HANCOCK COUNTY – The relatively cold weather over the past month might mean an off year for some local residents who live on the water.

The couple – bald eagles whose nest is visible to millions thanks to a webcam linked to the BioDiversity Research Institute Web site – have yet to hatch an egg that they produced on March 5.

Incubation usually takes 35 days from the day an egg is laid until it hatches and produces a live chick, researchers have said. Monday was the due date for the chick to be born.

“The birds have been on and off the nest a lot in the past 24 hours,” Wing Goodale, a research biologist at the Gorham-based institute, said Monday. “I would not be surprised if they fail.”

Below freezing temperatures in early March may have slowed the incubation period, Goodale said, and recent storms certainly have not aided in the incubation process.

If another week passes and there are no signs that any eggs in the nest have hatched, he said, then it can be assumed they will not.

The nest is located in coastal Hancock County. Researchers will not disclose the nest’s exact location for fear of human interference with the wild animals.

Last year, the eagles laid and successfully hatched three eggs. Only two of the resulting chicks survived, however, as the young eagles’ survival instinct took over and the two larger ones killed the third.

The Web site proved to be popular last year, and at one point more than 2 million viewers were logging on each day to get a glimpse of the eagles and their chicks. A link to the camera view of the nest is on the institute’s Web site, www.briloon.org.

Goodale said it is not clear how many eggs are in the nest. Because they are too low in the nest to be seen by the camera, the only indicator researchers have that the eggs are there is the behavior of the parents.

Since March 5, one of the two parents has been sitting in the nest virtually nonstop. Usually it is the mother, but sometimes the father has been sitting on and gently turning the egg or eggs while the mother has flown away. Bald eagles typically lay more than one egg each spring.

If an egg hatches, the adult eagles will sit in the nest with their wings slightly out to help shield the tiny chick from the elements and frequently will bring food to it, according to Goodale.

About 10 days ago, the birds were gone from the nest for about three hours, he said.

“It was 10 to 15 degrees above freezing, which is a good sign,” the scientist said. “Why they left, who knows. We the scientists are learning along with the public.”

Goodale said the parents have produced 20 chicks in the past 13 years, which is twice as many as any other known nesting pair in Maine. If this years’ eggs fail to hatch and the parents leave, scientists will collect them and test them for environmental factors such as mercury exposure, he said.

If the eggs fail, there is an outside chance the pair could try again this spring, but such a scenario is not likely, according to Goodale.

Whether or not they succeed, the ability to observe the birds via the Internet has proven to be a valuable educational tool for scientists and the public alike, he said.

“It’s not uncommon for the birds to fail. The cards are stacked against them a bit, in general,” Goodale said. “We should certainly know something by the end of this week.”