The nene, which somewhat resembles the Canada goose, was once nearly extinct due to hunters and feral predators. Protection and propagation programs have increased its numbers, but it is still considered endangered. They are commonly found at the top of 'ohi'a lehua trees feeding on the nectar of the blossoms. You may spot them on Crater Rim Trail, as you can look down on the treetops from the trail. Mauna Loa Strip Road is also a good place to look and listen for native birds.
Mynahs have regular roosting trees, and their clamor can be heard for great distances.
The Polynesians, and later Westerners, introduced a variety of animals, including the cow, goat, pig, rat, cat, and mongoose. All of these in a feral, or wild, state cause considerable destruction and are responsible for the extinction of many species in the plant and animal community. Pigs are especially harmful in the hapu'u forests, uprooting and killing the tree ferns. Pigs and mongooses destroy bird habitats and nests. Within the park, pigs are actively controlled by hunting and fencing.