Re: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island
Shai, Thank you for the dive into your bookshelves. For those who are away from the libraries :), or don’t have back issues of North American Birds, you can go to the SORA site (Searchable Ornithological Research Archive) maintained by the University of New Mexico (sora.unm.edu). Many ornithological journals, including North American Birds are available there as pdfs. The issue Shai cites is among them and the bird in question is also discussed in the Seasonal Highlights section, as well as a color photo in the Pictorial Highlights section as well as the page Shai references. Joe DiCostanzo Sent from my iPad > On Jun 15, 2018, at 3:12 PM, Shaibal Mitra wrote: > > Swore I wouldn't do it, but I just pulled my stacks of North American Birds > off the shelf. > > The NJ bird was photographed at Stone Harbor, near Cape May, by Michael > O'Brien on 14 Jul 2003, and reproduced in Volume 57, p. 473 of North American > Birds. The caption reads, "One of the most interesting birds of the season to > be documented in the [Hudson-Delaware] Region, indeed one of the most > intriguing in many years, was the apparent longipennis Common Tern, a > Siberian nester never before recorded in the Atlantic basin, which was > studied carefully at Stone Harbor Pt. 14 Jul (ph. MO'B, m/ ob.). Old World > authorities have reviewed the series of photographs by O'Brien and concur > with the identification as longipennis, probably a bird in its second summer." > > The RI bird was around that time, and it is possible that I conflated it with > the NJ bird vis a vis the NAB photo, but I've put in the call to an observer > of that bird (which was definitely well photographed) to pin it down, too. > > Shai > > From: Shaibal Mitra > Sent: Friday, June 15, 2018 2:23 PM > To: NYSBIRDS (NYSBIRDS-L@cornell.edu) > Subject: RE: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island > > Again, nobody is saying we know for sure what these birds are. But those who > know the most about the records in question find them intriguing, and, having > studied variation in hirundo collectively with great interest for many > decades, remain uncomfortable with that null hypothesis. Another hypothesis > that people have offered is hirundo x Arctic Tern hybrid; genetic > incompatibility might result in deviations in various traits associated with > normal breeding condition. Another possibility (which could account for the > oddity that most/all have been "second-summer types" (based on white in the > forehead, mottling on the underparts, and atypical primary replacement > pattern) is that just a couple of birds have been rattling up and down the > Atlantic and have gotten old and lonely. > > The cool thing about the better candidates is that they would absolutely > stand out from hirundo in multiple ways, even if their bills and legs were > colored exactly like typical hirundo: > > They are long-winged--as judged relative to their bodies, resembling Arctic > Tern in this way > They are very long-tailed--at least one with tail streamers extending beyond > the tips of their already relatively long wings > They are intensely gray below--more intensely gray than even high breeding > hirundo; this is especially notable on second-summer types, because > second-summer type hirundo tend to be less intensely gray than even dull > breeding adult hirundo > They have shorter, subtly different shaped bills than typical > hirundo--obviously just a supporting character, easily matched by variant > hirundo, but interesting because supposedly typical of longipennis > > Their dark bills catch the eye but as Joe noted are not that exceptional for > hirundo, even in June. In contrast, their dark legs are vastly more unusual > at this date. In my experience, dark legs are extremely rare among hirundo in > May-June, even within each of the odd-ball categories: adults that arrive > with dark bills, second-summer types, and first-summers. > > Getting back to the question at hand, yes, there have been carefully > scrutinized, documented, and published longipennis candidates from NJ, LI, > RI, and MA (I recall less clearly one from the UKin this time frame also). I > have collected (but not assembled and analyzed) the particulars on these over > the years. The place to look for the best information is not eBird or other > online sites, but rather North American Birds, the relevant state > publications, and the original documents, photos, and correspondence I've > archived (and promise some day to publish). > > The first one I remember was from Rhode Island; it was photographed and > published in North American B
RE: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island
Swore I wouldn't do it, but I just pulled my stacks of North American Birds off the shelf. The NJ bird was photographed at Stone Harbor, near Cape May, by Michael O'Brien on 14 Jul 2003, and reproduced in Volume 57, p. 473 of North American Birds. The caption reads, "One of the most interesting birds of the season to be documented in the [Hudson-Delaware] Region, indeed one of the most intriguing in many years, was the apparent longipennis Common Tern, a Siberian nester never before recorded in the Atlantic basin, which was studied carefully at Stone Harbor Pt. 14 Jul (ph. MO'B, m/ ob.). Old World authorities have reviewed the series of photographs by O'Brien and concur with the identification as longipennis, probably a bird in its second summer." The RI bird was around that time, and it is possible that I conflated it with the NJ bird vis a vis the NAB photo, but I've put in the call to an observer of that bird (which was definitely well photographed) to pin it down, too. Shai From: Shaibal Mitra Sent: Friday, June 15, 2018 2:23 PM To: NYSBIRDS (NYSBIRDS-L@cornell.edu) Subject: RE: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island Again, nobody is saying we know for sure what these birds are. But those who know the most about the records in question find them intriguing, and, having studied variation in hirundo collectively with great interest for many decades, remain uncomfortable with that null hypothesis. Another hypothesis that people have offered is hirundo x Arctic Tern hybrid; genetic incompatibility might result in deviations in various traits associated with normal breeding condition. Another possibility (which could account for the oddity that most/all have been "second-summer types" (based on white in the forehead, mottling on the underparts, and atypical primary replacement pattern) is that just a couple of birds have been rattling up and down the Atlantic and have gotten old and lonely. The cool thing about the better candidates is that they would absolutely stand out from hirundo in multiple ways, even if their bills and legs were colored exactly like typical hirundo: They are long-winged--as judged relative to their bodies, resembling Arctic Tern in this way They are very long-tailed--at least one with tail streamers