Hawai'i Volcanoes National Park scientists are celebrating the most successful breeding year ever for the endangered nene goose, with 36 goslings surviving long enough to take their first flights.

Normally, only about 15 newly hatched geese survive to become fledglings, or birds on their first flights, said Superintendent Cindy Orlando.

Park biologist Kathleen Misajon said favorable weather helped with the breeding program. There was enough rain in the critical months of October, November and December to keep the vegetation green and growing, but not so much that nests flooded and goslings died from the wet and cold.

"The flocks of wild geese seen flying overhead and gathering at the golf course are a testament to the success of this year's breeding season," Misajon said. "When it comes to nene survival, we all make a difference. Our continued care and vigilance will help ensure a future for these rare birds."

Parks officials said safety improvements designed to protect the nesting birds helped boost the survival rate of the goslings.

New "Nene Crossing" signs alerted drivers to the presence of geese on park roadways, including 14 signs donated by James Brogan of Signs Hawai'i in Honolulu. Brogan donated the signs after he heard about two nene-warning signs that were stolen from the park in 2004.

"We credit his signs with playing a critical role in the survival of one family who regularly crossed Crater Rim Drive in search of food for their three goslings," Misajon said. "The goslings fledged and are the first to survive from the Devastation Trail area in 10 years."

At 'Ainahou, a mid-elevation woodland on Kilauea, staff kept watch over a 420-acre fenced enclosure that protected 10 families of geese from predation by wild pigs.

Four other nene families found refuge in a 13-acre enclosure built to keep out feral cats and mongooses, and at least four goslings fledged from the lush green pastures of Kapapala Ranch on the park's western boundary, parks officials said.

During the past five years, an infusion of young birds reared at the Keauhou Bird Conservation Center into the park population has significantly boosted the number of breeding pairs.

Those releases, coupled with the relative success of the past several breeding seasons, have increased the number of young birds in the park, and the young geese are now reaching reproductive maturity and beginning to produce offspring.

Seven new pairs successfully raised goslings for the first time, contributing a total of 12 fledglings to this year's count.

Now that nesting season has ended, flocking season has begun and birds are congregating at prime feeding locations to fatten up for the fall breeding season. Families socialize, young birds meet the rest of the flock, and single birds size up potential mates.

Volcano Golf and Country Club is a favorite flocking area, and groups of 25 or more birds already have been seen lazing and grazing on the fairways.

Nene that congregate near Pi'i Mauna Drive and other roads through the golf course are at risk of being injured and killed by cars, and the park is working with the Volcano Golf and County Club and county officials to install new "Slow for Nene" signs, and to distribute information to golfers.

Parks officials ask that people who encounter nene not feed the geese, and to drive slowly. The birds tend to gather near the road, and their grayish coloration makes them difficult to see.

Dogs are not allowed on the golf course, and should be kept on a leash because some dogs have attacked nene.

Parks officials ask that golfers "gently shoo the birds out of harm's way before playing through."

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.