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There's long been a bit of a dichotomy in American birdwatching (despite substantial overlap) between what I'll call the 'pure birders' or 'top-notch birders' and the 'ornithologists.' By top-notch birders I mean not just 'rock stars' like Sibley, Dunne, Kaufman, but also, those who may be lesser known to the public, but are huge in the birding world for their accomplishments/abilities, if not for their writings. These are excellent, experienced birders, highly knowledgeable as well as instinctive; they'll make a living out of birding if they can figure out a way to turn their recreational love into a vocation. The ornithologists, on-the-other-hand, are birders as well of course, but more academic in focus, with specialized interests and pursuits, and a lot of 'book-learning,' with the act of birding more of a side-endeavor. The two sides certainly overlap greatly, yet their focuses tend to differ. Pure birders may be more attentive to 'life-lists,' identification, hotspots, field gear, and the like. 'Ornithologists' take a more scientific and academic interest in birds, including bird behavior and conservation/habitat issues as well.
Any readers who are members of the American Birding Association (ABA) know that it is going through a transition right now and trying to determine just what it's focus will be in the future --- again, it is largely a debate between those who want a recreational/hobbyist focus on pure birding, and those who definitely want the organization involved in conservation/political/scientific issues that relate to birds. It is interesting to watch it play out.
I mention all of this because one of the most fascinating aspects of the IBWO debate over these years has indeed been the 'birder' vs. 'ornithologist' debate in the form of David Sibley vs. Cornell (over the Luneau video). In point of fact, David has a large slew of 'ornithologists' or academics who side with him on this issue, believing the Luneau bird to be a Pileated (and for that matter a significant number of 'birders' side with the Cornell ornithologists in their interpretation of the video as an IBWO).
With the exception of Roger Tory Peterson (and maybe Audubon himself), America has rarely had a birding figure as esteemed, experienced, respected, renowned, multi-talented and iconic as David Sibley. Thus when he speaks (even if he didn't have the backing of others) the birding community stands at attention. If David had said the Luneau bird was an Ivory-bill, I suspect the doubts of Jackson, Prum, Bevier, Collinson, and so many others, would've largely been muted in the birding community; such is his influence. But of course, David said otherwise, and the entire weight of the debate turned.
Yet David's position (though not that of all the critics) relies on his assertion of "wing-twisting" in the downbeat of a Pileated Woodpecker's flap (a motion that Cornell claims cannot be detected on any comparable available videos of Pileateds in flight). It's odd to me that David's idea of wing-twisting flaps hasn't been definitively proven or disproven by now... we have quite precise knowledge of the movement-pattern for the wings of a hummingbird flashing at 50 beats/sec. --- can't we determine to everyone's agreement the precise movement-pattern for the wings of a cruising (lumbering, by comparison) Pileated Woodpecker (to what degree for example, did Jeffrey Wang's animated analysis of a Pileated-in-flight, exhibit twisting wings)??? While the Luneau video is fuzzy and blurry and brief, can modern day technology not decipher where the white shown is coming from? That, by itself, wouldn't end this debate (and the claim for the existence of IBWOs rests on a LOT more than the Luneau clip), but at least this one narrow argument might attain some conclusion.
There is NO POINT in having those who have already taken a public stance on the IBWO, further analyzing the Luneau clip and re-stating their cases, but I do wonder if somewhere out there, there isn't a group of excellent, experienced, detached wildlife videographers (with the Smithsonian, National Geographic, the BBC, or any number of other possibilities), who have not taken a stand, and who would be viewed as objective and supremely competent to pass judgment on what is seen in this video (and on PIWO videos) --- a group, BTW, that requires little expertise in birding, but keen, seasoned expertise in film-making and analysis.
....and I say all this as someone who thinks we've already spent waaaaaay too much time on a single silly 4-second clip of accidental video!