extending beyond the tips of their already relatively long wings They are intensely gray below--more intensely gray than even high breeding hirundo; this is especially notable on second-summer types, because second-summer type hirundo tend to be less intensely gray than even dull breeding adult hirundo They have shorter, subtly different shaped bills than typical hirundo--obviously just a supporting character, easily matched by variant hirundo, but interesting because supposedly typical of longipennis Their dark bills catch the eye but as Joe noted are not that exceptional for hirundo, even in June. In contrast, their dark legs are vastly more unusual at this date. In my experience, dark legs are extremely rare among hirundo in May-June, even within each of the odd-ball categories: adults that arrive with dark bills, second-summer types, and first-summers. Getting back to the question at hand, yes, there have been carefully scrutinized, documented, and published longipennis candidates from NJ, LI, RI, and MA (I recall less clearly one from the UKin this time frame also). I have collected (but not assembled and analyzed) the particulars on these over the years. The place to look for the best information is not eBird or other online sites, but rather North American Birds, the relevant state publications, and the original documents, photos, and correspondence I've archived (and promise some day to publish). The first one I remember was from Rhode Island; it was photographed and published in North American Birds. The issues are right there on my shelf, but I don't have time or interest to search right now. This was earlier, I think, than one from NJ in 2003. Another was studied and photographed by Scott Whittle and me at Moriches Inlet in June 2009. 2011 brought not only the LI bird we've been discussing, but another at Muskeget Island, off Nantucket, studied by Vern Laux and photographed by Peter Trimble. >From an email from Dick Veit: "Factors distinguishing this [Muskeget] bird >from other terns include (aside from the blackish bill) reddish brown legs, >upperparts darker gray than local common terns, bill rather short, head more >rounded, rather "domed", underparts darkish gray (though not as dark as they >would be in May), tail feathers longer than wingtips at rest, legs seemed >slightly shorter than commons, though not as short as on arctic." All this typing is cramping my scope-focusing hand. I think I might just head down to an inlet, any inlet! Best
RE: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island
Again, nobody is saying we know for sure what these birds are. But those who know the most about the records in question find them intriguing, and, having studied variation in hirundo collectively with great interest for many decades, remain uncomfortable with that null hypothesis. Another hypothesis that people have offered is hirundo x Arctic Tern hybrid; genetic incompatibility might result in deviations in various traits associated with normal breeding condition. Another possibility (which could account for the oddity that most/all have been "second-summer types" (based on white in the forehead, mottling on the underparts, and atypical primary replacement pattern) is that just a couple of birds have been rattling up and down the Atlantic and have gotten old and lonely. The cool thing about the better candidates is that they would absolutely stand out from hirundo in multiple ways, even if their bills and legs were colored exactly like typical hirundo: They are long-winged--as judged relative to their bodies, resembling Arctic Tern in this way They are very long-tailed--at least one with tail streamers extending beyond the tips of their already relatively long wings They are intensely gray below--more intensely gray than even high breeding hirundo; this is especially notable on second-summer types, because second-summer type hirundo tend to be less intensely gray than even dull breeding adult hirundo They have shorter, subtly different shaped bills than typical hirundo--obviously just a supporting character, easily matched by variant hirundo, but interesting because supposedly typical of longipennis Their dark bills catch the eye but as Joe noted are not that exceptional for hirundo, even in June. In contrast, their dark legs are vastly more unusual at this date. In my experience, dark legs are extremely rare among hirundo in May-June, even within each of the odd-ball categories: adults that arrive with dark bills, second-summer types, and first-summers. Getting back to the question at hand, yes, there have been carefully scrutinized, documented, and published longipennis candidates from NJ, LI, RI, and MA (I recall less clearly one from the UKin this time frame also). I have collected (but not assembled and analyzed) the particulars on these over the years. The place to look for the best information is not eBird or other online sites, but rather North American Birds, the relevant state publications, and the original documents, photos, and correspondence I've archived (and promise some day to publish). The first one I remember was from Rhode Island; it was photographed and published in North American Birds. The issues are right there on my shelf, but I don't have time or interest to search right now. This was earlier, I think, than one from NJ in 2003. Another was studied and photographed by Scott Whittle and me at Moriches Inlet in June 2009. 2011 brought not only the LI bird we've been discussing, but another at Muskeget Island, off Nantucket, studied by Vern Laux and photographed by Peter Trimble. >From an email from Dick Veit: "Factors distinguishing this [Muskeget] bird >from other terns include (aside from the blackish bill) reddish brown legs, >upperparts darker gray than local common terns, bill rather short, head more >rounded, rather "domed", underparts darkish gray (though not as dark as they >would be in May), tail feathers longer than wingtips at rest, legs seemed >slightly shorter than commons, though not as short as on arctic." All this typing is cramping my scope-focusing hand. I think I might just head down to an inlet, any inlet! Best, Shai From: bounce-122640877-11143...@list.cornell.edu [bounce-122640877-11143...@list.cornell.edu] on behalf of Joseph DiCostanzo [jdic...@nyc.rr.com] Sent: Friday, June 15, 2018 1:31 PM To: Robert Lewis Cc: NYSBIRDS (NYSBIRDS-L@cornell.edu) Subject: Re: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island I went to the ABA’s Birding News site that lists RBA’s around the country and did a search for longipennis. For the months of May and June of this year, most of the returns of the search seemed to refer to a dragonfly with that scientific name. There was one bird report from the Aleutians and all other reports came from reports on Long Island related to this discussion. I also searched for Siberian Tern and got nothing. Joe DiCostanzo Sent from my iPad On Jun 15, 2018, at 11:44 AM, Robert Lewis mailto:rfer...@yahoo.com>> wrote: Perhaps I missed it, but there seems to be an obvious question here: have bids like this been reported from neighboring states? Bob Lewis Sleepy Hollow Y On Thursday, June 14, 2018, 10:49:25 AM EDT, Shaibal Mitra mailto:shaibal.mi...@csi.cuny.edu>> wrote: As I mentioned in my earlier note to the list on this subject (8 Jun 18, co
