Monday, October 29, 2012

Band-Rumped Storm-Petrel and other goodies from Hurricane Irene...

As many folks hunker down to weather Hurricane Sandy, a different breed of people, "Storm Birders" as I like to call them, lick their chops at the thoughts of rarities blown off course with a chance at seeing them.  The following article is a look back at Storm Birding during Hurricane Irene.  It was written by Shai Mitra (with some minor changes by me, only to avoid any "situations" for future birding in such weather conditions) for NYSARC (New York State Avian Records Committee) in submitting a report documenting the incredible find of a Band-rumped Storm-Petrel at Jones Beach inlet during Hurricane Irene.

This was my first experience of hurricane birding and I count myself very, very fortunate to share this experience with the best of the best in NY.  Shai very generously offered to share his report for the blog as I wanted someone's perspective other than mine's for what remains as one of my most memorable birding experiences! I hope you enjoy the read. Observers: Shai Mitra, Patricia Lindsay, Tom Burke, Gail Benson, Doug Futumya, Steve Walter, Seth Asubel, Andy Guthrie, C.Finger and I (Andrew Baksh).

Storm Birding SWAT Team!!

BACKGROUND ON THE CIRCUMSTANCES OF THE OBSERVATIONS: Patricia Lindsay and I, (Shai Mitra), had driven back to Long Island from New England on Saturday night, as Tropical Storm Irene approached. We made it home safely and lifted a toast as we watched the weather and planned for a day of storm birding: both of us named Leach’s Storm-Petrel and Bridled Tern as the species we most hoped to see. The former was a true nemesis for both of us, occurring far more frequently in our Long Island-Rhode Island haunts than any other species we had never seen. The latter was a bird Patricia had seen just once on Long Island and which I had never seen in the ABA area (we’ve both seen many in the Caribbean).

The storm began to hit hard during the early morning hours on Sunday, but I noted that no weather stations anywhere between Nantucket and Cape May were recording sustained winds much over 50 mph. We set out, dodged downed trees and flooded roads, checked a few places in Bay Shore, and arrived on the barrier beach around 8:45 am. Traveling westward, we observed hundreds of shorebirds along the roadsides and several notable birds displaced by the storm: a Black Tern being blown backwards across Fire Island Inlet and overland; an adult Caspian Tern resting on the roadside near Captree; and then a stunning sight: an adult Bridled Tern resting on the roadside at West Gilgo. We turned around, snapped some photos, then turned again to resume our westward progress. As we did so, Patricia asked me to remind her how a Sooty Tern’s face pattern would compare to that of the Bridled we had just seen. As I began to explain, I hit the brakes, pointed to the roadside, and said, “In fact, it would look just like that!” An adult Sooty Tern was resting just feet away, a little east of the rotary. Soon after this, we found an adult Sandwich Tern resting in one of the Jones Beach parking lots. We reported all of these birds to Andrew Baksh, Tom Burke and party, and Doug Futuyma.

Arriving at Jones Beach, which was not signed or blocked off at the time, we checked the inlet side first, then the ocean side, seeing a variety of shorebirds, gulls, and terns. Returning to the inlet side, we positioned the car so that Patricia could scope from within the car, and I got out and began scoping from behind the shelter of a building. Although separated by only a couple of dozen feet, we couldn’t hear each other through the wind and used our cell phones to confirm that each was aware of an immature Sandwich Tern resting on the grass. At this time I received a call from Steve Walter, who eventually joined us.
First encounter As Steve joined me by the building with his binoculars and camera, Patricia got out of the car to speak with us, carrying only her binoculars. The wind had dropped noticeably but still was such that doors and tailgates required not so much manipulation as man-handling, discouraging her from retrieving her tripod. A little scope-eyed already, I offered her the use of my scope. This was a calculated move on my part, not merely a generous gesture, and it quickly yielded the desired effect as she called out, “I’ve got a Black Tern—no, it’s a storm-petrel!” Mindful of the wind, I used a very loud voice and coarse language to suggest that she keep the bird in view and soak in everything she could see on it while I fetched her scope. To myself I thought, “At last!” Returning with Patricia’s scope, I implored her not to take her eye off the bird but to explain where it was. The bird was to the northeast and not very far out in the inlet, and she got me on it very quickly. [see descriptive section below, under “FE”] During this first encounter, I detected an adult Bridled Tern in my scope field and alerted Patricia and Steve. The tern’s face pattern and pale collar were readily apparent, excluding Sooty Tern. Because of this, and because we had already photographed a Bridled Tern that morning, I thought it best to continue studying the storm-petrel. I didn’t record and I don’t recall now whether I lost sight of the storm-petrel or eventually decided to work on the tern, but I remember that neither of these two birds were in sight when Doug Futuyma arrived. I also remember thinking at that time that both the tern and the storm-petrel might still be present.  

