthe recent resurgence of these birds originated from pockets of surviving individuals with some natural disease resistance, rather than recolonization of the lowlands by high-elevation birds.\u201d<\/p>\n
As to why the lower-elevation populations may have developed this resistance while those in the higher elevations did not, Atkinson and his colleagues put forward an explanation in their 2009 article: \u201cWith transmission occurring year-round at lower elevations, and low-elevation populations not being continually diluted by emigrating, highly susceptible juvenile birds from high elevations, it might be predicted that disease resistance would first appear here. This suggests that disease resistance may subsequently spread over the next few decades, with eventual recovery of mid-elevation populations of the more resistant species.\u201d<\/p>\n
And while that is good news for `amakihi, it may not be for those less common birds. \u201cThere is concern that threatened and endangered species may not have sufficient genetic variability to adapt to these diseases,\u201d they write.<\/p>\n
The question now for resource managers is whether it may be possible to undertake actions that will enhance the birds\u2019 disease tolerance.\u00a0<\/p>\n
Above all else, Atkinson said, \u201cwe have to preserve existing diversity, then manage habitats to maximize demographic variables, especially at lower elevations.\u201d In their article, Atkinson and LaPointe stress the importance of managing mid-level habitats to reduce mosquito breeding areas. \u201cFeral pigs and other ungulates can create larval habitat \u2026 and their removal through fencing and control programs may significantly reduce mosquito habitat, particularly on Kilauea and Mauna Loa Volcanoes \u2026 where volcanic soils are porous and streams and natural bodies of water are rare.\u201d<\/p>\n
In addition, they write, \u201cthere will likely be an important place for vaccines and chemotherapy for management of avian pox and malaria during translocation or release of captive birds or management of small populations of critically endangered forest birds,\u201d although such treatments are not now available.<\/p>\n
* * *<\/b><\/p>\n
The \u2018Worst Vector\u2019 and Its Partner<\/b><\/p>\n
Dennis LaPointe, an ecologist with the U.S. Geological Survey in Hawai`i, has been studying mosquitoes and avian malaria for years, and in his view, Culex quinquefasciatus,<\/i>
\nthe first mosquito to hit Hawai`i\u2019s shores, is \u201cthe worst vector of [avian] malaria in the world.\u201d<\/p>\n
But if the mosquito were here without pigs, chances are good that the overall health of Hawai`i\u2019s forest birds would be much improved. To cause the damage that avian malaria and avian pox have wrought, the mosquitos needed water.<\/p>\n
\u201cWater is key to the vector,\u201d LaPointe said, \u201cpolluted, organic-rich water.\u201d But on Mauna Loa, standing water is in short supply, what with the porous volcanic substrate and no streams or other bodies of water to speak of.<\/p>\n
Enter the pig. Not the small Polynesian pig, which Hawaiians brought with them when they colonized the islands and which, according to accounts of early visitors, rarely weighed more than 50 or 60 pounds. No, it required the much larger European pig, introduced in 1785 by Captain Cook and in multiple subsequent visits by any number of ship captains. As Quentin Tomich writes in his Mammals in Hawai`i,<\/i> \u201cThe old Polynesian type of Sus scrofa<\/i> has been absorbed or replaced by stocks of European origin.\u201d The result is that \u201cthe feral Hawaiian pig of today is typically like the Eurasian wild boar.\u201d<\/p>\n
\u201cPigs love the rainforest,\u201d LaPointe noted in his presentation to The Wildlife Society. \u201cThey\u2019re particularly fond of tree ferns, whose starchy core is a favorite food of pigs.\u201d The pigs knock down the ferns and root out hollows to reach the core, in the process creating cavities. Rain collects in the cavities, where mosquito larvae can mature.\u00a0<\/p>\n
What LaPointe and his colleagues set out to determine, in the early 2000s, was whether, absent the pigs, mosquitoes would find sufficient larval habitat to allow the malarial cycle to continue. Hunters defending their sport claim pigs alone aren\u2019t responsible for the standing water.<\/p>\n
\u201cSo we looked at the disease across a broad landscape of windward [eastern] Mauna Loa,\u201d he said. They set up study sites in wet, closed-canopy `ohi`a forests, where both pigs and tree ferns typically occur.<\/p>\n
\u201cWe found a direct relationship between the relative abundance of pigs and the abundance of tree fern cavities,\u201d he said. Where pigs are controlled, he continued, \u201cthere were no tree fern cavities\u2026 Tree fern cavities are not the result of natural decay or rodent feeding.\u201d<\/p>\n
In addition, his team began monitoring mosquito populations by trapping. \u201cThe highest capture rates,\u201d he said, were found at Cooper Center, in Volcano Village. There, he said, \u201cpig-created tree fern cavities are the dominant available larval mosquito habitat.\u201d<\/p>\n
