Kona Hema Preserve

The Need for Trees

Driving through TNC’s Kona Hema Preserve on Hawai‘i Island is a journey through time. This 8,245-acre preserve showcases a stunning transition from sprawling black lava fields of pāhoehoe and ʻaʻā to areas of new seedlings reaching for the sky, culminating in dense koa-‘ōhi‘a forests. It stands as a testament to restoration, hope and resilience.

Like many regions in Hawai‘i, this landscape has been heavily impacted by ranching and logging. Invasive plants and non-native feral animals have exacerbated these losses:  aggressive weeds outpace native plants, while herds of feral goats, sheep and pigs consume native vegetation. Over the years, wildfires have ravaged hundreds of acres, destroying ancient forests and further facilitating the spread of invasive species.

Despite these challenges, thousands of acres of native forest still remain at higher elevations, home to rich stands of koa and ‘ōhi‘a trees. Endangered species unique to Hawaiʻi, such as the ‘Alawī (Hawai‘i Creeper), ʻōpeʻapeʻa (Hawaiian hoary bat) and the ʻiʻiwi (a scarlet forest bird with a curved beak) thrive in Kona Hema. Others, including  the ʻio (Hawaiian hawk), and more common forest birds such as the ʻapapane, ʻelepaio, and ʻamakihi—also flourish in this healthy habitat.

To enhance the forests of Kona Hema, TNC has installed 25 miles of fencing and focused on removing invasive weeds and non-native animals. In many areas, native plants and trees have rebounded once these threats were eliminated. TNC has also unearthed dormant seeds in former pastures, leading to the regeneration of koa forests.

Shalan Crysdale, TNC’s Hawaiʻi Island Program Director, notes, “While we have had wonderful successes and native ʻōhiʻa and koa were able to naturally regenerate, the diversity in these areas was low. The forests were ‘monotypic’ and lacked many native species.”  To remedy this, TNC and our partners have planted nearly 16,000 native trees and shrubs across the preserve, creating more diverse habitats and food sources for native forest birds. 

Adapting to a Changing Climate

While our efforts have fostered a vibrant forest and provided a safe haven for rare and endangered birds, new threats loom in this sanctuary. Temperatures are rising due to climate change and forests are becoming hotter and drier, making quality bird habitats increasingly vulnerable. Wildfires, which are not a natural part of Hawaiʻi’s ecosystems, pose a significant threat—if a native forest burns, it can take generations to restore, time that endangered forest birds cannot afford. Non-native mosquitoes are also taking advantage of warmer temperatures by moving up the mountains into safe habitats, including at Kona Hema Preserve. These mosquitoes carry diseases such as avian malaria, which can be fatal to native forest birds with just one bite.

So how can we encourage native forest birds like the ‘i‘iwi to remain at higher elevations, where they are safer from mosquitoes? One solution lies in planting a diverse array of nectar-producing native trees in new locations. ʻIʻiwi and other native birds depend on the ʻōhiʻa lehua bloom for food; after the bloom ends, they typically descend in search of sustenance. To counter this, TNC is establishing new māmane tree groves by planting 3,000 seedlings at upper elevations within our preserve. Because māmane tend to bloom longer and later than ʻōhiʻa lehua, these new groves aim to entice ʻiʻiwi and other native birds to stay at higher elevations, keeping them safe from the mosquitoes that carry avian malaria.

Feeding the Need for Trees

To continue restoring and diversifying the forest, we need a steady supply of native seeds and seedlings. Jodie Rosam, TNC’s Kona Hema Preserve Field Coordinator, explains, “We call it the need for seed. Across agencies, the biggest inhibitor to large-scale restoration projects is often seed availability.”

Skilled propagation of Hawaiʻi’s native plants is both an art and a science, requiring intimate knowledge and around-the-clock care. More large-scale and high-quality plant nurseries, supported by expert knowledge, are vital for successful forest conservation efforts, yet capacity remains limited on Hawaiʻi Island and throughout the state.

While TNC’s initiatives are yielding positive results in preserves like Kona Hema, everyone can contribute to the preservation of Hawaiʻi’s native forests and birds. Here are some ways to take action:

• Learn about native plants and birds and share that knowledge.
• Grow native plants and remove invasive weeds around your home.
• Eliminate standing water to reduce mosquito habitats.
• Volunteer at conservation events.
• Support policies that prioritize the care of native plants and animals.
• Keep cats indoors.

Kona Hema Preserve is a beacon of hope for both birds and people. As Crysdale puts it, “There’s a mental health component to all this restoration work. Communities are often stricken by hopelessness and there’s a lot that goes on in our heads. It’s important to know that there are places becoming better, not worse, like Kona Hema.”