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24 comments:
I personally do not believe that Mr. Sibley's wing-twisting can be linked to the case of Mr. Luneau's video as a result of the extensive white on the wings shown throughout the entirety of the video. I would agree with Mr. Sibley if in-fact extensive amount of white only displayed itself in take-off. This would lead to the conclusion that the bird was a Pileated Woodpecker. But Pileated Woodpecker wings are not designed to twist through a get-away flight at high speeds and keep a wing-beat frequency as that of an Ivory-bill. I am surprised that other prominent ornithologists who have sided with Sibley, and Sibley himself, have not realised that. Just my thoughts on the matter.
I would like to think that the great majority of birders with anything like a degree of competence would not even try to identify a bird from such fuzzy video. Once you try to do so, you're out of the game for me. You end up interpreting things, putting your own take on what might or might not be 'real' in the images etc
I would much have preferred to see people say "If it was an IBWO, lets get back there now and find it, and record it properly." It never happened.
Sibley et al only got involved when people started claiming from very poor video that the bird was an IBWO. Sibley and Co. thought they were doing the right thing but I think they should have left well alone and let history take its course. As it has done. People who wish to believe it was an IBWO, still can, and people who believe it wasn't can point to subsequent events and lack of documented birds and ultimately a loss of interest from Cornell. No harm done as long as we aren't counting dollars 'wasted'
No one is competent enough to properly pass judgement on the video. You're asking the wrong question, and this too, has been borne out by history.
You may ultimately be right Spat, and my point is that we needn't hear from more birders (attempting field bird identification) in this instance, but from video techies who maybe can shed more light on film artifacts/angles/exposure etc. (IF anything at all can be concluded from so few pixels).
The other point is that Sibley (unlike other critics) makes a VERY SPECIFIC claim about wing-motion (such that he thinks we are viewing the wing underside on downbeat when many think they are viewing the wing dorsal side -- I'm not sure if he concludes this from personal observation or from anatomical study of PIWOs?), and THAT motion ought to be physically verifiable... or refutable! (although the EXACT degree of 'wing-twisting' and precise angle of the Luneau bird may still be open to controversy :-( ) ughhh...
I wouldn't say that we should necessarily be out of the game so to speak. At least not for the Ivory-bill. So far all that has been collected is fuzzy videos and fuzzy photos that push our identification ability to the limits. I believe that if the circumstances were different, as in if the bird wasn't so hard to find already then yes perhaps we shouldn't have opinions from all the experts and non-experts to believe that the bird is what they perceive. through the fuzzy evidence. The bird itself is nomadic and very wary decreasing our chances of getting the perfect photo.
They basically did. More in a roundabout way I would say, and perhaps it was as a result of Sibley getting involved. They went back in there and tried to find the bird. The searches were not successful in obtaining the 'perfect ' photo but they did get sightings and recordings that can just about conclusively say the bird's presence is there.
I can agree with you there. Sibley and his counterparts should have left the whole thing alone. I reckon now that it is the past it should be left alone, what is done is done.
Cyberthrush, I might agree with Sibley's wing-twisting if there is some hard evidence suggesting so. I have never seen a Pileated show that much white on its wings in a 'retreat' flight. I don't think that a Pileated Woodpecker's wings are made to be able to twist to show that much white, especially in a flight to get out of the area as fast as possible. Perhaps if their wings were long and thin or built anatomically different so that they could do so to maximize their flight speed. Also a Pileated's white on the underside is limited to mostly the primaries. If the bird was wing-twisting then wouldn't the viewer have seen some extent of black from the secondaries in the wings. If the bird was wing-twisting is it not likely that the secondaries would have been pointed upwards and the viewer to have seen them? Instead the viewer sees long narrow wings showing practically only white, characteristic of an Ivory-bill. As a result that video was fuzzy perhaps the thin black line in the underside of the wing (visible during the upstroke) would have been blurred out by the extensive amount of white.
Just my opinion
I don't know where we are going to find a monastery of disinterested ornithologists with video analysis skills to provide a detached consensus view. Personally, I think Bill Pulliam set the standard. As for David Sibley, I don't think data will make a difference because he says on his blog, "I drove home thinking 'If this bird still exists, somebody will find it within a month' because there was so much excitement and every acre of that swamp was hunted or fished at some point." He starts with the assumption that if the bird is there, someone will get a good photo of it and molds the data to fit his hypothesis.