Second encounter With Doug now joining us, and Steve equipped with his scope, we continued scanning the inlet. It was not long before we again detected a long-winged storm-petrel and studied it moving up and down the inlet. This encounter was not as long as the first, nor did the bird approach as closely. Thus, there were fewer occasions on which it showed its shape and plumage patterns from the most favorable angles, and even these were somewhat farther away. [see descriptive section below, under “SE”] Eventually, we saw it fly far to the left (west) and thought that it likely left the inlet. Once again, we were left with an empty inlet and a lot of explaining to do when more of our friends arrived: Seth Ausubel, Andrew Baksh, Gail Benson, Tom Burke, C. Finger, and Andy Guthrie.  

Third encounter More eyes make for better searching, and it wasn’t long before more storm birds were found. I believe it was Patricia who picked up a long-winged storm-petrel for a third encounter. Everyone got on the bird, and it was carefully scrutinized.  

Leach’s Storm-Petrel Some time after the third encounter, Patricia picked up another long-winged storm-petrel, and Andy Guthrie and I got on it quickly (others were watching a Bridled Tern at this time). Andy exclaimed, “I’m sure this is a Leach’s!”—and, indeed, it readily showed multiple features indicative of this species. [see descriptive section under “Leach’s”] Description of Band-rumped Storm-Petrel

FE: Looking through Patricia’s scope, I saw, as I had hoped, a small dark seabird with a white rump patch and long wings—obviously much longer than those of the familiar Wilson’s Storm-Petrel. In particular, the inner part of the wing, which appears notably and distinctively short on Wilson’s, was conspicuously longer on this bird, just as I had hoped. But this bird’s rump patch was not at all as I expected to see on a Leach’s: it was bright white and strap-shaped, wider from side to side than from fore to aft, and with very neat edges perpendicular to the bird’s long axis. –And this bird’s tail was not at all as I expected to see on a Leach’s either: the rear edge of the tail appeared straight, not forked, on a very good view. A bit stunned, I called out to my companions, “It’s a Band-rump.”

Patricia and I carefully studied the rump patch and tail shape and verified them under a variety of angles. To me, the strap-like rump patch looked like a short, wide rectangle, and I clearly saw the leading (anterior) edge as a neat line crossing the body just beyond the wings and curving very slightly forward at the sides. Where it crossed the middle of the body, this line appeared straight and perpendicular to the body’s long axis. The rear edge also looked neat and parallel to the front edge, and the white feathering did not extend markedly onto the undertail, as it does in Wilson’s Storm-Petrel. Patricia was able to discern that the white “wrapped around a little” onto the sides of the undertail (her words at the time), but explicitly noted that the white in this area was much less extensive than in Wilson’s. We plainly saw that the tail was not forked during several very favorable views, where the bird banked and showed its spread tail. On these occasions, the tail looked to me like a black trapezoid, about as long from rump patch to tip as it was broad at the tip (but slightly narrower at the base). Compared to the familiar Wilson’s Storm-Petrel, the bird’s tail looked longer and the white rump patch shorter, fore to aft.

As we studied the bird, patiently awaiting the best opportunities to assess and reassess the characters described above, we noted as many features as we could. For instance, the bird appeared really black, not brown, and showed only a subtle hint of paler gray on the upper surfaces of the inner wings. When the bird banked, its upperparts appeared almost uniformly black, except for the bold white rump band and the subtly paler carpal areas. The back itself looked as dark as the dark parts of the wings, i.e., black. Its feet never protruded visibly beyond the tail, even on a couple of occasions when I’d expect this feature to be visible on a Wilson’s.

Its flight style varied depending on its direction in relation to the wind. Being unfamiliar with both Band-rumped and Leach’s, I doubted I’d be able to make useful distinctions regarding its flight, but I noted that the bird often glided on flat wings, slightly bowed-down at the wrists, recalling a tiny shearwater, especially when it was flying into the wind. Sometimes it flapped more deeply, but even here its flight appeared relatively direct, lacked the fluttery quality characteristic of Wilson’s, and could not be described as erratic, as that of Leach’s often is.  

SE: During the second encounter, we took pains to examine all of the characters noted during the first encounter. In the case of each, the bird appeared basically similar to the bird seen during the first encounter. It is true that all of these features were more difficult to assess during this briefer and slightly more distant encounter, but we did our best, and I could not discern any feature counter-indicative of Band-rumped or indicative of Leach’s—which, it may be worth noting, I still keenly hoped to see. An important feature to note here is that Patricia explicitly recorded the square tail tip during this encounter, and we both perceived the bird’s flight style and behavior as very similar to what we had observed during the first encounter.  