Re: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island
I went to the ABA’s Birding News site that lists RBA’s around the country and did a search for longipennis. For the months of May and June of this year, most of the returns of the search seemed to refer to a dragonfly with that scientific name. There was one bird report from the Aleutians and all other reports came from reports on Long Island related to this discussion. I also searched for Siberian Tern and got nothing. Joe DiCostanzo Sent from my iPad > On Jun 15, 2018, at 11:44 AM, Robert Lewis wrote: > > Perhaps I missed it, but there seems to be an obvious question here: have > bids like this been reported from neighboring states? > > Bob Lewis > Sleepy Hollow Y > > > On Thursday, June 14, 2018, 10:49:25 AM EDT, Shaibal Mitra > wrote: > > > As I mentioned in my earlier note to the list on this subject (8 Jun 18, > copied at the very end of the present note), the jury is certainly still out > on the status of longipennis Common Terns on the east coast. Joe's highly > informed contributions are a very welcome addition to the process and > underscore several areas to focus on in resolving the matter. First, it is > clearly true that to claim an extralimital longipennis, the evidence must be > very strong and include multiple characters beyond dark bills and dark legs. > I have a lot to contribute on this front, because I have made a point of > studying non-breeding terns for more than 20 years, during which time I have > collected detailed data on large samples of carefully scored first-summers > and "second-summer types" (a category which, as Joe notes, consists of an odd > amalgam of a subset of some but not all two year-olds, older adults short of > full breeding condition, and very old, senescent adults)--not only of Common > Terns, but also of Arctic, Roseate, Least, Black, and others. > > For now I just want to make two very simple points in response to the queries > Joe raises toward the end of his note. > > First, I'd like to address Joe's skepticism about judging wing length > visually. I once wrote a long, detailed note to the ID Frontiers list > defending the critical, visual assessment of shape (i.e., the relative sizes > of morphological structures; that piece concerned warblers, or maybe willets, > or maybe I did it separately for both?). I might be able to dig it/them up, > but for now I remember demonstrating that large samples of in-hand > measurements counter-intuitively often obscure real differences between > similar species, males and females, etc. The reason is that handbooks > over-emphasize extreme data, neglecting quantitative measures of variance and > covariance, and because most observers are unprepared or unwilling to think > quantitatively. At the same time, sharp-eyed birders can unerringly > distinguish Blackpoll and Pine Warblers at a glance by shape, even though > practically all their measurements, viewed individually in huge samples, > overlap. With regard to terns, I can recognize visually how the length of an > individual's primary projection compares to the chord of its dorsum with > enough precision to distinguish Common and Arctic Terns very confidently. So > I would caution against categorically dismissing this line of evidence. > > Second, the true statuses of non-breeding seabirds remain an amazing mystery, > and the few glimpses we've had so far have been really exciting. Most > obviously, the local status of Arctic Tern has been completely re-written in > the past 20 years based precisely on attention to loafing flocks of > non-breeding terns. Furthermore, scrutiny of these flocks has yielded many > other rarities, some of them as unexpected as longipennis might seem: Elegant > Tern, Cayenne Tern, acuflavidus Sandwich Terns during June, Little Gulls > during June, etc. My point is that although the improbability of longipennis > needs to be answered with strong evidence, much stranger things have > happened. I still examine every Arctic Tern I see with the remote potential > of Antarctic Tern in mind; the non-breeders hang out together down there, so > maybe a few stick together up here, too. Ditto for examining first-summer > Least Terns for Littles and first-summer Black Terns for White-winged and > Whiskered. > > Brian Patteson recently saw a Tahiti Petrel off of Hatteras! > > Shai Mitra > Bay Shore > > > ____ > From: bounce-122637763-11143...@list.cornell.edu > [bounce-122637763-11143...@list.cornell.edu] on behalf of Joseph DiCostanzo > [jdic...@nyc.rr.com] > Sent: Thursday, June 14, 2018 9:08 AM > To: Robert Lewis > Cc: nysbirds-l > Subject: Re: [nysbirds-l] Dark billed, dark
Re: RE: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island
Perhaps I missed it, but there seems to be an obvious question here: have bids like this been reported from neighboring states? Bob LewisSleepy Hollow Y On Thursday, June 14, 2018, 10:49:25 AM EDT, Shaibal Mitra wrote: As I mentioned in my earlier note to the list on this subject (8 Jun 18, copied at the very end of the present note), the jury is certainly still out on the status of longipennis Common Terns on the east coast. Joe's highly informed contributions are a very welcome addition to the process and underscore several areas to focus on in resolving the matter. First, it is clearly true that to claim an extralimital longipennis, the evidence must be very strong and include multiple characters beyond dark bills and dark legs. I have a lot to contribute on this front, because I have made a point of studying non-breeding terns for more than 20 years, during which time I have collected detailed data on large samples of carefully scored first-summers and "second-summer types" (a category which, as Joe notes, consists of an odd amalgam of a subset of some but not all two year-olds, older adults short of full breeding condition, and very old, senescent adults)--not only of Common Terns, but also of Arctic, Roseate, Least, Black, and others. For now I just want to make two very simple points in response to the queries Joe raises toward the end of his note. First, I'd like to address Joe's skepticism about judging wing length visually. I once wrote a long, detailed note to the ID Frontiers list defending the critical, visual assessment of shape (i.e., the relative sizes of morphological structures; that piece concerned warblers, or maybe willets, or maybe I did it separately for both?). I might be able to dig it/them up, but for now I remember demonstrating that large samples of in-hand measurements counter-intuitively often obscure real differences between similar species, males and females, etc. The reason