A reader pointed out these words from Nancy Tanner in a
1999 article by Julie Zickefoose (the bold font is mine):
We went back down at Christmas time of 1941 because he wanted to see what was happening there. There were still five ivorybills, and we spent two weeks down there. The bark [from their workings] peels off and falls on the ground, and that's how you find where they are. You could hear them [calling] a mile away, it seemed. They were extremely loud. Very loud. The pounding was pretty darn loud, too. They are a very, very conspicuous bird. They impressed me as being extremely large and gorgeous--so much white is showing. We had located one roost hole, so we were relatively close, sitting quietly on a log in the dark, soaking wet in the swamp. The bird is the last of the woodpeckers to come out [in the morning]. He climbed to the top, pounded, and then called; pounded and then called, and the female flew over next to him, and with a great racket they flew off.
The reader added this comment:
Notice how, time after time, people marched in and got great looks at Ivory-bills. No big teams, no remote cameras, no GPS, undoubtedly no camo and ghillie suits. There was no need to debate whether they'd seen the bird, no need to interpret evidence, it was obvious they'd seen the birds.
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17 comments:
These historical accounts are so telling. They are true and were 100 percent conclusive. It was simple....here are the birds....here are the photos...etc. Black and white. This was in the early 40s, we have come a long way in technology, manpower for searches and funding...and no conclusive evidence after two years now. That is disheartening.
I don't know why we expect a bird that has not been hunted for the last 60-80 years to have suddenly become extra wary. Deer populations that are not hunted for just 10 years become tame and approachable, are birds that different?
But then I go back to the fact that there have been sightings of IBWO by individuals that should know the birds. I read one (unpublished) from a birder that stumbled upon the search team in 2005 (pre-announcement), and had his own sighting where he saw the bill AND the white trailing edge and admitted to NOT seeing the other field marks (which to me indicates honesty). and he is actually a BIRDER! And yes, that DOES make a difference. Birders KNOW what to look for, and they pay attention to details.
So where does that leave me? I'm definately skeptical of the video, but I also think there may be 1-2 widely ranging IBWOs in Arkansas.
could it be that the singer tract birds had no where else to go making them easy to locate? If ivory bills still exist it seems they are able to roam more but it is disheartening we cannot find any roosting holes to study the birds.
Yes I'm changing my thinking towards skeptic on a daily basis.
Although I suppose a confirmed sighting now would mean the nesting area has also been discovered. So Cornell might just keep that a secret.
On the other hand, this bird only shows itself for 1.2 seconds, so ID'ing the bird is difficult but collecting it for a trophy would be downright impossible. :-).
Afterall, the human response time is something like .75 second.
If the sounds travels for 1/2 to 3/4 of a mile, and there must be several fairly contiguous ranges of nesting pairs for species viability...then
there exists an area at least 30 square miles or probably more.
Where for IBWs to have survived, in this area there must be calling woodpeckers that can be heard in most sections of this 30-60 square mile area. This assumes that the "loose colony" evidence presented by Tanner is still valid today.
So that's a big chunk of land to have missed. As Tom points out, the transects probably could not have missed the calling IBW.
Here's the logic:
You need at least 10 nesting pairs
for viability.
They are likely to be found in adjacent territories so different family offspring can find each other and mate to prevent inbreeding.
And Tanner's evidence corroborates this.
6 square miles is the likely territory in our quasi-suitable habitats.
You need about 30-60 miles, therefore of semi-contiguous territories.
There must exist such a chunk of land, the size of an average county
where these birds have avoided the human ear, because in most parts of this chunk of land, IBWs could be heard and easily found by their noise (also corroborated by Nancy Tanner), though sometimes it would take them several HOURS to locate the birds.
No such IBW areas have been located despite 61 years of searching.
And 3 years of intensive search.
