Maui Invasive Species Committee (MISC)

  • A A A
  • Home
  • Careers at MISC
  • Report a Pest
    • Statewide Pest Hotline
    • Coqui Frog
    • Little Fire Ants
    • MISC Target Pests
  • About Us
    • Who We Are
    • Partners
    • Committee Meetings and Minutes
    • Strategic Plan
    • Contact Us
  • Our Work
    • LFA Detector Dog Program
    • Mālama i ka ʻĀina Award
    • Coqui Frog Control Program
    • Invasive Species Articles
    • Press Releases
    • Technical and Scientific Publications
  • MISC Target Pests
    • Coconut Rhinoceros Beetle
    • Red-Vented Bulbul
    • Rapid ʻŌhiʻa Death
    • Little Fire Ant
    • Coqui Frog
    • Miconia
    • Pampas Grass
    • Ivy Gourd
    • Blessed Milk Thistle
    • Fountain Grass
    • Mullein
    • Rubber vine
  • Get Involved!
    • Community Coqui Control Program
      • Make Your Yard Un-Friendly to Coqui Frogs
      • Community Coqui Control Code of Conduct
      • Effects of citric acid on the environment
      • Where are the coqui frogs?
    • Donate
    • Be Our Eyes and Ears
    • Survey for Little Fire Ants
    • Classroom Visits and Presentations
    • Workshops
  • MISC Target Species

Got Guano?

Posted on March 25, 2015 by Lissa Strohecker

This albatross colony on Midway Atoll is representative of what the historic density of seabirds may have been throughout Hawaiʻi. Declines in the seabird population  have an impact throughout the ecosystem. Photo by Forest and Kim Starr.

This albatross colony on Midway Atoll is representative of what the historic density of seabirds may have been throughout Hawaiʻi. Declines in the seabird population have an impact throughout the ecosystem. Photo by Forest and Kim Starr.

When horticulturalists at Maui Nui Botanical Gardens want to give an extra boost to their most sensitive and critically endangered Hawaiian plants, they bring out the seabird and bat guano. Why guano? It’s the natural nutrient-packed fertilizer that Hawaiian plants are used to.

Prior to the first canoe reaching Hawaiian shores, taloned and feathered beasts ruled these Islands. Scientists estimate that seabird populations on the main Hawaiian Islands were equivalent to what the 18th century explorers found on the Northwest Hawaiian Islands–in other words, plentiful. Some accounts indicate seabirds were so abundant they blackened the sky. And if they could darken the sky with their wings, they were certainly capable of whitening the ground with their poop, aka guano.

Bird droppings may not be welcome on your car, but plants benefit from the splattered remains of a seabird’s meal. Guano is a gift for growing seedlings: high in nitrogen, phosphate, and potassium–nutrients essential for plant development. The more guano drops from the sky, the more plants sprout from the ground. This growth affects the entire ecosystem. As plants decompose, they provide plentiful and nutritious food for insects, nematodes, snails, and assorted detritivores, as well as soil bacteria and fungus.

An ʻuʻau chick in a burrow. Once plentiful, the ground nesting Hawaiian petrel is critically endgangered, threatened by feral cats, mongoose, and barn owls. Photo by Jay Penniman

An ʻuaʻu chick in a burrow. Once plentiful, the ground nesting Hawaiian petrel is critically endangered, threatened by feral cats, mongoose, and barn owls. Photo by Jay Penniman

Hawaii’s seabird populations are only a fraction of what they once were. The ‘ua‘u, or Hawaiian petrel, was once the most abundant seabird in the Islands. Today this burrowing resident is endangered. In Maui County, remnant populations exist atop the summits of Haleakalā on Maui and Lānaʻihale on Lānaʻi. The reason for the species’ decline is simple, yet irreversible. They were gobbled up by people, rats, mongoose, and barn owls; the hillsides where the birds nested are now pastures, golf courses, farms, and shopping centers. Other seabirds, such as the wedge-tailed shearwater, Newell’s shearwater, and Bulwer’s petrel once filled the air with their cries; these species now live in scattered, isolated populations.

