4. The Egg and Hatching
By the end of November or early December, a pair of mates lay a egg that is about 3.5 inches long and 2.5 inches wide. The incubation period for the egg is 60-65 days. Not much happens at the nest. The parents rotate feeding and sitting, generally changing places about once a week. in spite of the long, boring wait at the nest, the mate being relieve is often reluctant to leave the egg. We have observed the returning mate gently nudging the mate off of the egg, to take over the duties.
Good eggs: As part of ongoing research, FWS has sent teams to determine the viability of egg being incubated. Working at night, the biologist hold a flashlight on one side of the egg to illuminate the interior. Signs of a good egg are visible blood vessels and the presence of an air sac, shown here as the brighter arc at the right end of this egg.
Roughly 40-50% of the eggs turn out to be infertile. The mates will sit on a bad egg for weeks past the normal incubation period, just to be sure it's not going to hatch. They are extremely dedicated.
This brings up the subject of female-female pairings, which accounts for many of the infertile eggs. Two females sometimes form a strong bond, acting the same as the male-female mates in sharing the responsibility for the egg. Occasionally, the egg is fertile, resulting from a chance encounter with a male prior to the laying. When a chick does hatch, the female-female pair continue the nurturing process until it fledges. They are excellent parents when given the chance.
Coming Out: After 60-65 days for a viable egg, the chick starts the process of emerging. The first sign of a hatching is the "pip", a small hole in the end of the egg poked out from inside by the live chick. Once the pip is seen, it takes 48-72 hours for the chick to fully emerge from the shell, as it slowly enlarges the hole and breaks up the shell. The parent watches, but does not help, except to gently massage the chick with its beak to stimulate it. Biologists point out this arduous task ensures the chick is strong enough to survive.
Hatching happens in the last week of January and the first two weeks of February. By mid-February, all of the chicks that will survive in that year are free of the shell.
This photo shows a chick just a few hours old. Chicks are often given nicknames by the property owners. This new arrival in 2007 is named Leilani. Tagged that year as K247, she has returned to Kauai as an adult and is just now reaching breeding age.