Hawaiian Birds and Newell’s Shearwater Breeding

Newell’s Shearwater breed on Kaua‘i mainly between 525 – 3,936 feet elevation on steep, densely vegetated slopes. They also nest on the dry, sparsely vegetated cliffs of the Na Pali coast. It is here they build their borrows.

At the end of April, adult Newell’s shearwaters arrive at their island nesting grounds. During the beginning of June, they lay a single egg into a burrow which has been dug under matted ferns or tussock grass, often at the base of a tree. The egg is incubated by both parents for around 50 – 60 days, and they continue their parental care when the egg hatches. The parents spend the daylight hours foraging in the ocean surrounding the island, travelling up to 1,200 kilometres from the colony, and returning at night to feed the chick. By November, the young will have fledged and the parents provide no further care, leaving the young to begin their own life on the open ocean. When they fly out to sea, they and are no longer dependent on their parents. During the first year of life, Newell’s shearwaters do not visit breeding islands, but as they age, they will visit colonies for progressively longer periods, until they first breed at the age of six.

In 1908, the Newell’s was thought to be extinct but was rediscovered in 1947 and found breeding on Kauaʻi in 1967. Like many island breeding species, Newell’s Shearwater populations have been decimated over the years by hunting, habitat loss, avian malaria, and predators. This latter threat is now the most serious one facing the species. The eggs, young, and adults are vulnerable to attack by introduced cats, rats, mongoose, pigs, and Barn Owls. Effects of urbanization, including collisions with power lines during their nocturnal flights, and the fatal behavior of encircling city lights, are also cause for concern as hundreds of birds are killed annually from these factors.
Photo by Jim Denny