Since 1992, numbers of Newell’s shearwaters on Kaua’i have been declining. Although this decline is thought to be associated with the impacts of Hurricane Iniki, which hit the island in 1992, numerous other factors could also be implicated. Artificial lighting on the breeding islands, such as street and resort lights, is affecting large numbers of Newell’s shearwaters. Lights disorientate fledglings as they depart the island for life at sea, causing them to crash into powerlines, communication towers or other structures, or fall to the ground exhausted. Once on the ground, the small birds are vulnerable to cars, cats, dogs, starvation and dehydration, resulting in thousands perishing each year (4).
When nesting, Newell’s shearwater is vulnerable to predation from introduced mammals (4). Feral cats have been recorded killing nesting birds in their burrows (4), and rats are believed to prey on eggs and chicks (6). Also of concern is the small Asian mongoose (Herpestes javanicus), another potential predator that has recently been discovered on Kaua`i (6). Newell’s shearwater is likely to be impacted by the loss and degradation of suitable nesting habitat. Already 75 percent of Kaua’i’s natural forest has been lost in the last 150 years (4), and the remaining forest is now being impacted by introduced plants, pigs and goats (4) (6). Out at sea, overfishing of tuna species, which aid the shearwater by driving prey to the surface, may eventually affect this bird (4).
Finally, given that the majority of Newell’s shearwaters breed on a single island, this makes them highly vulnerable to the impacts of catastrophic events, such as hurricanes (4). The declines observed in this species since the hurricane of 1992 illustrate this sobering situation only too well (6).