Until the pigs are gone or, at least, their numbers are significantly reduced, Hawai`i forest birds will continue to be at risk for disease. According to LaPointe, \u201cyou have to depress current pig abundance by at least 80 percent\u201d before the birds are released from the impact of disease.<\/p>\n
There could be one other factor at work, however. LaPointe noted that in 2002, the mosquito Aedes japonicus <\/i>arrived on Hawai`i island and is now in all the same areas as Culex. Ae. Japonicus<\/i> \u201ccannot vector avian malaria,\u201d LaPointe said. \u201cWe don\u2019t know if it\u2019s driving the abundance of Culex<\/i> down, but it would sure be nice to hope so.\u201d<\/p>\n
Everything has its downside, though. While an increase in Aedes japonicus<\/i> might knock back Culex quinquefasciatus, Ae. Japonicus<\/i> is itself a possible vector of avipoxvirus, Japanese encephalitis, and West Nile virus, which can cause disease in both humans and birds.<\/p>\n
* * *<\/b><\/p>\n
`Elepaio Moving Up in the World<\/b><\/p>\n
Eric VanderWerf has been studying the O`ahu `elepaio for years and has watched its numbers decline dramatically in recent years. Since 1970, he told members of The Wildlife Society, it has seen a 75 percent decline in its range, which is now highly fragmented. Its overall population has declined as well, and is now thought to number no more than around 1,500 birds.<\/p>\n
One of the greatest threats to the `elepaio is the black rat, which can take the birds from their nests at all life stages: eggs, juveniles, and incubating females. For this reason, he said, rat control is a primary tool in protecting `elepaio populations from further decline. With control, the population growth rate is positive at 1.1 (with 1 equal to a stable population). Without it, the growth rate is below 1.<\/p>\n
But, he continued, \u201conly a fraction of the remaining populations are being managed\u201d with efforts to control the rats.\u00a0<\/p>\n
One of the reasons why `elepaio are so vulnerable, VanderWerf explained, was the fact that their nests tend to be low to the ground.\u00a0<\/p>\n
\u201cBut nowadays, their nests seem to be higher,\u201d he said. He compiled data on recent nest heights, \u201cand sure enough,\u201d he said, \u201cthe average nest height is rising.\u201d From an average of eight meters in 1996 it has soared to about 12 meters in more recent years. \u201c`Elepaio are choosing larger trees,\u201d he said.<\/p>\n
There were two possible mechanisms to explain the change, he said: individual birds are learning that a higher nest is better and are adjusting nest height accordingly; or nest height is evolving through natural selection.<\/p>\n
VanderWerf tested the first hypothesis by looking at the nest height of individual birds and found nothing to suggest that the birds were actually learning that higher nests were better.<\/p>\n
He then looked at the success rates of lower nests and found that those lower than three meters \u201calways failed or were abandoned,\u201d he said.<\/p>\n
Over time, the proportion of lower nests (below three meters) was decreasing, while nest success increased.<\/p>\n
The most likely conclusion, VanderWerf said, is that nest height among `elepaio is evolving through natural selection.<\/p>\n
How high will it go?<\/p>\n
Most nests below three meters, VanderWerf noted, are being eliminated \u2013 suggesting that this is about as high as rats go. \u201cThe average height probably will not get much higher than it is right now,\u201d he said.<\/p>\n
* * *<\/b><\/p>\n
Forests as Fodder<\/b><\/p>\n
Sheila Conant\u2019s sadness and indignation were palpable. In an overview of the dire situation that Hawai`i\u2019s native plants and animals are facing, Conant, an expert in the subject of endangered birds, talked about her personal experience: \u201cI\u2019ve seen living members of seven bird species now extinct,\u201d she noted. \u201cAnd I\u2019m not yet 100 years old!\u201d The line drew a laugh from the audience, but there was not much other humor in her talk to The Wildlife Society.<\/p>\n
The examples of adaptive radiation found in Hawai`i \u201care unsurpassed,\u201d she said \u2013 and are found in all manner of creatures and plants. \u201cThe silversword alliance \u2013 there are more than 30 different species. Spectacular plants,\u201d she told the crowd.<\/p>\n
\u201cHawaiian tree snails \u2013 just 14 of 40 Achatinella<\/i> survive. They\u2019re going down rapidly because of introduced predators and other reasons.\u201d\u00a0<\/p>\n
She then gave the example of Hawai`i\u2019s hyposmocoma moths: \u201cThey\u2019re not as spectacular as our Drosophila [picture-wing flies], but there are over 350 species known, with more being found all the time.\u201d They are also one of the few moths that are \u201cscuba divers,\u201d going underwater to pursue prey. \u201cOnly half a percent of all Lepidoptera have an aquatic stage,\u201d she said.<\/p>\n
After a recital of the flora and fauna that help make Hawai`i so special, Conant went on to discuss the reasons for their decline, citing habitat loss due to human activities, invasive predators as well as disease, ecosystem transformation by ungulates, and introduced plants that, while mild-mannered in their home range, quickly become invasive weeds in Hawai`i\u2019s hospitable climate.<\/p>\n