is that handbooks over-emphasize extreme data, neglecting quantitative measures of variance and covariance, and because most observers are unprepared or unwilling to think quantitatively. At the same time, sharp-eyed birders can unerringly distinguish Blackpoll and Pine Warblers at a glance by shape, even though practically all their measurements, viewed individually in huge samples, overlap. With regard to terns, I can recognize visually how the length of an individual's primary projection compares to the chord of its dorsum with enough precision to distinguish Common and Arctic Terns very confidently. So I would caution against categorically dismissing this line of evidence. Second, the true statuses of non-breeding seabirds remain an amazing mystery, and the few glimpses we've had so far have been really exciting. Most obviously, the local status of Arctic Tern has been completely re-written in the past 20 years based precisely on attention to loafing flocks of non-breeding terns. Furthermore, scrutiny of these flocks has yielded many other rarities, some of them as unexpected as longipennis might seem: Elegant Tern, Cayenne Tern, acuflavidus Sandwich Terns during June, Little Gulls during June, etc. My point is that although the improbability of longipennis needs to be answered with strong evidence, much stranger things have happened. I still examine every Arctic Tern I see with the remote potential of Antarctic Tern in mind; the non-breeders hang out together down there, so maybe a few stick together up here, too. Ditto for examining first-summer Least Terns for Littles and first-summer Black Terns for White-winged and Whiskered. Brian Patteson recently saw a Tahiti Petrel off of Hatteras! Shai Mitra Bay Shore From: bounce-122637763-11143...@list.cornell.edu [bounce-122637763-11143...@list.cornell.edu] on behalf of Joseph DiCostanzo [jdic...@nyc.rr.com] Sent: Thursday, June 14, 2018 9:08 AM To: Robert Lewis Cc: nysbirds-l Subject: Re: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island Bob, Molt, (and I am including change in soft part colors such as bill and leg color under the term “molt”) is hormonally controlled. There is also considerable variation between individuals in the timing of molt. The timing and sequence of molt is no where as neat and fixed as many references might lead you to believe. Having worked extensively with a banded population, where the age of individuals is known from their banding histories, I know how much variation there is. I have seen birds with extensive white foreheads (or heavy speckling) and extensive carpal bars that I knew from their bands were two years old. I have also seen two year olds that were indistinguishable from normal adults. I have also seen that I knew were three, or four years old (or older based on their bands) that showed speckled foreheads and traces of carpal bars. I have se
Re: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island
For anyone interested in simply seeing a bird of this type, there is currently one on the beach at Nickerson. Also present are at least 4 Roseate Terns, and many young Common Terns. > On Jun 14, 2018, at 20:51, Joseph DiCostanzo wrote: > > I just wanted to add some information to my comments about variation in > individuals. I looked at data from Common Terns trapped on Great Gull Island > in the summer of 2017. We have weights on 918 individuals. The weights ranged > from 99.1 grams to 158.9 grams. That means at the extremes, the largest birds > were 60% more massive than the smallest birds. That kind of difference is > likely to be noticeable in the field. And that difference is not between > different subspecies or populations, but within a single colony. > > I should point out that these 918 birds were nearly all trapped on nests, so > they are healthy birds. Also the birds at the top and bottom of that range > were not extreme outliers. At both extremes, there were numbers of > individuals within 10 grams of those lowest and highest weights. For the > statistically minded, the average weight was 126.0 grams and the standard > deviation was 9.45. > > Joe DiCostanzo > > Sent from my iPad > > -- > > NYSbirds-L List Info: > http://www.NortheastBirding.com/NYSbirdsWELCOME.htm > http://www.NortheastBirding.com/NYSbirdsRULES.htm > http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm > > ARCHIVES: > 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html > 2) http://www.surfbirds.com/birdingmail/Group/NYSBirds-L > 3) http://birding.aba.org/maillist/NY01 > > Please submit your observations to eBird: > http://ebird.org/content/ebird/ > > -- > -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME.htm http://www.NortheastBirding.com/NYSbirdsRULES.htm http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/NYSBirds-L 3) http://birding.aba.org/maillist/NY01 Please submit your observations to eBird: http://ebird.org/content/ebird/ --
Re: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island
I just wanted to add some information to my comments about variation in individuals. I looked at data from Common Terns trapped on Great Gull Island in the summer of 2017. We have weights on 918 individuals. The weights ranged from 99.1 grams to 158.9 grams. That means at the extremes, the largest birds were 60% more massive than the smallest birds. That kind of difference is likely to be noticeable in the field. And that difference is not between different subspecies or populations, but within a single colony. I should point out that these 918 birds were nearly all trapped on nests, so they are healthy birds. Also the birds at the top and bottom of that range were not extreme outliers. At both extremes, there were numbers of individuals within 10 grams of those lowest and highest weights. For the statistically minded, the average weight was 126.0 grams and the standard deviation was 9.45. Joe DiCostanzo Sent from my iPad -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME.htm http://www.NortheastBirding.com/NYSbirdsRULES.htm http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/NYSBirds-L 3) http://birding.aba.org/maillist/NY01 Please submit your observations to eBird: http://ebird.org/content/ebird/ --
RE: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island
