Only about 200 to 250 of the endangered birds live in the park, and their numbers have failed to increase over the years because of a high mortality rate among goslings, said park spokeswoman Jennifer Talken-Spaulding. Statewide, there are about 900 nene, the official state bird.

A research project is under way to study what can be done to help the young birds survive. Park biologists suspect that the region's arid conditions fail to provide an adequate food source, said Talken-Spaulding. The nene eat grasses, seeds, buds, flowers, leaves, fruits and berries.

Nene are better-suited for lower elevations outside the park boundaries where rainfall is more plentiful, she said. Although the high country in the crater is not the best habitat, it does provide the geese protection from predators such as feral cats and mongooses.

The Paliku wilderness area is one of the wettest spots in the park, and that's where nine nests were counted this week in and around campsites, Talken-Spaulding said. To protect the nest sites and the goslings after they hatch, park officials are limiting camping at Paliku to a maximum of three groups, not to exceed a total of 10 people. The restriction will be in place through March 31.

Adult nene with goslings in Haleakala National Park on Maui. NPS

The restrictions also will help limit human traffic near the nests, she said. Hikers should not disturb the natural feeding or nesting patterns of nene and should maintain their distance from the birds.

The nesting season from October through March is also when the birds frequently cross the park road and are at risk of being run over.

The nene do not flee when approached by vehicles because visitors often feed the birds from their cars.

Talken-Spaulding said park biologists are still feeling the loss of one of the park's most prolific breeders, which was killed a year ago when it was hit by a car. The bird produced 20 offspring that are now among the wild nene at Haleakala.