Monday, December 31, 2007

What are the odds?

Part 1:

On 6 December 2007 at about 8PM, in the midst of an intense winter storm, a resident of Lilllooet, BC heard a thump on their front door. Thinking the dog wanted to come in, they opened the door to find a strange bird lying on the front porch. It later died despite their best efforts, and it turns out to be a Cook's Petrel (although similar species still need to be ruled out)! This is the first for BC and for Canada.

Lillooet is west of Kamloops, in southern interior BC. It is over 100 miles to the nearest salt water, and at least 250 miles to the nearest open ocean where a Cook's Petrel would be "comfortable". How many were blown into BC and simply perished in bogs and lakes? Maybe only one, but what are the odds that the only one happened to crash into the front door of a house? And on top of that a house where the residents would take enough interest to report it?

Part 2:

In early December 2007 it was reported on the OregonBirds listserv that a Jacksnipe had been shot by a hunter in November - a first record for Oregon and only the 6th for North America of this secretive and cryptic species. But then it was discovered that the same hunter shot a Jacksnipe in the same area of coastal Oregon in late October 2004 , making this the 7th for North America.

How many other Jacksnipes have been shot and never reported? How many are wintering along the Pacific coast of North America? Maybe none. But what are the odds that one snipe-hunter, in a single patch of coastal Oregon, could personally find about one-third of all the North American records of this species?

Part 3:

On 23 December 2007 I went on one of my infrequent birding trips to Cape Ann, Massachusetts with my son and two friends. I was aware of recent Slaty-backed Gulls in Illinois and Pennsylvania, so my expectations were up, but it was still a shock to see a Slaty-backed Gull in Gloucester Harbor - the first ever for Massachusetts. I even thought that "the" bird an hour later had a very different looking bill color, and the next day Rick Heil was able to confirm that there were indeed two Slaty-backed Gulls in Gloucester. Most amazing, just an hour or so after I saw the first one in Gloucester, Wayne Petersen and Dave Larsen found another individual on Cape Cod (they thought they had a first state record, only to find that theirs was the second ... or third, by a matter of minutes - Ouch!).

How many other Slaty-backed Gulls are scattered around the eastern US? Maybe only these few. But what are the odds that the very-thoroughly-birded state of Massachusetts would suddenly have three records? Interestingly, at Gloucester and Cape Cod, the Slaty-backeds coincided with an unprecedented invasion of hundreds of Bohemian Waxwings. It seems bizarre to even suggest that movements of these species are related, but could it be just a coincidence?


And now we enter a new year filled with possibilities....

Thursday, December 6, 2007

Calendars and columns

I was in Washington DC recently and signed some calendars at my cousin's flower shop in Mount Airy, Maryland. So if you've been thinking about getting a calendar and you'd like one that I've signed, you can order them here.

And my new Birder's World column about identifying songbirds by flocking habits is now available online here.

Perspective on a mystery bird

Our perspective and the assumptions and decisions that are triggered by that point-of-view, strongly influence how we perceive the world around us. In short, what we see often depends on how we look at it.

This classic drawing looks like a frog sitting on the edge of a pond...

but rotate it ninety degrees and it turns into a horse's head!

This horse/frog drawing comes from a generic internet source and I assume it is public domain.
If not please let me know, and if anyone knows the artist or original source I'd like to give credit.

We can all remember times when we've experienced this kind of perceptual flip-flop in real life, insisting one thing is correct only to realize in a flash that our underlying assumptions - and our conclusions - were wrong. It certainly comes up a lot in bird identification. A flash of what "could only be" a male Yellow-headed Blackbird resolves into a Common Grackle holding a corn chip; or a carefully-studied Western Sandpiper turns into a Dunlin when it walks next to a much smaller Least.

Clear photographic examples of this are rare, but one such example is this mysterious photo of an apparently black-faced bird taken in late September 2007 by an automatic Wingscapes birdcam and discussed on the Birdcouple blog, with most viewers suggesting either a Carolina Chickadee or a Common Redstart (a Eurasian species not previously recorded in North America).

Photo by Warren and Lisa Strobel. Used by permission.

