WEDGE-TAILED SHEARWATER (Puffinus pacificus, now Ardenna Pacifica) -‘Ua’u Kani – (See images below)
DESCRIPTION: The Wedge-tailed Shearwater comes in two color morphs, one being mostly dark brown and a ‘pale’ one with only the head being dark (see photos/videos below). The upper body is mostly medium grey and the under parts washed out white with grey bands on the wings. The bird is about 15 inches (40 cm) long.
The bill is grey and the tip is curved downward. This bird is a ‘tubenose‘ species, i.e. with bony tubes attached to their bill, which are part of a system to extract salt from ocean water, and also for olfaction.
The tail is wedge shaped (hence the name). The pink legs are positioned further back to help with swimming, but it makes it more difficult for the bird to move on land. This species has a moaning call (hence the Hawaiian name).
NAME: The name ‘Shearwater’ means that the bird’s long, straight wings barely touch the water when looking for fish at the surface. The genus ‘Puffinus’ for this shearwater was changed in 2014 to ‘Ardenna’, following genetic analysis. The name ‘Ardenna’ was first given to a seabird by Italian naturalist Ulisse Aldrovandi in 1603.
HABITAT: This species is ‘pelagic’, i.e. spends its life over the open oceans.
DIET: Schools of fish or flying squid brought to the surface by larger predatory fish. Wedge-tailed shearwaters will dive head first, or pick fish while on the water, or will follow ships also.
NESTING: The Wedge-tailed shearwater is a pelagic seabird that only comes to land to nest. It builds – or digs rather – its nest underground, which means the chicks start their life in a dark burrow, a stark contrast to the rest of their lives. Parents return to the same nesting site year after year. A single egg is laid. They form long lasting pairs, and both participate in chick care. They attend the nests at night to avoid predators.
DISTRIBUTION: The range of wedge-tailed shearwaters covers the tropical Pacific and Indian Oceans. It is indigenous to Hawaii.
CONSERVATION: As can be seen below, the nests of this species are very vulnerable on Kaena Point, because they’re built on sand dunes. They can be blocked if being stepped on at the entrance, and predators can easily reach the chicks. This is why a large fence was built in there.
Another threat comes from artificial lighting near the coasts, which can confuse and disorient fledglings at night.
In spite of these threats the numbers of the wedge-tailed shearwater appear stable and large enough to classify this species as ‘least concern’ for now.
NOTES: The wedge-tailed shearwater seen below appeared to be injured or sick, and was trying to hide in a hole at the base of a large tree by the ocean side of the highway at Laniakea Beach (the famous ‘Turtle Beach‘). Based on the time of the year, it didn’t seem to be a fledgling.
Shearwaters are part of an order of birds that includes seabirds with a ‘tubenose’ bill. This highly specialized bill is made of plates and the nostrils are inside one of them in the shape of a ‘tube’. These birds drink seawater, and they have glands in their bill to extract the salt from the water. Their nostrils also have a self-defensive feature – when threatened they can spit out a foul-smelling oil from that organ.
Fact sheet from Hawaii Department of Land and Natural Resources: Wedge-Tailed Shearwater – Hawaii DLNR – Oct. 2005
Here are videos of the wedge-tailed shearwater at Laniakea Beach:
Kamehameha Highway (83) is a high traffic one on the North Shore of Oahu, as can be heard on these two short videos: