Ecology and Demography of Hawaiian Forest Birds

Science Center Objects

Many of Hawai‘i’s forest birds have shown significant declines in the past 200 years, with many currently listed as endangered species. Multiple threats have been identified as contributing to declines, including disease, invasive species, habitat loss, and decreased survivorship and productivity caused by introduced predators.  Demographic and ecological studies are needed to determine how different factors effect population health and viability, and models need to be developed to determine the relative effects of different factors. 

Iiwi in an ohia tree

An ‘i‘iwi in an ‘ōhi‘a tree. Photo: K. Burnett

Hawaii akepa in hand

Hawai‘i akepa captured at Hakalau Forest National Wildlife Refuge, Hawai‘i Island. Photo: USGS

Overview:

Hawai‘i’s forest birds are one of the most imperiled group of birds in the world.  A large number of threats currently exist, and climate change threatens to bring more pressure on the species.  This research combines empirical research and population modeling to provide insights into threats and help mangers develop conservation strategies to ensure persistence of these species of birds.  A number of interrelated, complementary projects are underway toward this end. Field demographic and ecological studies are being conducted at key forest bird reserves and ecological models are being developed to better understand forest bird population dynamics to provide information valuable for resource managers.

Project Objectives:

Quantify and understand factors limiting populations of native Hawaiian birds, specifically how factors affect survivorship, productivity, and movement, and develop information to aid managers in conservation actions. Better understand links between habitat characteristics (quality) and population densities and viability of Hawaiian forest birds.  Explore the development of disease resistance in native Hawaiian bird populations.

Highlights and Key Findings:

We have brought together multiple lines of research, studies of survival, productivity, movement, and are combining them into models that allow us to understand processes influencing population dynamics, evaluate effectiveness of conservation actions, and make predictions about the impact of future events.

Banding table setup

Banding station set-up at Hakalau Forest National Wildlife Refuge. Photo: E. Paxton

At Hakalau Forest National Wildlife Refuge (NWR), on the island of Hawai‘i, we completed 5 seasons (2012–2016) of demographic research (mark and recapture and nest monitoring) for Hawai‘i forest birds. During this time more than: 3,600 birds were banded, 1,350 banded birds were recaptured, and 900 forest bird nests were found. Additionally, using a network of automated radio telemetry tracking towers around Hakalau Forest NWR we tracked long-distance movements in two species, ‘I‘iwi and Apapane, and we have linked movements with demographic findings. Using historical datasets and recent research results we have developed demographic models to understand and predict population dynamics.

Studies on the island of Kaua‘i have explored the population size and viability forest bird populations restricted to the island.

Progress:

Completed Analyses and results are detailed in peer-reviewed publications listed under the Publications tab. 

Apapane perched on a branch

Apapane perched on a branch. Photo: R. Kohley