I'm not looking for "disinterested ornithologists' but for previously uninvolved filmographers (with little ornithology experience).
...as far as 'molding the data to fit one's hypothesis,' that is a charge that gets frequently tossed at both sides.
My question for you cyberthrush is, what would the video analysts determine? If they have little to know experience with birds, let alone Ivory-billed Woodpeckers, chances are they wouldn't be able to tell us much. The whole point of the video debate is really about whether or not the Luneau video is of an Ivory-bill or not. I admit it would be interesting to hear what they say, but I don't have much hope that they would shed new light on the video.
It is difficult to find an Ivory-bill let alone capture a 'worthy' photograph. So in my opinion, for Sibley to give one months time is quite unrealistic, especially since it has been several years and so far only inconclusive videos and photos. I really think Mr. Sibley should take two months or more and go out in a swamp, where Ivory-bills have been recently seen, and stay there searching for the Ivory-bill until the time period is up, just so he can know how hard it really is to find and photograph and find the birds. From his post I get the vibe that he believes this whole deal is a chipshot, when it clearly is not.
Hi Jacob, I don't want to belabor the subject too much, but the point is that much disagreement around the Luneau clip is over how much of the visible white is coming from a flying creature and how much is just artifact or bleed -- birders are fine at seeing birds live in the field... I think professional filmmakers may be better at analyzing just such technical aspects of film.
If we ever know precisely which white is part of the bird and which is not, then the 2nd question is what part of the bird is it coming from (dorsal or ventral side).
And again, Spat may be right, that none of this will ever be knowable (to everyone's agreement). BUT I still contend the motion/pattern of a Pileated's wing-flap ought to be knowable!
Cyberthrush,
I never thought about bleed in the colours; now that you mention it it could be a possibility, which would cause need for video analysts. I do believe now that Sibley's idea of wing-twisting is more valid, but I still believe that in this case it seems too likely that the bird's wing is not showing the ventral side except when in the upstroke. Of course it all comes down to perspective.
Cyberthrush,
I chose to post on this site because it seems most up-to-date. I have just spent two exhaustive days obsessing on the Web as much as I could read about the IBWO and efforts to find it. I believe I am up to speed so to speak-- from Indian accounts to Rainsong. The reason for the obsession? No, I haven't seen one. My son and I just returned from a 20 day trip from New York to the upper Florida Keys, birding all the way, and I was able to get him 30 new spp. The closest we got to IB habitat, as far as I know, was a boardwalk to the Lower Suwanee River at Manatee Springs State Park. Anyway...
The reason for the obsession is, as a person with a science background, and a high school science teacher with the rest of the summer "off," I was hoping to prove to myself (and my interested son) its existence-or-not. Along the way, I also began having "was this tried?" "could this have worked?" kind of thinking. And, to my surprise, I spoke with Michael Collins personally just today and offered him a couple of thoughts that hopefully can help.
This "help" is why I post here. I take the liberty of not offering referencing, but anyone concerned and in a position to find these birds can reference easily from the Web, as I did. This is what I think about some of the controversies written about.
1. The IB is wary. This is in the literature almost 100 years ago. I'm reminded that, although Black Rails exist and have a known habitat, I (who does not sign up for focused bird expeditions) will most likely never see one. The IB seems to have a natural distance of roughly 100 meters. Exceptions in the last century-- reasons people give that the bird should be easier to see-- seem to be when it is nesting, or at least in that season.
2. It can exist for long times in small populations. Clues for this in the animal kingdom are mating for life, size of animal in comparison with others in habitat, lack of obvious predators, and longevity-- I feel that estimates of the lifespans of IBs are low, and that they might live 30+ years like some owls. More tropical Campephilus would have shorter lifespans. So these birds could exist in small numbers and maintain genetic diversity. Another clue to this is the number of spp. in the New World of Campephilus-- this does not have to necessarily be. The birds are somewhat segregatory, and thus have speciated, and we might be seeing a microcosm of this with the IB. Thus, they could survive a fragmented habitat.