So either the birds are numbering only 2-7 birds scattered all over the gulf states and not semi-colonially, or we've been
extremely unlucky and missed a bird
for years that never took the Tanner's more than 1/2 day to locate. And lets remember that the Singer Tract was a pretty good area yet the nesting success there was poor and numbers were declining even before the woods were cut down in
1944.
Paul - New Paltz, NY
...his own sighting where he saw the bill AND the white trailing edge and admitted to NOT seeing the other field marks (which to me indicates honesty).
Good post. But it also indicates to me he had a brief look. Brief looks, time after time. The kind of glimpses which result in mistakes by honest people.
If we were talking Bald Eagles, I'd expect reports of huge raptors, black, with all-white heads AND tails. Not just reports of glimpses of big raptors with a white tail.
It's not completely accurate to assume any species which is not hunted will become less wary in its behaviour. Especially in bird species, this type of behaviour can be quite genetically ingrained.
The real problem with the theory of the wary species, as I see it, is that it must necessarily be predicated upon the idea that a pre-existing subgroup of extra-wary Ivory-billed Woodpeckers has always existed, escaping easy detection and somehow surviving in marginal habitat all these years. In a vacuum, this theory is not so outlandish, but in context, it is quite far-fetched. The early ornithologists were by no means rubes, and for such a subgroup to have existed without detection long before the most wide-spread of habitat destruction stretches the limits of justifiable rationalization. Indeed, far simpler explanations exist, and must necessarily be considered more likely.
There is also a possibility that the bird has always been more wary than was thought, and that the population density was in fact considerably higher than estimated, with large numbers of birds being overlooked. Only the birds who were in more a noisy mood or time of year would have been noticed. It is also possible that the very very conspicuous bird description applies primarily to family groups and breeding pairs (outside of the incubation season probably). Hence lower densities and more solo birds mean quieter birds. Regardless, it remains that sightings by seemingly reliable observers have persisted over many decades. When was the last time a reliable observer reported a sighting of a passenger pigeon, great auk, or carolina parakeet? I have to agree with J. Jackson that it strains credulity to pass off ALL of these sightings as incorrect.
Most woodland birds are seen in brief glimpses most of the time. Heck, most of the pileateds I see are a brief glimpses and flyovers. If there were only one pileated left in Tennessee, I doubt it would be seen very often, and then usually as a brief glimpse. It might not call or drum very often either, given the absence of conspecifics to call and drum to. Let's hope we never find out!
In a fantasy world decades down the road when successful resoration efforts have lead to growing breeding populations of the ivorybill in six different well-protected and managed reserves, we may well discover that in the right habitat and at the right time, they indeed are noisy and very very conspicuous. But for now, in the real world... we ponder, confused.
Bill Pulliam
"Especially in bird species, this type of behaviour can be quite genetically ingrained."
That may be so but wouldn't the population of birds be such that this trait could be passed along over time? The IBWO was never really that abundant in the first place. The birds according to Mrs. Tanner still exhibited none of these "wary" traits to warrant this assumption. For them to somehow aquire this over the last 60 yrs. is really stretching things.
Just think why would a bird who relies on drumming and calls to attract a mate suddenly "clam" up?
It goes against everything "woodpeckery" for lack of a better phrase. What benefit would that provide the species if there are so few of them left?
I think several folks have made some good points - pro & con - here. I'm not defending the assertion but I'd like to read some feedback on it. The "wary bird" idea, where hunting created strong selective pressure for wariness that was against type for IBWOs, is hypothetically plausible. The question that is in my mind, though, is when did that selective pressure end? Were IBWOs still being hunted during the Singer area study? If hunting pressure remained - concurrent with habitat destruction - ok, maybe (strong reluctance here). However, if hunting pressures had largely stopped by the '40's-50's, the selective device would be absent. Wary birds wouldn't have enjoyed any more selective advantage over naive birds. Indeed, I could see a situation where, in the absence of hunting as a selective pressure on sub-populations of wary & naive birds, that the wary birds would be at a disadvantage. A bird whose "wariness" suppressed its mating "advertising" behaviors (calls, displays & other conspicuous actions to attract mates) would seem to be distinctly handicapped in competition for mates/territory against the naive birds' native tendency to "if you have it, flaunt it". Another question (not posed rhetorically to argue against the idea): are there any collections of observations that would give some idea as to how many generations of a specific selective pressure would be necessary to make a given bird population reverse its behavior to behave "against type", so to speak? Maybe there is; I don't know, but I'd love to read more about it. It could change some of my skepticism of the "wary bird" concept.
