Date: 7/10/20 11:20 pm From: Jerry Tangren <kloshewoods...> Subject: [obol] Re: Black Storm-Petrel
Yes, I was putting more thought into the two Farallon Island records than anything else. Thank you for responding...
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From: Torrey G-T <tgagetomlinson...>
Sent: Friday, July 10, 2020 11:16:35 PM
To: Jerry Tangren <kloshewoods...>
Cc: <obol...> <obol...>
Subject: Re: Black Storm-Petrel
I did not initially consider Tristram’s but did briefly look over it when considering what other species this bird could have been. As far as I know, and according to ORBC and eBird, there aren’t any records of Tristram’s in Oregon. Tristram’s has a more pronounced pale carpal bar and less direct flight than Black. As far as exotic Storm-Petrels go, my Harrison’s Seabirds guide says Markham’s Storm-Petrel is most similar, though that’s a pipe dream of a rarity anywhere in the US.
On Jul 10, 2020, at 10:12 PM, Jerry Tangren <kloshewoods...> wrote:
Wow! Did you consider Tristram’s storm-petrel? It would be just as likely off the Oregon coast as a black.
After returning home and doing research on Storm-Petrels, a family I have limited experience with, I’ve come to the conclusion that the dark rumped Storm-Petrel John Sullivan and I saw earlier today was a Black Storm-Petrel. Below is my description on eBird of the bird, and the link to the checklist.
I initially saw this bird around 9:30 AM. It was very close to shore (~50-100 yards offshore), among the second or third set of breakers and flying northwest. I immediately realized that I was looking at a Storm-Petrel, an extraordinary bird this close to shore in any case. After the bird had flown maybe about 200 yards northeast and was just beyond the breakers, John was able to get on it and we followed it as it flew off t o the north about half a mile out before it disappeared.
One would normally expect Fork-tailed Storm-Petrel at this location, but I quickly realized that it was much darker than Fork-tailed Storm-Petrel, which I've seen a number of times. At this point I began noting the fieldmarks of the bird instead of trying to identify a specific species, as I have little Storm-Petrel experience beyond Fork-tailed. I have seen Ashy, Black and Wilson's once on a pelagic out of San Luis Obispo county, but I'm not familiar with any of these species.
The most obvious fieldmark on this bird was the completely dark rump and back. The carpal bar was not prominent as it would be on a Leach's or Wilson's Storm-Petrel—not to mention the white rump that is obvious on Wilson's and most Leach's Storm-Petrel. I didn't see it close enough to discern any color difference that would determine between Ashy and Black. Most notable was the lack of pale coloring that stood out on the back and the dor sal side of the wings. This bird had a methodical, consistent wingbeat that resulted in a smooth and direct flight, unlike the shallow erratic flight of Ashy or springy Nighthawk-like flight of Leach's. It dropped down in the water for no more than several seconds about three times as it flew along. At this point it had flown too far to observe it down in the water. When it was approximately a quarter mile offshore, it briefly flew among a flock of Red-necked Phalarope, which provided a good point of reference. This Storm-Petrel had noticeably longer wings than the Phalarope (which have a wingspan of 15 inches, ASSP wingspan of 18 inches, LESP 20 and BLSP 22).
These fieldmarks led us to the conclusion that this bird was most likely a Black Storm-Petrel. However, both John and I were hesitant to call it before we had done research beyond what we were capable of doing on phones with spotty coverage. After reading several in depth descriptions of Black, Ashy and Leach's Storm-Pe trels, and viewing images and videos of all three in flight, I concluded that this bird was indeed a Black Storm-Petrel.
*It should be noted that a large percentage of Leach's Storm-Petrel that breed on Isla Coronado, Isla de San Benito and Isla Guadalupe off the coast of Baja California exhibit predominantly dark rumps compared to the light rumped population in the Northern Pacific and Atlantic Oceans (Ainley, 1980). It would seem an even rarer occurrence to see a dark rumped Leach's Storm-Petrel off the Oregon coast than it would a Black Storm-Petrel. However, I imagine that the distribution of dark rumped Leach's Storm-Petrels is likely not something that has been extensively researched and is, needless to say, not a top priority in the ornithological community. This being said, I eliminated this species based off of the smooth flight pattern of BLSP and the obvious carpal bar present in LESP that was lacking in this bird.
I will submit to ORBC. This is the 7th stat e record, should it be accepted.