Unknown all-dark Pacific shearwater

First four photos are of Wedge-tailed Shearwaters for comparison. The first photo is by Juan Pablo Elizondo taken on April 2 on a Golfito, Costa Rica trip. The other three photos (with water background) were taken by Bruce MacTavish during his March 20 to April 16, 2008 trip off Costa Rica and Nicaragua.

The final five photos are of the mystery shearwater originally thought to be a Short-tailed Shearwater. Identification presently not known. All photos are of the same individual taken on March 29, 2008. The following are data for the sightings of similar birds. Photos and observations by Bruce MacTavish.

• 1 on 21 March at about 25 km south of southern tip of Nicoya Peninsula.
• 2 on 29 March. The attached photos were taken about 60 km offshore at N 8°59.95’, W 84°44.24’.
• 4 on 30 March atN 8°46.121’, W 84°23.943’ about 50 km west of Osa Peninsula with 75 Wedge-tailed Shearwaters feeding around a group of 75 Common Dolphins.
• 1 on 1 April at about 100 km SE of Osa Peninsula.

We are seeking comments from seabird experts (there is some discussion at http://groups.google.com/group/Seabird-News/browse_thread/thread/b34a6413fd338523?hl=en ) and will update when a decision is made about the identification of this bird.