On hunting and wary Ivory-bills:
Ivory-bills were hunted from prehistoric times up until the 20th century; no doubt about it. It is clear that the last surviving birds, carefully observed, were not particulary wary. (Nancy Tanner, etc.) So countless generations of human hunting pressure hadn't caused the IBWO to become unusually wary. As far as we know, no person has shot an Ivory-bill since 1932: http://www.nature.org/ivorybill/about/history.html
1932: Mason D. Spencer, an attorney and state legislator from Tallulah, Louisiana, shoots an ivory-billed woodpecker in the Singer Tract swamp forests of Madison Parish to prove to state wildlife officials that the birds still exist in the area.
(Please note that although it was extremely unfortunate that he killed this bird, he was able to go out, find and shoot one.)
So the birds were not particularly wary AFTER selected pressure ended.
Based on known science, and common sense, the current birds, if any, should not have become any more wary of humans. In fact, they should be less wary.
Almost all arguments I've seen regarding the wariness of these birds assumes that the Singer Tract birds were absolutely, positively the last Ivory-billeds in the U.S.
Granted, that's the last confirmed population, but if you give any credence to the sightings from Florida in the 1950s, then it seems likely there were in fact other populations at the time Singer Tract was logged. It's also conceivable that there were a few small populations elsewhere.
If the Singer Tract birds that Tanner and others observed truly were the last Ivory-billeds, then assuming any survivors became more wary since 1944 is probably highly unlikely. However, there may have been much more variation in wariness than what Tanner observed, and that range of variation may have existed long before Tanner began his work.
From what I've seen, there seems to be just as much anectodal evidence of people having trouble finding Ivory-billeds in areas where they were known to exist at the time as there is of those having no trouble, including Tanner. [But I'm too lazy to track down that stuff right now. :) ]
This whole discussion is missing much simpler aspects of animal behavior. The Ivory-billed Woodpecker was evidently a social species, as evidenced by the large number of sighting of the bird in groups and pairs and the frequency of social vocalizations. The behavior of a social species is highly dependent on social structure, which in turn is highly dependent on population density and habitat quality. There is in fact little reason to expect that scattered individuals of this species in fragmented habitat would behave in the the same manner as did family groups and higher density populations in large continuous environments. There is no need to invoke hunting pressure or genetic changes.
But whether a species is 'social' or not doesn't necessarily have any influence on how wary it is to man.
"But whether a species is 'social' or not doesn't necessarily have any influence on how wary it is to man."
You missed the point. The point is that their behavior, including vocalizations and tendency to remain within a smaller home range, are likely to vary depending on population density. The birds might not be "wary" so much as just "quiet." In a forest environment that is all that is required to make a bird difficult to detect.
But remember, as noted here earlier this week, the last confirmed Ivory-bill in 1944 was a lone female that was NOT quiet. It kept calling and calling, but got no answer.
Another crucial point on wariness: With the remote cameras, big team, camo and ghillie suits it would also take incredible (perhaps unbelievable) LUCK for an Ivory-bill not to have landed and fed within sight of one of the remote cameras or searchers armed with a camera. It sure isn't wariness that's prevented such chance encounters.
"You missed the point."
The reader eloquently makes the point that the rarer a species is, the harder it can become to detect. But, I think the actual point here is, when you find an individual, how easy is it to study and confirm the identification.
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