Tuesday, January 20, 2009 - Mystery Pterodroma petrel in Easter Island, Chile

Mystery Pterodroma petrel | Providence Petrel (Pterodroma solandri) or Henderson Petrel (Pterodroma atrata)?.

Photographs by Enrique Couve taken at Puna Pau, Rapa Nui (Easter Island) on 1st August 2006.

These pictures were taken from a considerable distance at one of the extinct volcanoes of Puna Pau, near the village of Hanga Roa, Easter Island or Rapa Nui. This locality is locally known as the "Quarry of the hats".

A few individuals of this completely dark grey-brown, heavily-built, broad winged, wedge-tailed gadfly petrel were seen at sunset time, soaring over the fields.

The similar Kermadec Petrel and Herald petrels are common nesters of the motus (islets) located in the eastern coast of the main island. The completely dark Henderson Petrel (Pterodroma atrata) has been previously reported by Jaramillo et al. to the island.

Kermadec Petrel has distinctive primary white shafts in the upperwing at all the phases, even in very dark individuals. This feature is normally quite distinctive in the field. It is a stocky petrel with broad wings and broad wedge-shaped tail.

The slim, lightly-built Henderson Petrel resembles the jizz of Herald Petrel (Pterodroma heraldica), with long pointed wings and the tail normally held very tightly closed. According to Jaramillo and several other authors, Henderson Petrel has whitish patagium, a fade silvery look at the base of primaries and lighter areas around the chin. 

The bird on the picture resembles the jizz of Kermadec Petrel; colour features such as the contrasting lighter face area and whitish panel on the underwing are also present. In dorsal view it is possible to see that the shafts are dark coloured, hence we suppose this could be a potential Providence Petrel (Pterodroma solandri).

It would be very interesting to hear the comments of sea birders with at-sea experience with both Providence and Henderson petrels in order to establish the proper identification of this particular bird.