Kiwikiu Recovery
MAUI'S MOST CRITICALLY ENDANGERED FOREST BIRDThe kiwikiu (Maui Parrotbill; Pseudonestor xanthophrys) is a critically endangered Hawaiian honeycreeper only found on the island of Maui. Once found across Maui and Moloka‘i, the kiwikiu now survives in just 20 km² of wet rainforest on the windward side of East Maui. Historically and from fossil evidence, its range included various forest types, from high-elevation wet forests to lowland dry forests.
Like many native Hawaiian forest birds, the kiwikiu faces threats from non-native species, habitat loss, and climate change. Widespread deforestation for agriculture and grazing has drastically reduced the island’s native forests. Invasive plants and animals have further degraded these habitats. Additionally, introduced predators impact their breeding success and introduced avian diseases and mosquitoes now restrict the kiwikiu to forests above 5,500 feet (1,600 meters), where disease and mosquitoes are less common.
Today, the kiwikiu’s remaining habitat is confined to protected areas on the windward slopes of Haleakalā, from The Nature Conservancy’s Waikamoi Preserve in the west to the State of Hawai’i’s Hanawi Natural Area Reserve (NAR) thought Haleakalā National Park to the Manawainui Planeze.
Species Status: Endangered
The first comprehensive population survey of the kiwikiu was conducted in 1980 as part of the Hawai‘i Forest Bird Surveys, with an estimated population of about 500 individuals. By 2017, the population had declined to 44- 312 individuals. In 2022, our estimate dropped further to 20- 168 individuals. Mean population estimates between 2017 and 2022, indicate a ~44% decline. While population estimates for the kiwikiu have variability and low precision, these numbers confirm that the species is rare and continues to decline.
Current rates of reproduction and survival are insufficient to sustain the kiwikiu population in the long term. Population viability analysis predicts the species could go extinct within 5 years. While the kiwikiu’s remaining habitat is well-protected, with ongoing efforts to remove ungulates and invasive species and to plant native trees, there are still significant challenges. Managers lack the tools needed to address the full range of threats at the landscape scale including including avian disease, predator control, and climate change impacts. Climate models predict that by ~2100, suitable habitat on the windward slopes of Maui could shrink to just 7 km², further threatening the species’ survival.
Protecting the Kiwikiu: Our Research and Management Strategies
See Research and Publications.
Beginning in 2006, MFBRP began focusing on finding more about the kiwikiu’s biology and demographics. We used spot-mapping techniques, mist-netting and color-banding individuals for resights, and searched for pairs, nests, and young. This allowed us to estimate relative density, home-range, productivity, and survival. We found that kiwikiu live for over 15 years forming (mostly) socially monogamous pairs that typically produce only a single offspring every year or two. Immature birds remain with their parents for up to18 months. They have high adult survivorship but low juvenile survivorship. Home range size for an individual is quite large: ~9 ha on average. Nest success is low and they typically fail from severe weather and predation events.
We also analyzed blood samples to understand genetic structure across range and time. These genetic studies help us select individuals from appropriate locations to maximize genetic diversity for translocations and/or captive management.
We continue to conduct surveys to estimate and monitor the population.
Conservation Translocation Leads to Increased Focus on Disease Management
Prior to 2020, the U.S. Fish and Wildlife Service (USFWS) Recovery Plan (2006) called for the creation of a second population of kiwikiu within its historical range to protect the species from catastrophic loss in its small current range. The south slope (leeward side) of East Maui was deemed the best site for a reintroduction since kiwikiu were once found there, there was remnant native forest that was being restored, and there were less extreme weather events. In 2012, a 170-ha section within Nakula Natural Area Reserve in the Kahikinui region of leeward Haleakalā was fenced and became ungulate free. Along with partners, we began working to restore this forest. To make sure prey was available for the kiwikiu, arthropod surveys were completed. We assessed mosquito, disease, and predator levels and then implemented predator and mosquito control efforts to protect the translocated birds.
In 2019, after many years of planning, we translocated 14 kiwikiu to Nakula: 7 from a conservation breeding facility managed by San Diego Zoo Wildlife Alliance and 7 that we captured from the wild in Hanawi NAR. They were placed into aviaries within the translocation site prior to release and then monitored using radio telemetry. Read the 2019 Kiwikiu Conservation Translocation Report here.
Unfortunately, most of the kiwikiu died from avian malaria spread by unprecedented levels (28x higher than previous years) of mosquitoes in the reserve due to a warm, dry year. Those that survived, one captive kiwikiu returned to captive-care and received treatment for malaria and one wild kiwikiu returned on his own to his original capture location.
Although the release did not ensure a second population of kiwikiu, we learned that kiwikiu could survive in Nakula if not for disease. Climate change was changing the dynamics of disease in what had been considered native habitat refugia.
Updated Recommended Conservation Management
The rapid increase in mosquito numbers at the release site raised concerns about the spread of disease elsewhere on Maui. New strategies were needed as well as more research. We continued assessing the kiwikiu population as well as disease and mosquito prevalence in different locations across the habitat of East Maui.
Paxton et al. (2022) surveyed expert opinions, both biological and cultural, to re-evaluate recovery options for kiwikiu and three other endangered honeycreepers. These evaluations were presented to the State and Federal decision makers for guidance on the next steps for Hawaiian honeycreeper recovery. The strategy is summarized below:
- Develop and deploy Incompatible Insect Technique (IIT) to reduce the mosquito vector of avian malaria.
- Establish captive care programs for bird species most at-risk of near-term extinction.
- Identify species that are appropriate for translocation and implement translocation to high elevation refugia on Hawai‘i Island.
- Develop and deploy next-generation tools.
- Develop and implement conservation strategies informed with Native Hawaiian bicultural knowledge and deployed with appropriate protocols and cultural practices.
Removing mosquitoes and thus the vector for disease in native forests is the most important management strategy to prevent extinction of kiwikiu in the wild. We are currently exploring mosquito reduction options but they may not be implemented at the landscape scale in time to prevent kiwikiu extinction. Thus bringing some individuals into human care to create a population that can be released once mosquito populations have decreased, is being set up to ensure kiwikiu continue to exist.
The San Diego Zoo Wildlife Alliance manages the Hawaiian Endangered Bird Conservation Breeding Program at the Maui Bird Conservation Center and Keauhou Bird Conservation Center on Maui and Hawaiʻi Islands. They care for several Hawaiian bird species.
A kiwikiu captive population was initiated in 1997, but remained small for the next 20 years due to a small number of founding individuals and the kiwikiu’s unique life history characteristics (pair bonding, one egg per clutch, long juvenile dependency). Nearly all individuals were released in the 2019 translocation. Thus, we needed to start a new and invigorated conservation breeding program. In 2024, we began bringing a small number of wild kiwikiu into human care at the Maui Bird Conservation Center to create a viable captive population that can eventually be released into the wild once mosquito populations have been reduced.
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