If efforts to restore seabird colonies on the main Hawaiian Islands are successful, this may be a site any resident or visitor to Hawaii can see. For now, you have to visit Midway to see Laysan albatross this dense. Photo by Forest and Kim Starr.

If efforts to restore seabird colonies on the main Hawaiian Islands are successful, this may be a site any resident or visitor to Hawaii can see. For now, you have to visit Midway to see Laysan albatross this dense. Photo by Forest and Kim Starr.

Fewer seabirds mean fewer plant fertilizers. We may never fully understand how declines in pelagic bird populations impact the environment in Hawaiʻi, but research on islands in New Zealand offers some insight into what happens when avian populations crash due to introduced predators. Comparing islands that had been invaded by rats with those still dominated by seabirds, researchers found that the soil on rat-infested islands had a much different nutrient composition and pH. Additionally, the types and abundance of insects and other invertebrates varied, possibly due to differing rates of plant growth and nutrient uptake. The scientists concluded that reducing the seabird population triggers effects that cascade through entire ecosystems, down to the smallest microorganism.

Back in Hawaiʻi, there’s an opportunity to find out what happens in reverse–how a seabird-based ecosystem can recover when the invaders are removed. At Kaʻena point on Oʻahu, rats have been eradicated A predator-proof fence now prevents rodents from re-entering the 59-acre protected area. The resurgence of seabirds, with their increasing deposits of poop, will soon boost nitrogen and stimulate the recovery of native plants.

The loss of a single species has implications for the entire ecosystem. In this case, it’s just about the birds, it’s about what they leave behind, what lives off that, and on and on, all the way down.

You can support the restoration of Hawaiian seabird populations. Visit websites for Maui Nui Seabird Recovery Project (www.mauinuiseabirds.org/restoration/) and Hawaiʻi Offshore Islet Restoration Committee to learn more (http://www.hawaiioirc.org/about-us/).

Lissa Strohecker is the public relations and education specialist for the Maui Invasive Species Committee. She holds a biological sciences degree from Montana State University. Kia’i Moku, “Guarding the Island,” is prepared by the Maui Invasive Species Committee to provide information on protecting the island from invasive plants and animals that can threaten the island’s environment, economy and quality of life.

Originally published in the Maui News, February 8th, 2015 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Filed Under: In the field, Invasive Animals, Kia'i Moku Column Tagged With: 2015, fences for rats, Hawaiian seabirds, rats in Hawaii, seabird guano

Predator proof fences: Creating “islands” of protection in the Hawaiian Islands

Posted on July 1, 2013 by Lissa Strohecker Leave a Comment

Sometimes, fences bring freedom.

In Hawai‘i, habitat loss and invasive species have left little room for native plants and animals. And feral cats and dogs attack seabirds. Rats and mice steal eggs from endangered birds and snack on the seeds of rare plants. Introduced snails and chameleons have munched rare native tree snails close to oblivion.

Albatross chicks, like this one on Midway, are becoming an increasingly common sight on O‘ahu at Ka‘ena Point now that a predator-proof fence protects them.

Albatross chicks, like this one on Midway, are becoming an increasingly common sight on O‘ahu at Ka‘ena Point now that a predator-proof fence protects them.

At Ka‘ena Point on the northwest tip of O‘ahu, the Department of Land and Natural Resources tried to protect nesting habitat for seabirds. They closed off the area to motor vehicles and began trapping rats and other predators. It helped—Laysan albatross (mōlī) and Wedge-tailed shearwaters (‘ua‘u kani) began nesting among the native plants and in the dunes of this coastal ecosystem.. In 2011 over 3,000 shearwaters chicks hatched; and by 2012, 61 pairs of albatross took turns sitting atop their single egg. Unfortunately, control efforts only reduced the number of predators; it didn’t stop them. In a typical year, 15% of seabird hatchlings were killed. Periodically, stray dogs wandered into the reserve with catastrophic results. In 2006, 113 shearwaters were killed in a single night. The Department of Land and Natural Resources decided to build a fence.

