Native Honeycreepers Evolved Over 6 Million Years. Now They’re Barely Hanging On.
As mosquitos move into higher elevations, they kill off endemic species. A UH Hilo specialist is working to save them.
Populations of several native birds have crashed in the past 20 years. In this Q&A, UH Hilo ecology professor Patrick Hart describes what’s gone wrong and how we can save these iconic birds.
Hawai’i has many endangered birds. Which species are you most concerned about?
There is unfortunately a whole bunch of species we’re worried about. The most endangered is the ‘akikiki, or Kaua‘i creeper. It’s down to fewer than a hundred individual birds on the Alaka‘i Plateau on Kaua‘i.
The kiwikiu, also known as the Maui parrotbill, has approximately 100 to 150 birds left. The ‘akeke‘e on Kaua‘i doesn’t have many more individuals than the ‘akikiki, about 200 to 300.
All of these birds, especially the ‘aki-kiki and ‘akeke‘e, were doing really well but their populations have crashed just over the last 20 years.
These birds are all considered to be honeycreepers. They’re native Hawaiian birds and have evolved here over 6 million years – longer than most plants and animals, so they are truly native Hawaiian species.
To lose them is a very big deal in a lot of ways. Native Hawaiian birds are important culturally to Hawaiians. Bird feathers were used to create a lot of very valuable pieces of art, like the feathered capes the ali‘i wore. The bird catchers, kia manu, were valued members of society because they would catch these birds and get their valuable feathers.
So the loss of these birds is devastating. It’s depressing because they’ve been here for so long and to be losing them now, when we have the tools to stop it, is very much a shame.
What’s Causing This?
There are a lot of reasons. Ever since humans arrived, some species of birds have been declining. Humans hunted the ones that didn’t fly very well.
Recently, we’ve introduced a lot of predators like cats, mongoose and rats, who prey on nesting birds.
Mosquitoes are probably the biggest problem. Mosquitoes transmit avian malaria to the birds. There were no mosquitoes in Hawai‘i until the early 1800s (when the Islands opened to trans-Pacific trade). Humans brought them accidentally. One species, the southern house mosquito, transmits avian malaria to our native birds, which evolved in the absence of mosquitoes and lost all their resistance to mosquito-transmitted diseases.
A single mosquito bite is enough to kill several types of land birds.
Can Native Hawaiian Birds Make a Comeback?
That’s our goal. If we didn’t have hope, we wouldn’t be doing what we do.
We need to reduce mosquito populations across the landscape and reduce the number of pigs in the forest because they make breeding habitats for mosquitoes.
We can also reduce mosquitoes through different sterile insect techniques, where we sterilize mosquitoes and release them into the forest, and they breed with wild mosquitoes and cause them to be sterile. If you can release enough of them in the forest, it can drive mosquito populations down so the native birds can come back.
We’re seeing other birds increase in numbers due to conservation efforts – the nēnē for example. Breeding and release programs have moved them from an endangered species to a threatened species.
How Can Locals Help?
Support programs that are in place. A lot of it is public education and outreach, just getting more people to understand that we have this problem and there are things that we can do about it that we’re not doing, and part of it is because there’s not enough public support.
I think supporting things like mosquito control efforts, when that comes up on the ballot, is really important and programs to reduce the impact of cats where seabirds are nesting, because cats eat all the baby seabirds.
There are other little things, like making sure you don’t track ROD (rapid ‘ōhi‘a death) into the forest by spraying your boots with alcohol beforehand, reducing places that mosquitoes breed by not leaving open containers out, and supporting fencing programs to keep pigs out of certain areas. Mosquitoes follow pigs into the forest, then they bite the birds.
Would More Pig Hunting Benefit the Conservation of Native Birds?
Yes, I think increasing hunting would be great. That would help a lot.
Do Nonnative Birds Affect the Native Birds?
Some of them play really well with the ecosystem and with native birds. Birds like the Java sparrow don’t have a big impact on the environment, but some do.
The biggest problems are the ones that eat fruit and spread the fruits of invasive plant species into the forests. Certain parrots, like the rose-ringed parakeets on Kaua‘i, have become a big problem because they eat people’s fruit and spread seeds of fruit that invades the native forests.
Will Climate Change Affect the Native Bird Population?
One of the worst examples is the way mosquitoes are increasing in elevation with global warming. Right now, mosquitoes are only in the lowland habitat up to about 4,500 feet. All the forest above that doesn’t have many mosquitoes so the birds can live there.
But with global warming, the mosquitoes are moving up in elevation to the remaining habitat that’s being occupied by the birds. That’s why the birds on Kaua‘i are declining so fast. The mosquitoes are in the Alaka‘i Swamp when they weren’t up there 20 years ago. That’s having a massive impact on our native birds.
There’s a lot of people across the state working to reduce that by planting trees at higher elevations so the birds can keep moving up. On Maui and the Big Island, birds can live higher up, but the forest has been deforested higher for ranching. So the birds are sandwiched in between the rising mosquitoes and no trees to live in. The space that they can live in is getting smaller and smaller.
We need to do all we can to turn that around through landscape-scale mosquito control or through planting forests at higher elevations.
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