Conservation

Reintroduced Hawaiian Crows Are Learning How to Live in the Wild

Extinct in their natural habitat for two decades, a small population of ‘Alalā are starting to forage, mate, and nest on their own.

This spring, a pair of Hawaiian Crows did something remarkable: They built a nest. 

First, though, the birds tried out a few potential locations, placing sticks in the crooks of several different trees. Eventually they chose a native ‘Ōhi’a tree to construct their home high up in the canopy, some 40 feet above the ground. Soon after, the female took up residence—possibly sitting on eggs—while the male provided her with food. 

For researchers with the ‘Alalā Recovery Project, the entire process was nothing short of thrilling. That’s because this nest was special—the first in two decades that Hawaiian Crows, or ‘Alalā, have completed in the wild. Extinct in their natural habitat since 2002, the birds are part of an ongoing reintroduction attempt in the Pu’u Maka’ala Natural Area Reserve conducted by the project, a collaboration between the State of Hawaii Department of Land and Natural Resources, U.S. Fish and Wildlife Service, and San Diego Zoo Global.

“This was a huge step forward,” says Alison Greggor, a postdoctoral research associate at San Diego Zoo’s Institute for Conservation Research. “As is typical for the first season, we still have an awful lot to learn, but this new development means that we’re doing the right things.”

Unable to easily check on the nest, researchers had to monitor the birds from afar.  Based on the pair's behavior, the team suspects the female laid and incubated eggs for some period of time, though no chicks ended up hatching.

Greggor says she is neither surprised nor disheartened by the lack of reproduction this season; first-time parents are not usually successful, and these reintroduced birds have no experienced adults to learn from. Instead, they have to figure out the strategies of courtship and nest-building on their own.

Three years ago such a big milestone might have seemed unlikely. In 2016, an unsuccessful reintroduction saw three of the five birds die—two from hawk attacks and one from environmental stressors. But the following year, the project released 11 more birds, and the year after that another 10 flew into the wild. This year, three more crows have entered the free-living population, and another cohort will join them at the end of this month. 

Since the 2016 deaths, the scientists have made many changes based on what they learned, including enhancing the way they choose release sites, moving supplemental feeding stations to reduce territorial tensions, and being more selective when choosing which birds to reintroduce. 

A breeding pair during the 2019 season. Photo: San Diego Zoo Global

“We take a really good look at the social interactions between the birds before we release them so that we can maximize the chance that they stick together,” Greggor says. “With more eyes on the sky for predators and more eyes on the ground for feeding opportunities, there’s a strength in numbers.”

Although a few more crows have died, suffered injuries, or gone missing in the past three years, the remaining Alalā, which now number in the twenties, have been adapting quite well to their new home in the forest and are increasingly exhibiting natural behaviors. The birds have been foraging on native fruiting plants, challenging predators like the ‘Io, or Hawaiian Hawk, and opportunistically feeding on eggs and nestlings of other forest bird species. These are positive signs, especially as the team begins trying to wean the birds off their supplemental feeders and to become more independent. 

In addition to a more natural diet, the birds have also started engaging in courtship behaviors and formed multiple breeding pairs, many of which went on to display preliminary nest-building efforts (though only one pair successfully completed a nest). 

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. 

Such complications are what make any reintroduction difficult, and though the crows have shown encouraging progress, the researchers are aware of how fragile the situation remains. Next up in the plans is to release birds in areas other than the Pu’u Maka’ala Natural Area Reserve and to continue spreading awareness to local communities about the importance of restoring Alalā to their natural habitat. 

“It’s really important to keep in mind that it takes many years to establish a species back to the wild,” says project coordinator Jackie Gaudioso-Levita. “We’re all in it for the long haul.

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