Continued on next post because of max words allowed--
...continued
3. They use rivers as corridors, or possibly fly just over the canopy. Their wings are not built to maneuver through trees-- this is a rather basic fact in birding.
Perhaps some sort of remote control electric plane (painted red,black, white?) could be programmed to follow river corridors and take photos of motional objects.
4. They have short seasonal migration patterns, as Pileateds do, from more upland in Summer (I guess with Pines involved-- their numbers declined in the 1880s with pine logging)) to bottomland in Winter. I would go so far as to guess one could take existing accounts of IB sightings, use maps to determine the best upland woods as a transect, and have summer searches for them there. This leads to
5. I believe it is possible to use some form of "calling them in" to enhance the chances of a good photo record. Birds are somewhat predictable in their response to sounds, and there are some intriguing new sound recordings at ProjectCoyote. This was part of my idea offered to Mr. Collins-- instead of playing kents or double knocks at volume, try more of the other sounds attibuted to IBs, but at much lower levels. As an amateur birder, I have tried the various sounds to attract birds, and like many have found that, at times, birds may leave the scene. I suggest low-volume, repeated calls of IB vocalizations, such that the bird may not even react consciously but just be attracted to an area. And from what I've read, these sounds may not be the kent or double knock that will be attractive. Certainly it wound be worth it, and easy enough, to design a system to test this. A 10 db sound may work better than a 60 db of the same call. Leave it on for a whole week.
Another avenue for this acoustic attraction is the observation that woodpeckers seem to be able to detect their beetle larvae prey remotely on the tree-- presumably by hearing them. Modern science could quantify these vibrations. Perhaps amplified, they would prove irresistable to an IB miles away.
6. I presume that searchers know that birds have much better eyesight than humans, and that what we think of as camo may be not to the bird (another reason for the acoustic attraction belief). It may be better to wear white and black-- no joke!
I believe the IB persists. I think Sibley cannot explain the white to the left of the tree trunk in the Cornell video (a bird does not spread its wings to then turn around and fly-- it will launch first), and I have not read of any good critique for other videos and still images I saw on various websites.
Thanks,
John D. Williams
Hi John, thanks for taking the time to write and spell out your thoughts here... and, welcome to the world of obsession!! ;-)
In fact one of your ideas is intriguing enough to me that I'm going to use it for a separate post above to give it a wider audience, as well as draw attention to your other comments.
(1) I think there is considerable validity to the notion that more subdued sounds might work better to attract the birds. I strongly believe that Cornell's protocol of 7 simulated DK's over a period of a minute was a mistake. Because DK's work well with pale-billeds and Magellanics is no reason to think they will on ivory-bills. The former are strongly territorial birds.
(2) The idea of using beetle sounds to attract the birds has been discussed before. One problem is the apparent intermittent presence of the birds in a given area. But the bigger issue I think is simply one of technology and money. A mere automated sound recorder will cost upwards of $800. Or, if you wanted to get a Cornell ARU "on loan," I believe they wanted something like $1200 per 3 month deployment. Direction-finding would be nice to have, wouldn't it? Well, it's available now. Anyone can purchase groups of 3 sound recorders with time synchronization for direction finding. The price? About $4500/trio. A playback device - I wouldn't know where to start, but the financial outlay would undoubtedly be considerable. My point is that these things are quite feasible. But who is going to put up the funding?
Perhaps someday, programmable remote cameras, sound recorders, and playback devices will be as cheap as cell phones. But that day is not here.
Fangsheath, thanks for posting. I have read your great interest in IBs on a variety of sites. Allow me to clarify--
1. I wrote from a "money is no object" point of view, in a forum where I thought this might be read by an individual or group that could have the ways and means. Anyway, an individual such as Mike Collins or the ProjectCoyote, or anyone who wants to find the IB at last, could rig up something fairly low-cost to simply broadcast sounds to a likely area. I like to think this would not require a lot of volume, but would just use time, perhaps months, to bring an IB to a remote camera. You mention that they have intermittent presence, but what I offered is a way to attract them to an area, presuming there is some randomness when they decide to move in their foraging. The sounds would steer the randomness. This would either be with beetle sound frequencies, or some of the non-kent, non DK sounds attributed to the IB (ProjectCoyote again?).
