Greeings all,
After spending nearly two hours yesterday with Fork-tailed Storm-Petrels almost
constantly in my scope, I echo Jay Withgott's cautionary commentary about the
variability in appearance of this species. In my zeal to see my first Ashy
Storm-Petrel in Oregon, I latched on to a couple worn and considerably darker
Fork-taileds and had to watch them for several seconds before positively
identifying them as such. I remarked aloud a couple times to others gathered at
Boiler Bay yesterday that I was surprised by how variable the Fork-taileds
were. Most of the Fork-taileds that I seen have been from boats, where lengthy
scope studies of individual birds don't happen. This was by far my best
experience with this species in terms of studying individual difference. On
many birds the wings looked almost uniformly dark above, with very little
contrast between the dark coverts and lead edge of the wing and the rest of the
wing. Also, many the amount of contrast between the dark underwing linings and
the much paler undersides of the flight feathers was greatly reduced. On many
individuals the head and underparts looked considerably darker and it was near
impossible to make out the dark patch around the eye.
Once we saw an actual Ashy Storm-Petrel it was noticeably darker than even the
darkest Fork-taileds and its flight style and proportions were quite different.
It looked straighter-winged, longer-tailed, slightly smaller, and slighter
bodied in direct comparison. The flight was characterized by what I would
describe as a stiff-winged flutter that was unlike the more languid wingbeats
of the Fork-taileds.
It was fun, although exhausting to make the nearly four-hour round trip for
just two hours of birding (had to go to work). I could have spent all day at
Boiler Bay yesterday just watching storm-petrels. I do wonder about the
reported counts. As Phil Pickering posted yesterday this seems to be a
localized event and the birds that I was watching weren't flying by or on the
move. I watched many birds making small loops as they fed through the same
areas flying into the southwesterly winds. I wonder if some birds were being
double and triple counted as they made repeated passes by our various viewing
stations. I saw just two Ashy Storm-Petrels yesterday and I felt those could be
individually identified by varying amount of light coloration in the upperwing
coverts.
Dave Irons