Shai and Joe, Great job by both of you. I learned a great deal from this discussion! If only I possessed the visual acuity to actually discern these details... Bob Grover d +1 (631) 761-7369 | c +1 (516) 318-8536 -Original Message- From: bounce-122638150-3714...@list.cornell.edu On Behalf Of Joseph DiCostanzo Sent: Thursday, June 14, 2018 11:35 AM To: Shaibal Mitra Cc: NYSBIRDS (NYSBIRDS-L@cornell.edu) Subject: Re: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island Shai, I certainly did not intend to “categorically dismiss” any line of evidence. And I certainly did not mean to say longipennis is an impossibility (see my last post to Bob). I think we completely agree that there is a tendency to not think “quantitatively” - no where enough consideration is given to variability in common species. So when an individual does not fit the “field guide” picture of the common species there is often a tendency to immediately go for something rare instead of giving enough consideration to variation in the more likely occurring species. Of course rarities do occur! Birding wouldn’t be nearly as much fun as it is without them. The operative word, however, is “rare”. As the saying goes in medial diagnostics, “If you hear hoofbeats in the distance, think horse, not zebra.” (Unless, of course, you are in Africa. :) ) Joe Sent from my iPad > On Jun 14, 2018, at 10:49 AM, Shaibal Mitra > wrote: > > As I mentioned in my earlier note to the list on this subject (8 Jun 18, > copied at the very end of the present note), the jury is certainly still out > on the status of longipennis Common Terns on the east coast. Joe's highly > informed contributions are a very welcome addition to the process and > underscore several areas to focus on in resolving the matter. First, it is > clearly true that to claim an extralimital longipennis, the evidence must be > very strong and include multiple characters beyond dark bills and dark legs. > I have a lot to contribute on this front, because I have made a point of > studying non-breeding terns for more than 20 years, during which time I have > collected detailed data on large samples of carefully scored first-summers > and "second-summer types" (a category which, as Joe notes, consists of an odd > amalgam of a subset of some but not all two year-olds, older adults short of > full breeding condition, and very old, senescent adults)--not only of Common > Terns, but also of Arctic, Roseate, Least, Black, and others. > > For now I just want to make two very simple points in response to the queries > Joe raises toward the end of his note. > > First, I'd like to address Joe's skepticism about judging wing length > visually. I once wrote a long, detailed note to the ID Frontiers list > defending the critical, visual assessment of shape (i.e., the relative sizes > of morphological structures; that piece concerned warblers, or maybe willets, > or maybe I did it separately for both?). I might be able to dig it/them up, > but for now I remember demonstrating that large samples of in-hand > measurements counter-intuitively often obscure real differences between > similar species, males and females, etc. The reason is that handbooks > over-emphasize extreme data, neglecting quantitative measures of variance and > covariance, and because most observers are unprepared or unwilling to think > quantitatively. At the same time, sharp-eyed birders can unerringly > distinguish Blackpoll and Pine Warblers at a glance by shape, even though > practically all their measurements, viewed individually in huge samples, > overlap. With regard to terns, I can recognize visually how the length of an > individual's primary projection compares to the chord of its dorsum with > enough precision to distinguish Common and Arctic Terns very confidently. So > I would caution against categorically dismissing this line of evidence. > > Second, the true statuses of non-breeding seabirds remain an amazing mystery, > and the few glimpses we've had so far have been really exciting. Most > obviously, the local status of Arctic Tern has been completely re-written in > the past 20 years based precisely on attention to loafing flocks of > non-breeding terns. Furthermore, scrutiny of these flocks has yielded many > other rarities, some of them as unexpected as longipennis might seem: Elegant > Tern, Cayenne Tern, acuflavidus Sandwich Terns during June, Little Gulls > during June, etc. My point is that although the improbability of longipennis > needs to be answered with strong evidence, much stranger things have > happened. I still examine every Arctic Tern I see with the remote potential > of Antarctic Tern in mind; the non-breeders hang out together down there, so
Re: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island
Shai, I certainly did not intend to “categorically dismiss” any line of evidence. And I certainly did not mean to say longipennis is an impossibility (see my last post to Bob). I think we completely agree that there is a tendency to not think “quantitatively” - no where enough consideration is given to variability in common species. So when an individual does not fit the “field guide” picture of the common species there is often a tendency to immediately go for something rare instead of giving enough consideration to variation in the more likely occurring species. Of course rarities do occur! Birding wouldn’t be nearly as much fun as it is without them. The operative word, however, is “rare”. As the saying goes in medial diagnostics, “If you hear hoofbeats in the distance, think horse, not zebra.” (Unless, of course, you are in Africa. :) ) Joe Sent from my iPad > On Jun 14, 2018, at 10:49 AM, Shaibal Mitra > wrote: > > As I mentioned in my earlier note to the list on this subject (8 Jun 18, > copied at the very end of the present note), the jury is certainly still out > on the status of longipennis Common Terns on the east coast. Joe's highly > informed contributions are a very welcome addition to the process and > underscore several areas to focus on in resolving the matter. First, it is > clearly true that to claim an extralimital longipennis, the evidence must be > very strong and include multiple characters beyond dark bills and dark legs. > I have a lot to contribute on this front, because I have made a point of > studying non-breeding terns for more than 20 years, during which time I have > collected detailed data on large samples of carefully scored first-summers > and "second-summer types" (a category which, as Joe notes, consists of an odd > amalgam of a subset of some but not all two year-olds, older adults short of > full breeding condition, and very old, senescent adults)--not only of Common > Terns, but also of Arctic, Roseate, Least, Black, and others. > > For now I just want to make two very simple points in response to the queries > Joe raises toward the end of his note. > > First, I'd like to address Joe's skepticism about judging wing length > visually. I once wrote a long, detailed note to the ID Frontiers list > defending the critical, visual assessment of shape (i.e., the relative sizes > of morphological structures; that piece concerned warblers, or maybe willets, > or maybe I did it separately for both?). I might be able to dig it/them up, > but for now I remember demonstrating that large samples of in-hand > measurements counter-intuitively often obscure real differences between > similar species, males and females, etc. The reason is that handbooks > over-emphasize extreme data, neglecting quantitative measures of variance and > covariance, and because most observers are unprepared or unwilling to think > quantitatively. At the same time, sharp-eyed birders can unerringly > distinguish Blackpoll