2. On my property, I've been surprised more than once by the sudden close appearance of woodpeckers when I was wearing white, red, and black in some form. I know the camo works but it makes me wonder.
And as far as putting up the funding-- I wish I could! If what I write helps at all, it is from the perspective of a middle class, career natural scientist-environmental educator-writer-teacher-birder.
Thanks,
John
My apologies if I sound discouraging, these suggestions are certainly worthwhile. The technology is constantly improving and the funding will flow when the birds are clearly documented.
There are existing and tested methods that consistently locate IBWOs with a very acceptable and encouraging detection function of ~ 1 bird per ten square miles in specific but multiple locations.
There is also a very acceptable attraction rate. Unfortunately most teams attempted super stimuli which has never been proven or even tested on a heavily hunted population of Campephilus. The flaws in this aggressive and probably inappropriate method should have been noticed and adjusted years ago as negative data for that field set accumulated into a massive pile of 3,000 + points for at least one team. This was contrary to some of their very own data sets such as sightings, ambient sound detections, bark, roosts, etc.
"Mandibular beetle broadcasts" could be secondary to a more promising area we have discussed. The olfactory lobes of Picidae are relatively large among birds. Numerous references state or infer that ants, bees, beetles give off formic acid. Formic acid is a small molecule, favorable to having potentiality in the evolutionary development of prey detection senses of generalists and some specialists.
The competing method of beetle mandibular broadcasts, if surveying large areas per point, has a flaw. Mandibular sounds, if used as prey location stimuli by IBWOs are a short distance and secondary or tertiary signal. For anthropomorphic broadcasts, as the target approaches the source the high amplitude of the sound will no longer mimic natural conditions hundreds of yards away and would likely prove a deterrent rather than an attractant to the camera trap. In addition, if you could somehow match the acoustical frequencies of beetle larvae from a single point over long distances, when the amplitude indicates to an IBWO that beetles are within ten feet wouldn't the IBWO just search for the nearest standing dead wood? This would be hundreds of yards short of the camera trap.
Moving up a chemical gradient for an IBWO right to the sources seems a more natural occuring stimuli since a higher concentration just indicates a higher number of beetles more densely concetrated which is exacly what an IBWO is in search of.
Combining a close range attraction method (formic acid, beetle sounds) with a method that has a large and effective acoustical footprint (correctly designed and tested ADK survey methods) could eventually work.
However how does this all really help the IBWO in LA if you get a picture in TN? The habitat connectivity is being chipped away as we get involved with these multi-tiered, biased, decision processes that at this rate will fail.
It all plays into the slow game the committee and the skeptics have forced upon the recovery of this species and we are much to obliging.
The IBWO will benefit if we accept our own eyes and ears and start moving towards meaningful habitat management, away from this endless picture chase and towards an attraction and netting attempt.
If the committee is going to show actions inconsistent with it own conclusions: the species persists but has a low detection function but the USFWS is not setting aside any Critical Habitat and the various private and public entities are not going to do any meaningful habitat management then we must start reacting.
FV
In Patti Newell's study, 3 of 14 PIWOs netted and fitted with radio transmitters over two study seasons died within 45 days of capture. In addition, one nest was abandoned when a male was netted during the incubation period.
Moreover, even with radio transmitters, PIWOs were difficult to locate, and Newell concluded: "In general it was not worthwhile to transmitter birds for foraging observations in Louisiana."
This is, admittedly, a small study and a small sample size, but leaving aside the practical issues surrounding capturing birds that are extremely difficult to locate, let alone photograph, the risks seem unduly high, and the potential rewards, uncertain at best.