TE: My notes and recollections of the third encounter are less detailed than those from the first encounter, but more detailed than those from the second encounter. The bird was more distant than during the first encounter but clearly showed the long wings of an Oceanodroma. I explicitly noted its black body plumage, the absence of bold, buffy carpal bars, and its shearwater-like flight, arcing on bowed wings. Patricia noted that she saw the tail shape well and that it was square-shaped, as in our earlier views. She also noted that it presented the “same aspect” as the Band-rump seen earlier. My notes also include the phrase, “rump patch?”—the question mark indicating my uncertainty regarding how well this feature was seen during this encounter.

The other observers expressed similar impressions and conclusions, and I don’t recall that anyone described seeing any features counter-indicative of Band-rumped or specifically suggestive of Leach’s. Andy Guthrie expressed some uncertainty in the identification as Band-rumped, which I attributed more to a careful and cautious approach than to any specific insight that the bird was a Leach’s. The third encounter was more prolonged than the second, with some views closer, but even the best views here were less favorable than the best ones obtained during the first encounter.  

Leach’s: This bird showed extensive, bold, and buff-colored carpal patches; a definitely browner body color (its back was browner and paler than the black of the wingtips); a dingy white, triangular rump patch appearing longer fore to aft than side to side; and a distinctly forked tail. Furthermore, this bird appeared much more apt than those seen earlier to lift its wings to the wind and be swept abruptly up the inlet. On our best views, we were able to discern a dark median streak through the rump patch.

HOW IDENTIFICATION WAS DETERMINED: We understood that identifying a Band-rumped Storm-Petrel on Long Island was a very difficult matter requiring considerable care. The first step involved excluding the two storm-petrel species that occur regularly in NYS, Wilson’s and Leach’s. The second step involved assessing multiple characters specific to Band-rumped Storm-Petrel, as opposed to other potentially extralimital species.  

Wilson’s Storm-Petrel is a very familiar species I’ve studied closely, both from land and at sea, over the course of more than 30 years. I’ve studied these birds under a wide range of weather conditions, including wind speeds higher than those we experienced on the 28th, and I’ve critically assessed its structure and flight on many occasions, for instance in relation to those of Black-bellied Storm-Petrel, whose jizz I think resembles Wilson’s more closely than do those of Band-rumped or Leach’s. Wilson’s Storm-Petrel was readily excluded during all three encounters because the focal bird(s) clearly showed longer wings, particularly the portions of the wings proximal to the wrists. I have carefully studied many thousands of Wilson’s (often while searching for Leach’s) and learned the appearance of their wings in different postures and flight styles, and I was completely satisfied that Wilson’s could never impart the consistently long-winged impression given by the bird(s) under consideration. Beyond this, I would expect the long legs, the extensively white undertail, and the distinctive fluttery flight of Wilson’s to be visible during the encounters described above; these were looked for and their absence confidently recorded. Finally, we also saw several Wilson’s Storm-Petrels that day, and these presented their field marks quite unambiguously.

As noted above, Leach’s Storm-Petrel was a true nemesis of mine—a species I had sought for decades unsuccessfully on- and offshore from Rhode Island and Long Island. Thus, although I could claim no previous field experience with it, it is a bird I had researched very thoroughly and whose field marks I knew from innumerable written sources, photographs, and even some videos. This was the species that I most hoped to see that day and that I expected to see when Patricia announced she had a storm-petrel that had momentarily given her the impression of a Black Tern (the latter being a species we encountered repeatedly that day). In this context, it is also worth stating that I was completely unaware of the Band-rumps reported by P. A. Buckley, Dick Veit, and Vernon Laux that day until after all of the encounters described above. I was aware that a Band-rump had been reported from Connecticut early in the morning, but I knew no details about the observation and regarded with considerable skepticism at the time.

Finally, I was keenly conscious that Leach’s Storm-Petrel is decidedly the most likely storm-petrel species to be driven ashore in our region during late summer and fall storms—more so than even Wilson’s Storm-Petrel. As a post-script in this regard, Dick Veit, on Tuckernuck Island, recorded about 20 Leach’s, but just a single Wilson’s, during Irene. Thus, although I was consciously hoping for and intellectually expecting Leach’s, I nevertheless recognized that the bird I was looking at showed multiple features counter-indicative of that species. In this regard, it is worth re-considering how well each feature was assessed, and to compare these assessments with those we were ultimately fortunate enough to obtain for Leach’s Storm-Petrel.