We probably all look at this picture and assume, quite reasonably, that the bird is holding it's head in a normal position looking to the left and slightly down. And in the image below I've zoomed in and taken the liberty of adding the outline of an eye in about the right position to fit this assumption. In this case the pattern of black face, pale crown, pinkish-buff underside, etc. is a pretty good match for Common Redstart. There are lots of details that are not quite right, some of which have been mentioned in comments with the original blog post. Many experienced birders will notice the details, or simply note that the location is very unlikely for Common Redstart, and will step back to look for another explanation. (If you think the eye looks like it isn't in quite the right place, I can assure you that I moved it around in photoshop and this was the best placement I could find. The eye just doesn't fit this way, which is another clue that the black pattern and head shape is not right for Redstart.)

Below, again, I've taken the liberty of adding a dark spot, this time to show where I think the eye actually is (and a helpful arrow to point it out). I think the head is rotated ninety degrees and the bird is looking up at the sky with one eye, so we're seeing the black throat, and the white band on the upper edge of the head is the "cheek". With the eye in this position the bird's head plumage is a perfect match for Carolina Chickadee. Other details also fit and give no reason to question the ID, and the species is common in the area where the photo was taken.

So I agree completely with the few respondents who have already suggested that this bird is a Carolina Chickadee with its head turned. This particular identification pitfall might never come up in field observations, when we would be able to see the bird move and quickly correct our error, but lots of similar things do happen under field conditions. This story demonstrates that there are nearly infinite possibilities for misidentification, and shows how one misleading glimpse can trigger assumptions that set us firmly onto the wrong path.

Tuesday, December 4, 2007

Redpoll subspecies

If identifying Hoary Redpoll is not enough of a challenge for you, maybe you'd like to look for subspecies of Hoary and Common Redpolls?

First, check out this map from the Canadian Atlas of Bird Banding.

This shows selected western band recoveries of Common Redpolls, and the obvious suggestion is that some of the Common Redpolls being seen in the east right now might be coming from Alaska! Troy (1983) shows a map with a similar pattern, including a redpoll that traveled from New Hampshire to Barrow, Alaska, and another that traveled from Michigan to Siberia. Lots of redpolls also come to the eastern US from the north or northeast, but we should not assume that we are only seeing redpolls from the nearby subarctic regions.

Both species of redpoll are represented in Greenland and Baffin Island by larger and more distinctive subspecies. These "Greenland" Hoary Redpolls are large and very pale, while the "Greenland" Common Redpolls are large and dark. An excellent summary of status and identification is in Pittaway (1992). Greater Common Redpoll can appear in the eastern US in significant numbers some winters, outnumbering Hoary (Pittaway 1992, Wetherbee 1937). Hornemann's Hoary Redpoll is the rarest subspecies in the US, but has been recorded at least south to Maryland and west to Michigan.

Common Redpoll Carduelis flammea
Southern C. f. flammea
Greenland (Greater) C. f. rostrata

Greater is distinguished from Southern by:

  • larger size
  • darker color
  • larger bill with curved (bulging) culmen
  • said to have more upright posture and harsher calls
Hoary Redpoll Carduelis hornemanni

Southern C. h. exilipes
Greenland (Hornemann's) C. h. hornemanni

Hornemann's is distinguished from Southern by:
  • larger size
  • even paler color
Some photos and discussion of Greater Common Redpolls from Toronto already this winter are available here. And a detailed discussion with photos of specimens by the Maryland/District of Columbia Records Commmittee is here (beginning on page 16).

Other references:
Pittaway, R. 1992. Recognizable Forms: Redpolls. Ontario Birds 10(3): 108-114

Troy, D. M. 1983. Recaptures of Redpolls: Movements of an Irruptive species. J. Field Ornithol., 54: 146-151.

Saturday, December 1, 2007

Redpoll Identification

Some updates 4 and 6 December -
check out Jochen's comments and blog post here

With the predicted superflight of finches beginning to develop (1st ever Common Redpoll in New Mexico last week) more and more questions are coming up about finch identification.

Hoary Redpoll, although always less numerous than Common south of the Arctic, is probably more numerous than reports indicate. Identification is very difficult, requiring close and lengthy study, and observers are usually conservative on this ID, so lots of darker Hoarys are never even picked out, possible Hoarys are never confirmed, and lots of passing flocks are simply reported as Commons (1).