You are right FAV, we do need to just conserve the land and properly manage it. In that way the bird's population would rise and it is likely that a nesting pair would be found eventually for further studies, if not there would be sightings, enough that can give a population estimate, probably a low, but an estimate nonetheless. Then again the land isn't going to be conserved unless a photo does come out, in which case we have to get the photo. Because, according to the skeptics the bird is extinct unless a photo comes out, in which case why would they conserve land that would benefit the IBWO when it could be used for commercial development or habitat conservation for other species, not requiring IBWO type habitat.
Let me know if I am wrong. I do like the wearing red, black, and white instead of camo.
The studies mortality rate for PIWO is close to the expected rate for 14 random control PIWOs that were not netted. The result is insignificant although the 45 days must be explained. Also one would not net IBWOs in the breeding season....field work would be synchonized for least impact.
Since they were adults of unknown age (or do we have ages?) we must assume a mixed age structure. Using an average age of 5 years for birds captured gives an average remaining life span of 5 years. In 2 years you should lose 2 to 3 birds. There is even some chance of losing 4, 5 or more birds in 2 years in a control group that was not captured.
There could have been 2 to 4 birds that were already in the 7 to 9 year old cohort in the N = 14. Older birds are less fit and have less reproductive capacity anyway.
An IBWO that has lived 9 years has most likely passed on any of its unique genes. So we wouldn't lose hetergygosity necesssarily for the remaining population even in the rare event a bird was lossed.
Why the PIWOs died within 45 days needs to be explained. If they are dying several days after capture its not direct stress from capture but reduced survivorship due to the transmitter or the actual field tracking methods reduced the fittness of the birds in some way.
An IBWO in the hand and radioed would provide all types of incredible viability,ecological and population data and possibly lead one to a nest. One capture could directly lead to the location of several more birds.
By the way Sonny Boy was handled twice, jumped out the nest to fall to the ground and was banded. He made it for several months at least, post disturbances, capture and handling.
So two handlings for IBWO with no problems.
Regardless netting should be looked at and quantified.......and weighed against all this milling about and distrurbance during the nesting season coupled with ongoing corridor loss in the SE.
We have little to show for 5 years. Are we happy with the status quo?
tks Fv
In Newell's study, one captured bird was killed by an avian predator approximately 27 days after capture. The other two birds were also apparently killed by avian predators, one twelve days after capture, and the other approximately 43 days after capture. I think this at least raises the question of whether the transmitter itself increases vulnerability to predation.
Newell observes: "woodpeckers were very difficult to relocate, even with telemetry" and concludes that the use of transmitters is not worthwhile. Thus, even if netting/transmittering were possible, and even if the risk were relatively low, I don't think it would be justified, given the current state of knowledge.
Mark, do you have a link to the Newell abstract and article?
Also do you have the right study? Noels study et al. had a suprisingly similar mortality result that you attribute to the Newell study.
Noel-- Abstract - Four of 13 radio-marked individuals were depredated in the lower bottomland habitat:
perhaps dispersal or mate searching is very dangerous
in this environment.
Note these 3 authors do not attribute the mortality to the transmitters but just hypothesize baseline mortality.
Newell (per you) and then you say "woodpeckers were very difficult to relocate, even with telemetry" and concludes that the use of transmitters is not worthwhile. Thus, even if netting/transmittering were possible, and even if the risk were relatively low, I don't think it would be justified, given the current state of knowledge.
My response is to be cautious in rushing to conclusions and making interspecific generalizations.
Adult IBWOs are repeatedly referenced to have no observed animal predators. Its more than premature to assume the same predators can harm the twice as heavy, and much more powerfully protected IBWO. The IBWO is a quicker flyer also.
In addition I am not sure in these studies whether the best/lightest transmitter was used. Regardless the weight would be negligible to an IBWO.
Newell concludes per you "the use of transmitters is not worthwhile."
She may have meant they are not worth it for studying PIWOs. IBWOs are a whole different animal...........if you have to stay in the field for 2 weeks to get one data point on an IBWO...... its worth it.
You say netting is risky under the "current state of knowledge".
The current state of knowdledge to many is the bird is either extinct or close. Any you are worried about netting one bird?
