ML606169661

Age

Not specified

Sex

Not specified

Media notes

The 5th and closest bird of the day. Also in the best light.

Observation details

Wow. First county records that were dropped off by Hilary (pending CBRC acceptance). Birds were first viewed at 7:09, 7:26, 7:37, 7:47, and 9:53. The first bird was initially spotted by Loren Wright and called out as a white-rumped bird to the north before it was close enough to photograph or identify. This first county record was also observed by Tom Wurster, Sylvia Afable, Jill Dale, and myself. All five of these birds were initially spotted to the north and followed as they approached the pier before continuing to move south and away. This along with the visible difference in the extent of white on the rump and various amounts of feather damage between the birds allowed all observers to reach the conclusion that they were all different birds and not repeats. These Storm-Petrels were often viewed directly alongside LESP and in direct comparison were maybe a smidge larger, but overall very similar in size. The wings appeared more pointed as well as the tail being a little more slender. Flight style was also slightly different, being overall slightly more bounding and less fluttery than the Leasts they were often with (although not nearly as much so as something like a Black Storm-Petrel). The most striking feature about these birds was their strikingly large white rumps, which covered, depending on the bird and angle of the photo, covered about 60%-70% of the tails, which is consistent with the Peruvian (kelalli) ssp. There was some confusion initially as apparently the Galapagos ssp. (tethys) is often illustrated in North American field guides, which shows much more like 80-90% white. This white also wrapped around to varying degrees to the sides. Some of the birds (especially bird 1) had somewhat of a limited dark line running up the center (Apparently this seems to be a feature of birds that are more worn). When seen from above these birds had fairly weak carpal bars that did not extend fully to the leading edge of the wing. The bills also seemed quite heavy for a Storm-Petrel. Similar Species: Townsend's Storm-Petrel is likely the biggest confusion species, given that they have a similar size, structure, and rump to a Wedge-rumped. TOSP shows less white on the rump, with individuals averaging about 50% of the tail length (unlike 60-70% on the birds we saw). The bill of Townsend's Storm-Petrel is also much slimmer than that of a Wedge-rumped, which we had close enough views on a decent handful of individuals to see this. Townsend's should also be quite a bit larger than the birds we viewed, which seemed if anything only a hair larger than LESP. Townsend's Carpal bar is more pale and also reaches the leading edge of the wing, unlike any of the birds we viewed. Leach's Storm-Petrel would not show nearly as much white on the rump even in the most white-rumped individuals. This white also wouldn't wrap around to the sides. The carpal bar should be much more pronounced and along with the dark primaries would give a much more contrasty look to the bird when viewed from the top. Leach's also would show a much more deeply forked tail unlike the shallow notch on our bird. Also, it's worth adding that as I write this there have been probably 50-70 known WRSP displaced by the storm and no known TOSP. Expert consensus on these birds by Alvaro Jaramillo, Paul Lehman, and others seems to point towards this species.

Technical information

Model

ILCE-6000

Lens

FE 200-600mm F5.6-6.3 G OSS

ISO

800

Focal length

600 mm

Flash

Flash did not fire

f-stop

f/6.3

Shutter speed

1/1600 sec

Dimensions

2361 pixels x 1612 pixels

Original file size

2.04 MB