Our best views of the Band-rump (e.g., during the first encounter) were at least as good as our best views of the Leach’s. Thus, we consistently noted a squared tail shape on the former under circumstances at least as favorable as those during which the latter’s forked tail shape was very conspicuous. The same rationale is true for the rump patch, whose boldness and shape Patricia and I plainly saw in good detail during our best views, whereas the Leach’s rump patch was often difficult to see at all under poor views and looked markedly different than the Band-rump’s during good views. Ditto for the body plumage, which, on the Band-rump, appeared consistently black (as black on the back as on the wingtips); and for the carpal patches, which appeared small and dull gray on the Band-rump under views comparable to those when the Leach’s bold, buffy patches were obvious. Finally, it is also true that in our studies of the focal bird(s)’s flight style, we looked for signs of “erratic, nighthawk-like flight” but saw nothing in that regard until we had an actual Leach’s in view, at which time we did notice a few violent veers and sweeps. For all of these reasons, I think Leach’s Storm-Petrel can be excluded.

In every respect in which the focal bird(s) deviated from the appearance of Leach’s Storm-Petrel, it matched that of Band-rumped. The only discernible way in which the focal bird did not conform with descriptions of Band-rump with which I was aware at the time was that I could never perceive any signs of molt among its flight feathers—described by some authors as being frequent during the summer in the Gulf Stream. Even so, I learned subsequently that the populations most likely to occur in the western North Atlantic frequently look “clean-winged” by late summer. An area of real uncertainty involves the number of individuals involved. As noted above, it was our impression that the first and second encounters involved the same individual, and that this individual left the inlet. I am not at all sure that either of these impressions was correct, and it is quite possible that just a single Band-rump was involved. In reviewing what we saw in each encounter, the differences in quality among the various encounters are worth considering. The first Band-rump encounter definitely yielded more good looks at the bird’s upperparts facing us at favorable angles than did the second and third. I think this was partly a function of closer distance and longer duration, but possibly also a function of changing wind direction (the wind had been southeasterly when strongest, at Captree around 8:45, then had proceeded to go southerly then southwesterly while diminishing in speed, then roaring back out of the northwest).

In any case, the strongest evidence favoring Band-rumped Storm-Petrel was definitely recorded during the first encounter, when Patricia and I both recorded very detailed impressions of the shape and outline of the rump patch, and when Patricia even noticed the slight “wrapping around” onto the undertail. The details and quality of these impressions, along with those of the tail shape, back color, carpal patch color and extent, etc. make me confident in identifying this bird as a Band-rumped Storm-Petrel. I believe that the second and third encounters also involved this species, but I must admit to being somewhat less confident here. For one thing, my original notes lack detailed, explicit assessments of the rump patch from these encounters; for another, it must be admitted that the balance of expectation might have shifted somewhat after the initial, highly convincing, Band-rump encounter. Even so, I still believe that we were able to judge tail shape, body color, carpal patch, and rump patch well enough to exclude Leach’s in the latter two encounters.

As a final note, it should be emphasized that Irene produced what was probably an unprecedented number of Gulf Stream birds in our region (New Jersey, New York, and southern New England). Irene produced multiple Black-capped Petrels, 10 or more White-tailed Tropicbirds, and unprecedented numbers of Bridled Terns. In this respect Irene was very different from all prior “productive” hurricanes I’ve birded, going back to 1996 (Bertha in mid July and two more in early September), Floyd in 1999, and Ernesto in 2006. All of these storms produced Sooty Terns but few or no examples of the Gulf Stream species so prominent during Irene. In this context, the multiple reports of Band-rumped Storm-Petrels during Irene (including one photographed in the hand and flying off after release on Nantucket, apart from Veit’s Tuckernuck bird), appear less improbable in retrospect than they did that day, before our astonished eyes. Share with Bookmark and Share

1 comment:

Leonor Chavez said...

Hello Andre, today I went to JBWR to check the extend of the damage cause by the storm, and I can't believe what I saw. The West Pond Trail has been cut in two. The Bay and The West Pond are now connected by a river!! It's is unreal. The trails have taken a severe beating. Trees down, vegetation thrown everywhere, I can't beging to tell you how devastating it all looks. As I was walking back to the parking lot, which by the way, was filled with parked cars, I found a small injured Diamond-backed Terrapin turtle. I'm caring for it the best I can, and tomorrow I will take it to the vet. I hope you are OK, take care please. I am going to ask the rangers at the refuge if need volunteers to help them with the clean-up and rebuild of the will take time, but it will come back.