Accepting the status quo has risks which you completely gloss over.
Jacob, said red and white outfit rather than camo sounds good.
If people want to dress like Santa Claus thats up to them..not sure what Kulivan or a male IBWO will think but maybe a female with a tongue ring will show looking for something different.
tks Fred
NJ
Here's a link to Newell's article:
http://tinyurl.com/2vlcq28
The material on radio transmitters is in the last section.
Tks Mark. Both studies noted about the same mortality.
No author or any of the many supporters of either study even mentions your strong inference that mortality was caused by the study or components of the study (transmitters-increased predation). In fact one study is silent, inferring it was nominal, and one opines the mortality rate is caused by the hazards of the bottom land habitat.
Like you I do not rollover to omissions. For example they do not mention if they were in the exact areas of the birds that met mortality on the surmised day of reckoning. If they were then this could mean distracted and flushing birds due to the study suffered unnatural levels of predation. The researchers were collecting many types of data sets and this can lead to to excessive disturbance. Correctly designed IBWO studies should and would not push the birds this hard.
It also noted that these captures and the studies were done during the breeding season. IBWO studies we have been involved with tried to avoid that season and a netting attempt would not be done in the breeding season.
Its ironic that this is exactly what some feel has been done to the IBWO during the picture chase .....collecting of multiple data sets, banging out aggressive sequences of double knocks in prime habitat of known or suspected birds, constant presence in a range, the probable pushing birds off range, helicopters, etc.
Netting is a disturbance but do not be fooled that the running around in the woods the last few years is not without cost.
Other points--- The Newell study involved transmitters weights right at or exceeding the recommended maximum weight for Pileateds. For an IBWO study the transmitter would weight much less than the maximum weight with no effect on this much larger species.
In addition the Newell study had localized predation events...one pair was taken on different days in the same general area. This does not strongly support that the transmitters contributed to predation but rather a predator in that area got an anecdotal liking in that pairs range for Pileateds.
In other words all ~ 14 PIWO had transmitters but only 2 pairs (3 birds) and ranges were predated upon. Transmitters, if a serious problem, could be expected to cause more evenly distrubuted and widespread predation than just some of the birds in only 2 territories, leaving the other other 10 birds in 5 territories unscratched.
tks Fv NJ
Tks Mark. Both studies had nominal mortality.
No author or any of the many supporters mentions your strong inference that mortality was caused by the study or components of the study (transmitters-increased predation). In fact one study is silent, inferring it was nominal; one opines its caused by the hazards of the bottom land habitat.
Like you I do not rollover to omissions. They do not mention if they were in the exact areas of the birds that met mortality on the surmised day of reckoning. If they were then this could mean distracted/flushing birds suffered unnatural levels of predation. The researchers were collecting many types of data and this can lead to to excessive disturbance. Correctly designed IBWO studies should and would not push the birds hard.
Note that these captures and the studies were done during the breeding season. IBWO studies we have been involved with tried to avoid that season and a netting attempt would not be done in the breeding season.
Its ironic that this is exactly what some feel has been done to the IBWO during the picture chase .....collecting of multiple data sets, banging out aggressive sequences of double knocks in prime habitat of known or suspected birds, constant presence in a range, the probable pushing birds off range, helicopters, etc.
Netting is a disturbance but do not be fooled that the running around in the woods the last few years is not without probable cost.
Other points--- The Newell study involved transmitters weights at or exceeding the recommended maximum weight for Pileateds. For an IBWO study the tmitter would weight much less than the max weight with no effect on this much larger species.
In addition the Newell study had localized predation events...one pair was taken on different days in the same general area. This does not strongly support that the transmitters contributed to predation but rather a predator in that area got an anecdotal liking in that pairs range for Pileateds.
In other words all ~ 14 PIWO had transmitters but only 2 pairs (3 birds) and ranges were predated upon. Transmitters, if a serious problem, could be expected to cause more evenly distrubuted and widespread predation than just some of the birds in only 2 territories, leaving the other other 10 birds in 5 territories unscratched.
tks Fv NJ
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