and Pine Warblers at a glance by shape, even though > practically all their measurements, viewed individually in huge samples, > overlap. With regard to terns, I can recognize visually how the length of an > individual's primary projection compares to the chord of its dorsum with > enough precision to distinguish Common and Arctic Terns very confidently. So > I would caution against categorically dismissing this line of evidence. > > Second, the true statuses of non-breeding seabirds remain an amazing mystery, > and the few glimpses we've had so far have been really exciting. Most > obviously, the local status of Arctic Tern has been completely re-written in > the past 20 years based precisely on attention to loafing flocks of > non-breeding terns. Furthermore, scrutiny of these flocks has yielded many > other rarities, some of them as unexpected as longipennis might seem: Elegant > Tern, Cayenne Tern, acuflavidus Sandwich Terns during June, Little Gulls > during June, etc. My point is that although the improbability of longipennis > needs to be answered with strong evidence, much stranger things have > happened. I still examine every Arctic Tern I see with the remote potential > of Antarctic Tern in mind; the non-breeders hang out together down there, so > maybe a few stick together up here, too. Ditto for examining first-summer > Least Terns for Littles and first-summer Black Terns for White-winged and > Whiskered. > > Brian Patteson recently saw a Tahiti Petrel off of Hatteras! > > Shai Mitra > Bay Shore > > > > From: bounce-122637763-11143...@list.cornell.edu > [bounce-122637763-11143...@list.cornell.edu] on behalf of Joseph DiCostanzo > [jdic...@ny
Re: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island
Bob, I am not saying a Siberian longipennis race Common Tern is a total impossibility here in the east. Among shorebirds, many of us saw the Broad-billed Sandpiper at Jamaica Bay years ago and there are multiple records of Sharp-tailed Sandpipers in the northeast. I am saying that an aberrant hirundo would fit the bill just as well and seems much more likely. At least the Gray-hooded Gull is from this (Western) hemisphere and it does occur together with wintering Laughing Gulls on the north coast of South America. You just don’t have that same possibility for a longipennis to take up with a northbound flock of hirundo. Joe Sent from my iPad > On Jun 14, 2018, at 10:44 AM, Robert Lewis wrote: > > Thanks for the thorough reply. As a long time student of gulls, I am aware > of the concepts you delineated about timing and odd individuals that don't > fit the norms. > > As for how did it (they) get here, stranger things have happened, namely the > Gray-hooded gull of a few years back. Ship-assisted? Who knows. > > Bob Lewis > > On Thursday, June 14, 2018, 9:08:12 AM EDT, Joseph DiCostanzo > wrote: > > > Bob, > > Molt, (and I am including change in soft part colors such as bill and leg > color under the term “molt”) is hormonally controlled. There is also > considerable variation between individuals in the timing of molt. The timing > and sequence of molt is no where as neat and fixed as many references might > lead you to believe. Having worked extensively with a banded population, > where the age of individuals is known from their banding histories, I know > how much variation there is. I have seen birds with extensive white foreheads > (or heavy speckling) and extensive carpal bars that I knew from their bands > were two years old. I have also seen two year olds that were > indistinguishable from normal adults. I have also seen that I knew were > three, or four years old (or older based on their bands) that showed speckled > foreheads and traces of carpal bars. I have seen adults in August at the > breeding colony on Great Gull Island that were already in full winter plumage > (black bill, dark legs, carpal bar). Individuals that don’t match the > expected are unusual, but they do occur. > > As for the lack of a carpal bar on these dark billed, dark legged > individuals, you are assuming that feather molt (carpal bar) and soft part > colors (legs and bill) must be in total lock-step with each other. There is > no reason they couldn’t be out of sync in some instances. As for primary > length, this is being based on photos, not actual measurements of the bird in > hand. How is the primary length being assessed? I am guessing versus tail > length. How does anyone know the tail length? > > These dark billed, dark legged Common Terns get reported every year at this > season, just at the time young Common Terns are coming back from South > America. Where are these supposed longipennis birds coming from? The race > breeds in Siberia and winters in the Indian Ocean east to Australia. If > longipennis were going to occur here on the East Coast, the fall seems a more > likely time than the spring migration. It seems far more likely that these > birds are aberrant hirundo retaining aspects of their winter/non-breeding > plumage than that there is an annual movement of Siberian based longipennis > birds through Long Island. > > Joe DiCostanzo > > Sent from my iPad > >> On Jun 14, 2018, at 7:59 AM, Robert Lewis wrote: >> >> Good points Joe. >> >> Let's go with the null hypothesis: it's an unusual Common tern (hirundo). >> Apparently a Common tern in September can get gray blotches on the >> underparts. During the winter they have a black bill, black legs, and a >> black cap with white forehead, as first summer birds do now. If it is four - >> eight months late in molt (or four months early), maybe that would explain >> some features. But then there should be a prominent dark carpal bar. >> Instead, there is none. Also, how to explain the very long primaries? And >> the fact that the back is a bit darker gray than neighboring Commons, both >> adult and immature? >> >> I found a number of images of longipennis on the web. Here are some screen >> shots: >> >> Index of /lewis/birds/other_long >> >> Index of /lewis/birds/other_long >> >> Bob Lewis >> >> >> >> On Wednesday, June 13, 2018, 9:01:37 PM EDT, Joseph DiCostanzo >> wrote: >> >> >> One thing that has to be kept in mind about dark billed and/or dark legged >> Common Terns seen on Long Island in the spring is that our Common Terns >> (Sterna hirundo hirundo) have dark bills and dark legs in winter (both the >> young birds and adults). The possibility that these birds are just S. >> hirundo hirundo retaining aspects of their winter plumage must be >> considered. Indeed, given the breeding and wintering ranges of S. hirundo >> longipennis, S. hirundo hirundo with retained winter c
RE: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island