Predator-proof fencing has been used extensively in New Zealand, but has only recently gained favor in Hawai‘i. It offers a promising solution for ongoing struggles like those at Ka‘ena. Rather than ongoing trapping to remove predators, resource managers can create protected “islands” where native plants and animals have a chance to recover.

The Hawaiian Petrel or ‘ua‘u is one of several species that cold benefit from a predator proof fence on West Maui. photo by jay Penniman

The Hawaiian Petrel or ‘ua‘u is one of several species that cold benefit from a predator proof fence on West Maui. Photo by Jay Penniman

On Maui, two fenced enclosures are currently being built on the windward side of the West Maui Mountains at Makamaka‘ole. One is for Newell’s shearwaters, or ‘a‘o, and the other is for Hawaiian petrels, or ‘ua‘u.  Both species nest in underground burrows and are vulnerable to attack by rodents, mongoose, and feral cats. The fences are designed to keep these hungry creatures out.  First Wind, which built Kaheawa wind farm, is creating the four-acre enclosures as part of their seabird mitigation program to address impacts caused by the towers.

The Makamaka‘ole fences will be similar to the one at Ka‘ena. The mesh on these predator-proof fences is so small that even two-day old mice can’t crawl through. The fence will be topped with a metal hood to keep any animals from climbing over, and a skirt extends along the base to keep animals from burrowing under.

Once the first enclosure at Makamaka‘ole is complete, invasive animals will be removed and sound systems will be installed that broadcast seabird calls to attract prospecting birds. If they land to investigate, they may find home in one of the 50 artificial burrows. Erica Thoele, supervisor of habitat conservation plan compliance with First Wind, says, “Hopefully they’ll think this is a safe place and build a nest,” says Thoele.  Crews will trap for predators along a 100 yard perimeter outside the fence in case any seabirds decide to nest nearby.  Ongoing monitoring will help evaluate whether seabirds are using the artificial burrows or digging their own nests in the enclosure.

Monitoring at Ka‘ena Point has shown promising results. The 700 yard fence was completed in March 2011 and protects 59 acres of coastline from predators. There have been dramatic increases in seabird productivity now that the rats have been removed- a 25% increase in the number of albatross nesting at Ka‘ena, and a doubling of the number of Wedge-tailed shearwater chicks fledging. Native plants are also showing signs of recovering with more abundant fruits, seeds and seedlings than had been observed prior to removing predators. The fences may keep the hungry critters out, but well-behaved humans are still welcome at Ka‘ena. Double-door gates along the fence allow access to the reserve.

Fencing projects elsewhere in the state are in the works. The Oahu Army Natural Resources Program built “snail” fences to protect rare native snails from rats, mice, Jackson’s chameleons, and the invasive rosy wolf snail. A new fence will be built next year at Kīlauea Point National Wildlife Refuge to enclose nearly eight acres of habitat for six different species of breeding seabirds. Plans are in process for a fence on Lāna‘ihale to protect ‘ua‘u nesting habitat. Learn more about predator proof fencing at Ka‘ena by visiting the website hawaii.gov/dlnr/chair/pio/nr/2011/NR10-225.pdf

By Lissa Fox Strohecker. Originally published in the Maui News, June 9th, 2013 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Filed Under: In the field, Kia'i Moku Column, Solutions Tagged With: 2013, fences for rats, Kaena point fence, Lanaihale fence, predator proof fences Hawaii, West Maui fence

Like us on Facebook

Get Involved

  • Donate
  • Classroom Visits and Presentations
  • Meetings Minutes
  • Report a Pest
PCSU logo

Contact Us

Maui Invasive Species Committee (MISC)
Office: (808) 573-6472
Press and Media Inquiries: (808) 344-2756
Mailing Address:
PO Box 983, Makawao, HI 96768

Acting Manager / Public Relations: Lissa Strohecker
E-mail: miscpr@hawaii.edu

Special Projects: Teya Penniman
E-mail: miscmgr@hawaii.edu

Statewide Pest Hotline: 808-643-PEST
Report a Pest Online

© 2025 Maui Invasive Species Committee (MISC) • Sitemap • Log in