The Battle of Midway is Still Raging...Among Invasive Plant Species

© Jaymi Heimbuch

There is a battle raging on Midway Atoll, but it doesn't involve the Navy. This time, it involves the US Fish and Wildlife Services and a lot of pairs of gardening gloves.

For decades, the US Navy and now the USFWS have been struggling to eradicate the invasive species brought to the atoll, from plants to animal species like rats. A massive rat eradication effort took place in the 1990s and was successful -- getting rid of the egg-eating pests brought back burrowing seabird numbers. However, there is still far more work to be done and the main focus are plants wreaking as much havoc as the rats once did.

On Sand Island, the island still used by people, there are over 240 plant species. The original island only had about 37 plant species. That means most everything on the island has been introduced! While there are many types that don't pose a significant problem to the health of the habitat, there are two species that are especially visible, especially troublesome, and especially hard to get rid of.

Exiling Verbesina

Verbesina is an invasive plant that causes a whole lot of problems. As I've stated before, think of the most pesky plant you've ever had to deal with -- a weed that never seemed to go away, that caused a host of problems in your garden, and if you could blow it up off the face of the planet, you would. That's what verbesina is to Midway.

© Jaymi Heimbuch

It may look like a lovely yellow flower, but it grows up to eight feet tall, choking up areas of land so that albatross can't nest or easily take off or land from flight. It blocks wind flow so that the nest sites near verbesina are much hotter which can cause the albatross chicks to overheat. The roots break up the soil which collapses the burrows of Bonin Petrels and the nests of other burrowing birds. And the plant blocks out light and soaks up water so that native plants can't establish themselves. That's why major efforts are taking place to finally rid the atoll of this species -- though it will be years before the plant finally disappears.

The Oceanic Society, a non-profit organization that leads tours to the group and which sponsored a portion of my trip to Midway, also focuses some of their volunteer efforts on helping USFWS knock down some verbesina. Over the years, participants with the tour have helped knock out some of the verbesina. Photographer Rebecca Jackrel who was on the tour with me pointed to a dune that looked like pristine habitat, noting that on a previous tour she had helped clear the beautiful white-sand dune of the invasive weed. Now, several years later, the dune is still clear of the weeds and looks wonderful.

In fact, before and after photos of the efforts show what incredible progress has been made:

Forest & Kim/CC BY 2.0

Forest & Kim/CC BY 2.0

Removing Ironwood Trees

Ironwood trees are another serious problem for the bird species of Midway. The trees were originally brought to the atoll to act as windbreaks. They are salt tolerant and grow quickly, which is exactly what the humans wanted -- but it's anything but helpful for the birds, especially birds that have a six-foot wingspan. Albatorss get caught in the trees and can't free themselves. If they don't die on impact, they die soon after getting tangled in the branches.

© Jaymi Heimbuch

There are large stands of ironwood trees all over the island. It might seem like a no-brainer: just cut them down and be done with it. But this is no easy task, and not all that practical.

© Jaymi Heimbuch

There is a reason the trees are called ironwood tree: their wood is extremely hard and chopping them down is serious work. And when you're on an atoll in the middle of the Pacific ocean, getting heavy machinery out to cut them down is an expensive proposition. Say USFWS were to have all the machinery they need at their disposal -- they still need workers to help clear the trees. On an island where there are less than 80 people, most of which are not USFWS staff but are contracted to help run the island's services, getting workers who are able to deal with the heavy labor of cutting down these trees is also a significant challenge. And what do you do with the trees once cut? Hauling them away is again an expensive option.

All said, there isn't the money or manpower to take these trees down in one fell swoop. But the USFWS is chipping away at the problem a little at a time. As there is equipment, laborers, time, and space to pile up the trees and allow them to decay, the trees are slowly being removed from the atoll. Not all the trees will be removed. The fact is, they make some areas a lot more pleasant for humans by providing shade and windbreaks, and so some will stay. But the trees in the areas most needed as habitat for nesting albatross will be removed.

© Jaymi Heimbuch

Bringing Back Native Plants

The most noteworthy part of habitat restoration happening on Midway today isn't weeding, but planting. I was able to witness this part of their efforts first hand during a volunteer effort with the Oceanic Society.

Midway's Greg Schubert, the Biological Technician with USFWS, is hard at work restoring native plant species to the atoll's islands. Much of this effort takes place in the greenhouse on Sand Island where native grasses and plants are started, and along roadsides where an effort to restore bunch grass is underway. The bunch grass not only acts as helpful habitat for the birds, but will also help keep down the spread of invasive plants.

© Jaymi Heimbuch

Schubert noticed that the spread of invasive plants was caused in large part from people. The seeds were picked up on people's shoes and on the tires of bikes and golf carts used around the island, and carried to other locations. If the seeds transported alongside roads could be contained then more progress would be made. The bunch grass helps accomplish this by catching the seeds from other plants and keeping them from blowing in to areas where they could take root. The bunch grass grows thick enough that seeds can't easily sprout within it. So it's a winning strategy.

© Jaymi Heimbuch

By practicing "out with the new, in with the old" the habitat of Midway is slowly starting to look more like it once did before humans let non-native species run amok. There is a reason Sand Island is named such -- it used to be all sand, naupaca (pictured below), and a handful of native grasses and other plants. While Sand and Eastern islands will probably never look like they did even just over a century ago, they will certainly look closer to it and that is a big boon for the birds.

The habitat restoration efforts have already seen big successes in boosting numbers of nesting seabirds, and it is only a matter of time, a few worn pairs of gloves, and the efforts of some very dedicated people.

© Jaymi Heimbuch

If you'd like to take part in an expedition to Midway or other atolls, check out the trips offered by the conservation group Oceanic Society. It's ecotourism at its best!

Tags: Conservation | Ecology | Midway

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