The Nēnē, or Hawaiian Goose (Branta sandvicensis), is the world’s most terrestrial goose and the state bird of Hawaiʻi. This endemic species remains federally listed as threatened under the Endangered Species Act. The Nēnē is an herbivore, adapted to graze and browse on the diverse plant life of the Hawaiian Islands, a diet that has allowed it to survive across a wide range of habitats. Understanding their wild food sources is paramount for conservation efforts focused on their continued recovery.
Primary Diet of a Native Hawaiian Grazer
The Nēnē’s diet is primarily vegetarian, consisting of leaves, seeds, flowers, and fruits from at least 50 native and non-native plant species. As specialized grazers and browsers, they consume a variety of herbaceous plants, sedges, and grasses. Their food selection is driven by nutritional content, with a preference for young, tender vegetation that offers higher protein and water content. They actively seek out native flora like the leaves and fruits of shrubs such as pūkiawe and ʻaʻaliʻi, and the berries of plants like ʻōhelo. While they are naturally adapted to native plants, they now also feed on non-native grasses due to the loss of historical lowland habitat; conservationists work to restore nutritious native plants important for gosling growth.
Foraging Behavior and Methods of Consumption
The Nēnē is a highly terrestrial bird, a trait reflected in its foraging techniques. They use their beaks to pull and strip plant material, often focusing on the most nutrient-rich parts, such as the basal, lower portions of grass blades. This method of consumption allows them to access the tender shoots and leaves close to the ground, avoiding the tougher, less digestible mature parts of the plant. The geese also play an important ecological role as seed dispersers, consuming fruits and seeds that pass through their digestive system intact. While their primary energy source remains grazing on leaves and shoots, their feeding habits also involve stripping seeds directly from stems or pulling up geophytes; this continuous grazing influences the composition of early successional plant communities.
Geographic Variations in the Nēnē Diet
The diet of the Nēnē is not uniform across the islands, reflecting the diverse and geographically isolated habitats of Hawaiʻi. Populations range from sea level to nearly 8,000 feet, and the available food sources change dramatically with elevation and moisture. For example, Nēnē living in the dry, high-altitude shrublands of Haleakalā or the Big Island’s volcanic slopes often rely on the small, persistent leaves and berries of the pūkiawe shrub. Conversely, Nēnē inhabiting low-elevation, non-native grasslands, such as those near the coast on Kauaʻi, will consume a greater proportion of introduced grasses and sedges. Their ability to utilize non-native species aids survival, though the nutritional quality of these foods can be inconsistent; this variation highlights the importance of managing a diverse suite of food plants across the different islands.
Harmful Foods and Recommendations for Public Interaction
Human interaction, particularly feeding, poses a significant threat to Nēnē well-being by altering their natural behavior and diet. Foods provided by people, such as bread, processed snacks, and high-sugar items, lack the necessary nutritional content for the geese and can cause health issues. Nēnē consuming cat food has been shown to negatively impact their health and is not a natural dietary item. The consumption of unnatural foods draws the geese to human-managed areas like roadsides and parks, making them vulnerable to vehicle strikes and predation by introduced animals. The public is strongly advised to never feed Nēnē, as this habituates them to humans; keeping pets leashed and avoiding outdoor feeding stations helps ensure the geese rely on natural, healthy forage.