As I mentioned in my earlier note to the list on this subject (8 Jun 18, copied at the very end of the present note), the jury is certainly still out on the status of longipennis Common Terns on the east coast. Joe's highly informed contributions are a very welcome addition to the process and underscore several areas to focus on in resolving the matter. First, it is clearly true that to claim an extralimital longipennis, the evidence must be very strong and include multiple characters beyond dark bills and dark legs. I have a lot to contribute on this front, because I have made a point of studying non-breeding terns for more than 20 years, during which time I have collected detailed data on large samples of carefully scored first-summers and "second-summer types" (a category which, as Joe notes, consists of an odd amalgam of a subset of some but not all two year-olds, older adults short of full breeding condition, and very old, senescent adults)--not only of Common Terns, but also of Arctic, Roseate, Least, Black, and others. For now I just want to make two very simple points in response to the queries Joe raises toward the end of his note. First, I'd like to address Joe's skepticism about judging wing length visually. I once wrote a long, detailed note to the ID Frontiers list defending the critical, visual assessment of shape (i.e., the relative sizes of morphological structures; that piece concerned warblers, or maybe willets, or maybe I did it separately for both?). I might be able to dig it/them up, but for now I remember demonstrating that large samples of in-hand measurements counter-intuitively often obscure real differences between similar species, males and females, etc. The reason is that handbooks over-emphasize extreme data, neglecting quantitative measures of variance and covariance, and because most observers are unprepared or unwilling to think quantitatively. At the same time, sharp-eyed birders can unerringly distinguish Blackpoll and Pine Warblers at a glance by shape, even though practically all their measurements, viewed individually in huge samples, overlap. With regard to terns, I can recognize visually how the length of an individual's primary projection compares to the chord of its dorsum with enough precision to distinguish Common and Arctic Terns very confidently. So I would caution against categorically dismissing this line of evidence. Second, the true statuses of non-breeding seabirds remain an amazing mystery, and the few glimpses we've had so far have been really exciting. Most obviously, the local status of Arctic Tern has been completely re-written in the past 20 years based precisely on attention to loafing flocks of non-breeding terns. Furthermore, scrutiny of these flocks has yielded many other rarities, some of them as unexpected as longipennis might seem: Elegant Tern, Cayenne Tern, acuflavidus Sandwich Terns during June, Little Gulls during June, etc. My point is that although the improbability of longipennis needs to be answered with strong evidence, much stranger things have happened. I still examine every Arctic Tern I see with the remote potential of Antarctic Tern in mind; the non-breeders hang out together down there, so maybe a few stick together up here, too. Ditto for examining first-summer Least Terns for Littles and first-summer Black Terns for White-winged and Whiskered. Brian Patteson recently saw a Tahiti Petrel off of Hatteras! Shai Mitra Bay Shore From: bounce-122637763-11143...@list.cornell.edu [bounce-122637763-11143...@list.cornell.edu] on behalf of Joseph DiCostanzo [jdic...@nyc.rr.com] Sent: Thursday, June 14, 2018 9:08 AM To: Robert Lewis Cc: nysbirds-l Subject: Re: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island Bob, Molt, (and I am including change in soft part colors such as bill and leg color under the term “molt”) is hormonally controlled. There is also considerable variation between individuals in the timing of molt. The timing and sequence of molt is no where as neat and fixed as many references might lead you to believe. Having worked extensively with a banded population, where the age of individuals is known from their banding histories, I know how much variation there is. I have seen birds with extensive white foreheads (or heavy speckling) and extensive carpal bars that I knew from their bands were two years old. I have also seen two year olds that were indistinguishable from normal adults. I have also seen that I knew were three, or four years old (or older based on their bands) that showed speckled foreheads and traces of carpal bars. I have seen adults in August at the breeding colony on Great Gull Island that were already in full winter plumage (black bill, dark legs, carpal bar). Individuals that don’t match the expected are unusual, but they do occur. As for the lack o
Re: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island
Thanks for the thorough reply. As a long time student of gulls, I am aware of the concepts you delineated about timing and odd individuals that don't fit the norms. As for how did it (they) get here, stranger things have happened, namely the Gray-hooded gull of a few years back. Ship-assisted? Who knows. Bob Lewis On Thursday, June 14, 2018, 9:08:12 AM EDT, Joseph DiCostanzo wrote: Bob, Molt, (and I am including change in soft part colors such as bill and leg color under the term “molt”) is hormonally controlled. There is also considerable variation between individuals in the timing of molt. The timing and sequence of molt is no where as neat and fixed as many references might lead you to believe. Having worked extensively with a banded population, where the age of individuals is known from their banding histories, I know how much variation there is. I have seen birds with extensive white foreheads (or heavy speckling) and extensive carpal bars that I knew from their bands were two years old. I have also seen two year olds that were indistinguishable from normal adults. I have also seen that I knew were three, or four years old (or older based on their bands) that showed speckled foreheads and traces of carpal bars. I have seen adults in August at the breeding colony on Great Gull Island that were already in full winter plumage (black bill, dark legs, carpal bar). Individuals that don’t match the expected are unusual, but they do occur. As for the lack of a carpal bar on these dark billed, dark legged individuals, you are assuming that feather molt (carpal bar) and soft part colors (legs and bill) must be in total lock-step with each other. There is no reason they couldn’t be out of sync in some instances. As for primary length, this is being based on photos, not actual measurements of the bird in hand. How is the primary length being assessed? I am guessing versus tail length. How does anyone know the tail length? These dark billed, dark legged Common Terns get reported every year at this season, just at the time young Common Terns are coming back from South America. Where are these supposed longipennis birds coming from? The race breeds in Siberia and winters in the Indian Ocean east to Australia. If longipennis were going to occur here on the East Coast, the fall seems a more likely time than the spring migration. It seems far more likely that these birds are aberrant hirundo