Nesting ‘Alalā Indicates Recovery Milestone

Researchers discover a new sign of hope as wild ‘Alalā begin to nest, but concerns over future habitat in the face of Rapid ʻŌhi‘a Death looms.

For almost twenty years, the ʻAlalā or Hawaiian Crow has been considered extinct-in-the-wild after their population declined due to the threat of invasive species. However, conservationists refused to let them die out and have created a captive-breeding program to carry the species until they could one day return to the wild.

Today, a few ʻAlalā are once again flying free in the forests of Hawaii and while new nests give a sign of hope of the species, complex ecological interactions are a new concern for conservationists.

Before the Hawaiian Crow disappeared from its native habitat, the species was found only in the western and southeastern parts of Hawai’i and was considered an indicator species—a species whose decline signifies a larger impact or threat to other wildlife. The birds would nest in the ʻŌhi‘a Lehua and Koa Trees, which protected them from predators, specifically the Io’ or Hawaiian Hawk.

The Hawaiian Crow suffered decades of decline due to invasive predators and diseases, which has caused a major impact on the archipelago’s ecosystem. Its disappearance from the wild has influenced cascading effects on the environment. Native Hawaiian plants rely on the ʻAlalā for seed dispersal and germination; without the ʻAlalā, the plants are unable to produce further generations.   

[Seed dispersal by a captive corvid: the role of the ‘Alalā] study provides evidence that ‘Alalā have the capacity to play a vital role in maintaining the diversity of fruiting plants in native Hawaiian forests through seed dispersal and enhanced seed germination, thus adding greater urgency to efforts to restore ‘Alalā to their former range.”

Ecological Society of America

This is considered an ecological cascade—a series of secondary ecosystem impacts triggered by the primary extinction or decline of a key species in an ecosystem. The disappearance of the ʻAlalā explains, in part, the broader ecological decline throughout Hawaii. Specifically, the near extinction of the spread of Rapid ʻŌhi‘a Death that is decimating the native trees.

Without the ʻAlalā there to manage growth and seed dispersal, the ʻŌhi‘a Trees have been forced into a limited range of space with less variation between them. These restrictions made the trees more susceptible to dangerous diseases, like the Rapid ʻŌhi‘a Death Strain.

Restoring the ecological processes that support Hawai‘i’s native ecosystems will rely on the reciprocal restoration of native birds and plants, in concert with efforts to reduce other serious threats such as invasive species.

Ecological Society of America

After reintroducing a few rehabilitated pairs of ‘Alalā, the researchers discovered that:

Most of the mated pairs chose to make their nest attempts in the ‘Ōhi’a tree, a native flowering evergreen preferred by breeding ‘Alalā. Unfortunately for the project, the species’ reliance on these trees adds a layer of complexity to the reintroduction effort. The ‘Ōhi’a is threatened by an invasive fungal species that swiftly kills the trees, which make up a large portion of Hawaii’s forests. “

Kristine Liao, Audubon Magazine

It is clear to see that when the ecosystem is thrown off balance, everyone that relies on it is affected. However, with the intensified conservation efforts of the ‘Alalā Recovery Project, there is hope. Today, a few ‘Alalā are once again flying free in the forests of Hawai’i and researchers recently observed a pair of their captive-bred crows successfully construct a nest. With any luck, the reintroduction of ‘Alalā will have its own cascading benefits, resulting in the recovery of Hawai’i’s native forests.

Featured photo: ‘Alalā perched on a branch. Credit: US Fish and Wildlife Service

Sources:
Audubon Magazine
Culliney, S. , Pejchar, L. , Switzer, R. and Ruiz-Gutierrez, V. (2012), Seed dispersal by a captive corvid: the role of the ‘Alalā (Corvus hawaiiensis) in shaping Hawai‘i’s plant communities. Ecological Applications, 22: 1718-1732. doi:10.1890/11-1613.1