Of predators, she said, \u201cferal cats are probably the worst thing we\u2019ve got. They\u2019re very difficult to control, and it\u2019s politically a very sensitive issue. They\u2019re doing a great deal of damage to petrels on this [Hawai`i] island and on Lana`i. I don\u2019t even think about mongoose anymore because I see so many feral
\ncats. We need to address the issue in a suitable way.\u201d<\/p>\n
The brown tree snake, which has caused the extinction of many native birds on Guam, is another potential predator that keeps Conant up at night: \u201cIf we get this, it is just a matter of time before we lose all our small birds.\u201d<\/p>\n
Conant then addressed the subject of feral ungulates. \u201cOur ecosystems are being transformed by feral ungulates and alien game species.\u201d<\/p>\n
\u201cHawai`i,\u201d she continued, \u201cis feeding its native forests to escaped barnyard animals\u201d \u2013 pigs, sheep, and goats \u2013 \u201cand axis deer\u2026 Protected by bag limits and hunting seasons, they are managed to provide recreational and limited subsistence hunting for less than one percent of the state\u2019s population.\u201d<\/p>\n
Such practices \u201cprofoundly compromise Hawai`i\u2019s watersheds \u2013 our only source of drinking water and irrigation for our crops, and the last remaining habitat for countless species of unique plants and animals.\u201d<\/p>\n
\u201cWe know what to do,\u201d she concluded. \u201cLet\u2019s go out there and do it.\u201d<\/p>\n
* * *<\/b><\/p>\n
\u2018Funding Bias\u2019 Hurts Hawai`i Birds<\/b><\/p>\n
A frequently heard complaint from many members of Hawai`i\u2019s conservation community is that the state, which has such a high percentage of endangered species in the United States, receives such a small share of federal funding for endangered species management and recovery. George Wallace, a vice president of the American Bird Conservancy, elaborated on some of the reasons for the vast abyss between needs and resources.<\/p>\n
Hawai`i, Wallace pointed out, has 31 extant species of endangered birds \u2013 roughly 70 percent of all endangered bird species in the United States. Yet the average expenditure per species from 2002 to 2006 was 16 percent of what was spent on endangered bird species on the U.S. mainland. (If the enormously expensive captive propagation program for the `alala is not included, the per-species average expenditures drop down to 10 percent of the mainland per-species expenditures.)<\/p>\n
\u201cWhy is there such a funding bias?\u201d Wallace asked.<\/p>\n
There\u2019s the problem of Hawai`i\u2019s remoteness from the mainland and the lack of awareness of the plight of its birds \u2013 both here in Hawai`i as well as elsewhere, he noted.<\/p>\n
Wallace also cited the lack of \u201cconflict species,\u201d where high stakes bring public attention to the endangered animals \u2013 such as the spotted owl in the Pacific Northwest. These species, he said, get funding precisely because they generate conflict and much publicity. \u201cIt ties the Fish and Wildlife Service up in knots,\u201d he said, \u201cand draws a lot of funding and resources\u201d to these species.<\/p>\n
Another factor is the limited tax base in Hawai`i. Its relatively small population means that federal funding allocation formulas based on census counts put the state at a distinct disadvantage, Wallace noted.<\/p>\n
Also there is the fact that Hawai`i shares borders with no other state, Wallace pointed out. Elsewhere, multiple states might cooperate to address common problems. In Hawai`i, that just doesn\u2019t work.<\/p>\n
\u201cThe pattern is, the highest-funded species tend to be charismatic conflict species, from large states and large ranges,\u201d Wallace said. \u201cUnderfunded species tend to be island species, or from small states with small ranges.\u201d<\/p>\n
The upshot , he said, is \u201ca few taxa receive most of the funding.\u201d<\/p>\n
Wallace then presented some estimates on what recovery of Hawaiian birds might cost over the next 10 years. Fencing, eradication of ungulates, and weed control needed for forest-bird recovery will require an initial expenditure of $578 million, with upkeep costs of $32 million a year. Add in waterbirds and seabirds, and the total investment costs rises to between almost $800 million and $1 billion.<\/p>\n
\u201cWe need to set our sights on this,\u201d he said. \u201cThere\u2019s too much at stake not to. We have to keep reinforcing the message that we\u2019ve already invested a tremendous amount and we need to protect those investments.\u201d<\/p>\n
While the amount may have prompted some in the audience to gasp, Wallace pointed out that the amount is reasonable, even modest, in light of expenditures for similar recovery efforts undertaken elsewhere. In Chesapeake Bay, for example, federal recovery funds alone came to more than $1 billion over the span of a decade, he said. In the Great Lakes region, $5 billion was spent over 10 years, while in the Florida Everglades, $3.9 billion was spent over 30 years.<\/p>\n
\u201cHawai`i\u2019s birds need a national priority restoration initiative, and we need it now,\u201d he concluded.<\/p>\n
Patricia Tummons<\/p>\n
Volume 22, Number 6 — December 2011<\/p>\n","protected":false},"excerpt":{"rendered":"
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