retaining aspects of their winter/non-breeding plumage than that there is an annual movement of Siberian based longipennis birds through Long Island. Joe DiCostanzo Sent from my iPad On Jun 14, 2018, at 7:59 AM, Robert Lewis wrote: Good points Joe. Let's go with the null hypothesis: it's an unusual Common tern (hirundo). Apparently a Common tern in September can get gray blotches on the underparts. During the winter they have a black bill, black legs, and a black cap with white forehead, as first summer birds do now. If it is four - eight months late in molt (or four months early), maybe that would explain some features. But then there should be a prominent dark carpal bar. Instead, there is none. Also, how to explain the very long primaries? And the fact that the back is a bit darker gray than neighboring Commons, both adult and immature? I found a number of images of longipennis on the web. Here are some screen shots: Index of /lewis/birds/other_long | | | | Index of /lewis/birds/other_long | | | Bob Lewis On Wednesday, June 13, 2018, 9:01:37 PM EDT, Joseph DiCostanzo wrote: One thing that has to be kept in mind about dark billed and/or dark legged Common Terns seen on Long Island in the spring is that our Common Terns (Sterna hirundo hirundo) have dark bills and dark legs in winter (both the young birds and adults). The possibility that these birds are just S. hirundo hirundo retaining aspects of their winter plumage must be considered. Indeed, given the breeding and wintering ranges of S. hirundo longipennis, S. hirundo hirundo with retained winter characters seems a more likely possibility. Joe DiCostanzo Sent from my iPad -- -- -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME.htm http://www.NortheastBirding.com/NYSbirdsRULES.htm http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/NYSBirds-L 3) http://birding.aba.org/maillist/NY01 Please submit your observations to eBird: http://ebird.org/content/ebird/ --
Re: [nysbirds-l] Dark billed, dark legged Common Terns on Long Island
Bob, Molt, (and I am including change in soft part colors such as bill and leg color under the term “molt”) is hormonally controlled. There is also considerable variation between individuals in the timing of molt. The timing and sequence of molt is no where as neat and fixed as many references might lead you to believe. Having worked extensively with a banded population, where the age of individuals is known from their banding histories, I know how much variation there is. I have seen birds with extensive white foreheads (or heavy speckling) and extensive carpal bars that I knew from their bands were two years old. I have also seen two year olds that were indistinguishable from normal adults. I have also seen that I knew were three, or four years old (or older based on their bands) that showed speckled foreheads and traces of carpal bars. I have seen adults in August at the breeding colony on Great Gull Island that were already in full winter plumage (black bill, dark legs, carpal bar). Individuals that don’t match the expected are unusual, but they do occur. As for the lack of a carpal bar on these dark billed, dark legged individuals, you are assuming that feather molt (carpal bar) and soft part colors (legs and bill) must be in total lock-step with each other. There is no reason they couldn’t be out of sync in some instances. As for primary length, this is being based on photos, not actual measurements of the bird in hand. How is the primary length being assessed? I am guessing versus tail length. How does anyone know the tail length? These dark billed, dark legged Common Terns get reported every year at this season, just at the time young Common Terns are coming back from South America. Where are these supposed longipennis birds coming from? The race breeds in Siberia and winters in the Indian Ocean east to Australia. If longipennis were going to occur here on the East Coast, the fall seems a more likely time than the spring migration. It seems far more likely that these birds are aberrant hirundo retaining aspects of their winter/non-breeding plumage than that there is an annual movement of Siberian based longipennis birds through Long Island. Joe DiCostanzo Sent from my iPad > On Jun 14, 2018, at 7:59 AM, Robert Lewis wrote: > > Good points Joe. > > Let's go with the null hypothesis: it's an unusual Common tern (hirundo). > Apparently a Common tern in September can get gray blotches on the > underparts. During the winter they have a black bill, black legs, and a black > cap with white forehead, as first summer birds do now. If it is four - eight > months late in molt (or four months early), maybe that would explain some > features. But then there should be a prominent dark carpal bar. Instead, > there is none. Also, how to explain the very long primaries? And the fact > that the back is a bit darker gray than neighboring Commons, both adult and > immature? > > I found a number of images of longipennis on the web. Here are some screen > shots: > > Index of /lewis/birds/other_long > > Index of /lewis/birds/other_long > > Bob Lewis > > > > On Wednesday, June 13, 2018, 9:01:37 PM EDT, Joseph DiCostanzo > wrote: > > > One thing that has to be kept in mind about dark billed and/or dark legged > Common Terns seen on Long Island in the spring is that our Common Terns > (Sterna hirundo hirundo) have dark bills and dark legs in winter (both the > young birds and adults). The possibility that these birds are just S. hirundo > hirundo retaining aspects of their winter plumage must be considered. Indeed, > given the breeding and wintering ranges of S. hirundo longipennis, S. hirundo > hirundo with retained winter characters seems a more likely possibility. > > Joe DiCostanzo > > Sent from my iPad > > -- > > -- -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME.htm http://www.NortheastBirding.com/NYSbirdsRULES.htm http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/NYSBirds-L 3) http://birding.aba.org/maillist/NY01 Please submit your observations to eBird: http://ebird.org/content/ebird/ --
[nysbirds-l] Dark billed, dark legged Common Terns on Long Island
One thing that has to be kept in mind about dark billed and/or dark legged Common Terns seen on Long Island in the spring is that our Common Terns (Sterna hirundo hirundo) have dark bills and dark legs in winter (both the young birds and adults). The possibility that these birds are just S. hirundo hirundo retaining aspects of their winter plumage must be considered. Indeed, given the breeding and wintering ranges of S. hirundo longipennis, S. hirundo hirundo with retained winter characters seems a more likely possibility. Joe DiCostanzo Sent from my iPad -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME.htm http://www.NortheastBirding.com/NYSbirdsRULES.htm http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/NYSBirds-L 3) http://birding.aba.org/maillist/NY01 Please submit your observations to eBird: http://ebird.org/content/ebird/ --
