BY SYDNEY ROSS SINGER – Here’s a trick question. Be careful before you answer. How many sheep must you kill to save one palila bird?
Before you answer, you need to know something about the palila bird, which is endangered and which most people never get to see.
The palila is a finch-billed species of honeycreeper, listed as endangered in 1967. It lives exclusively on the slopes of Mauna Kea, on the Big Island. Here are some palila facts:
The range of the palila is now limited to about 30 square kilometers, containing about 95% of the population. Loss of habitat to agriculture and ranching are primary causes of this bird’s decline.
Their diet mainly consists of the seeds of mamane trees, naio berries, and a special caterpillar that also eats mainly mamane seeds.
The caterpillars, which the palila requires for survival, are themselves under serious threat from parasitoid flies and wasps, some of which were introduced to Hawaii as biocontrol agents. These parasitoids lay eggs that feed on the caterpillars and destroy them. The caterpillars are also killed by yellow jackets and ants. Palila cannot live where there are none of these mamane caterpillars.
Predators of palila eggs and hatchlings include feral cats, rats, and mongooses.
Bird diseases carried by mosquitoes, such as pox and malaria, limit the palila to high elevations where the mosquitoes do not go.
Recovery of mamane forests through ungulate control (sheep, goats, cattle) has not resulted in recovery of the birds. The palila does not seem to like eating from the young mamane trees.
The seeds of the mamane are toxic to most animals, containing an alkaloid. The palila is immune to this poison, as is the caterpillar. However, palila prefer some mamane trees to others, as do the caterpillars, and the reason for this is unknown.
Perhaps the greatest immediate threat to palila habitat is fire, which is made more likely by alien grasses and weeds and climate change that brings more droughts.
In short, here is a specialist seed and caterpillar eating bird, limited in range to elevations above mosquito territory, predated upon by rats, cats, and mongooses. The fate of this bird is connected to the fate of the caterpillar on which it feeds, and the caterpillar is having survival troubles of its own. And all the conservation efforts to save this bird and regenerate its environment can all go up in smoke with the next fire, made more likely by the dry grasses now overgrowing palila habitat as a result of reduced sheep and reduced rainfall.
In the real world, the complex web of life, along with the powerful impact of climate change, makes the palila problem a perplexing puzzle. However, in the legal world, the solution included the court ordered eradication of feral sheep, Mouflon sheep, and goats from the area to allow mamane forests to regenerate. This court order was in response to lawsuits brought by the Sierra Club and Audubon Society against the Hawaii DLNR to protect the critical habitat in which the palila could live. Well intentioned efforts for sure, but now, thirty years later, we must ask if the slaughter of tens of thousands of sheep and goats have helped the palila. (Goats are now eradicated from the area.)
The answer seems to be no. Palila numbers fluctuate independently of sheep numbers and change with drought and availability of mamane and caterpillars. Recovery of the mamane forest seems only a small part of the puzzle, since palila and caterpillars don’t seem to like all mamane trees equally.
How did the sheep get there in the first place? They were introduced in 1793 for food. Later, King Kamehameha encouraged these animals as a food source for the people, and hunters today still follow a tradition of using these sheep as part of a sustainable, self-sufficient lifestyle.
In fact, the DLNR is mandated to encourage hunting and introduce food species to the wild, a mandate that stems from the time when people realized that living in Hawaii requires self-sufficiency and sustainability since we are an island and may have to rely on ourselves for our food. Mouflon sheep, endangered in their native areas of Sardinia and Corsica, were introduced as late as the 1950’s, and have interbred with feral sheep to produce our own, unique breed of Hawaiian wild sheep.
Ironically, the greatest defenders of the wild sheep are the hunters. And here is another piece of the palila puzzle. Sheep need to be controlled and managed by predators, and hunters serve that purpose. When sheep numbers are too high, overgrazing can destroy plants. However, when sheep numbers are too low, grasses and weeds take over, increasing fire damage. The key concept is balance.
Nature finds a balance, and humans are part of that balance. Hunters, however, are not eradicators. Eradication means no more sheep, no more food, and no more hunting. And since sheep have been part of the environment now for over 200 years, their loss has some negative consequences, such as reduced weed control and associated increased fire risk. Keep in mind that sheep provide important environmental services. They are weed eaters. This makes them fire preventers. And fire is the worst thing of all.
As a result of the court order, eradication efforts include fencing of the area to limit sheep movement and facilitate sheep slaughter from helicopters. Hundreds of sheep are massacred at a time, littering the area with dead bodies. Over the past 30 years, more than 40,000 sheep have been massacred. Most of the dead carcasses are left to rot, with a few airlifted to a small group of people allowed to take them home for food. It would be a vulture’s paradise, if we had vultures in Hawaii. Instead, no doubt, the rats and mongooses and flies and ants that threaten the palila have a feast, courtesy of the government.
You can get rid of the sheep, but what about the increased fire risk that will result? You can get rid of the cats, (which they are working on) but what about the increase in rats? And then you have to worry about the caterpillars, since the palila is as dependent upon them as on the mamane tree itself.
Meanwhile, another threat to the palila is going unmentioned. It is from scientists themselves. Birds are caught from the wild and fit with radios to follow their movements, and are released in areas where the birds do not seem to want to be, despite the presence of mamane trees. All this research takes its toll on animals. Scientists are allowed to accidentally kill palila so long as it is part of an experiment whose ultimate purpose is to save palila. This makes scientists a palila problem, too.
Is there a solution? The goal of recreating palila habitat is clearly too complex, biologically and politically. You will have to eradicate every plant, insect, animal, and microbe that was not here before western contact. All the wild sheep would be destroyed, depriving the people of a natural resource that has been here for centuries.
You will have to trap or poison all the feral cats and rats and mongooses. You will have to eradicate the yellow jackets and ants, and somehow eliminate all the parasitoid wasps that threaten the caterpillars on which the palila feeds. You will have to limit cattle ranching and development along the Mauna Kea slopes. You will have to find out why the palila and the caterpillars prefer some mamane to others. And you will have to pray for rain, since one fire can end the whole thing.
Naturally, the easiest thing to do is to continue to shoot sheep from helicopters. After thirty years, sheep slaughter on Mauna Kea has become an institution, even if it is not helping the palila, whose numbers continue to decline despite all the bloodshed.
If one thing is clear, it’s that it is time to re-examine the eradication of all the sheep as a method of saving the palila. This carnage is wasteful, cruel, and increases fire risk. It is not working. It is violating the mandate to protect the palila, and to stock our island with wild food and wildlife.
So, getting back to the question that started this discussion, how many sheep must you kill to save one palila bird? The answer is that 40,000 is not enough, and killing the sheep may actually harm the palila.
We need to manage our natural resources, not eradicate them. Eradication is a dead end, and in the end we may lose both the palila and these unique, wild sheep, a legacy from even before King Kamehameha.
If you would like to help please sign a petition that asks President Obama and Governor Abercrombie to call for a moratorium on the sheep eradication and renewed research into better ways to protect the palila that really work. Thirty years of slaughter is enough.
To see the petition, go here: https://www.change.org/petitions/call-for-moratorium-on-hawaiis-wild-sheep-eradication