If you have a chance to study some redpolls and want to look for Hoary, here are some tips:
  1. The first step is simply to scan the group looking for a paler bird. But by just looking through a flock for paler color you will miss a lot of Hoary Redpolls. With practice you should begin to look for the specific types of paleness listed below - a "frosty" look to the upperparts or wings, a whiter breast, a pale rump, etc.
  2. Once you've found a pale redpoll, check the breast color - If it has pink on the breast it's a male (most 1st winter males have pink on the breast according to Pyle 1997), and identification of males is generally a little easier, but since males of both species tend to be paler than females, a male Common can often stand out as the palest bird in the flock. A male Hoary should look really pale. If there is no pink it's a female (or possibly an immature male), and identification will be more challenging, but since females of both species tend to be darker than the males, the fact that you've picked out a pale female from the flock is promising.
Then check details in no particular order, depending on what part of the bird you can see well, and try to make direct comparisons with birds of the same plumage type:
  • the scapulars should be paler with frosty whitish edges on Hoary
  • flank streaking should be sparse and narrow on Hoary
  • undertail coverts should be white or with only narrow streaks on Hoary (female Hoary often have narrow shaft streaks not as broad as on Commons, and male Common can have no streaks)
  • rump should be mostly white on Hoary, whiter on males (but male Commons can also have a noticeably pale rump)
  • the bill should look short and small, with fluffy nasal bristles covering the base of the upper mandible and making the forehead bulge a bit (but Commons also have tiny bills, you have to study some Commons at close range before you will feel confident using this feature)
  • The pale edges on the wing coverts and secondaries should be broader and whiter on Hoary (but this is variable in both species and, as with all of these clues, it's important to compare birds of the same sex) (2)
If most of these features line up with Hoary, I think it's safe to make the call. It's still subjective and really tough, so it's best to look at a lot of redpolls and get a sense of the variation before you start labeling them, but it looks like there may be plenty of redpolls to practice on this winter!

At this link you can see photos of a recent Hoary and accompanying Commons in Indiana by Peter Grube, showing the features well.

Good luck!

1) A reader suggests that many people are not as conservative as perhaps they should be, and simply slap the "Hoary" label on any noticeably pale redpoll. I agree, but I also think that many true Hoarys are overlooked, so it may actually be that many birds reported as Hoarys are not, but an equal or greater number of real Hoarys are overlooked!

2) Other features that have been mentioned and that might be worth watching for and testing (but many of these are very subjective and my impression currently is that these are less useful than the ones mentioned above):
  • a smaller and brighter red "poll" on the forehead of Hoary
  • less dark color on the throat and lores on Hoary: more restricted and not as dark (but appearance varies with angle of view)
  • Hoary overall larger and fluffier (but note subspecies differences in size)
  • neck appears thicker on Hoary
  • fluffy "leggings" on Hoary
  • A tendency for Hoary to raise tail when foraging on the ground
  • relatively longer tail
  • there may be subtle differences in calls, and this deserves more testing, but singling one calling bird out of a flock is usually impossible. The larger "Greenland" subspecies also may have different calls.

Tuesday, November 20, 2007

More on windows and birds

After a week of pretty good success on the windows, today was cold with light snow, and the bird feeder was very active. I realized last week that one of many variables I need to consider when I record bird-strikes-per-hour is bird activity, but I haven't tried to record that yet other than excluding long periods when no birds were present. Obviously, if there are few birds visiting, there are fewer chances for collisions. At the other extreme, like today, when the feeder gets crowded there seem to be birds in the air all the time - hovering and jostling for a perch. In these conditions there are many more chances for collisions.

So today I started observing and recorded 6 window strikes in 1 hour 40 minutes - about one every 16 minutes. Thinking that this was happening because of the faded highlighter I reapplied the lines, and in the next 3 hours 30 minutes there were 8 strikes, or about one every 33 minutes - about half as frequent but still pretty distressing and not really a significant improvement. However (one can always find a hopeful angle) five times during that period birds flew in and landed scratching at the windowsill. Maybe these were birds that would have crashed into the glass, but recognized the danger at the last second and fluttered harmlessly down to the windowsill.

A physics lesson
Some of my assumptions about UV light and what birds perceive were wrong, and I've been educated by some posts on the NikonGear UV photography forum, and some follow-up research. What we see under the black light is fluorescence. Certain compounds are "excited" as they absorb UV energy and then - when electrons return to their normal state - they fluoresce: releasing energy as light in the visible range. So this is why day-glo colors appear intensely bright in sunlight - UV energy from the sun causes fluorescence, and the colors actually glow.

Therefore my experiment with the black light has very little to do with UV other than as the light source. The black light is good for finding fluorescent things, and fluorescence begins with UV absorption, but many things absorb or reflect UV without fluorescing and we simply can't see it. A search for UV-visible substances to mark windows would require much more specialized equipment. You can see some really cool examples of UV photography here.

The fluorescent highlighter should still be visible to birds, because the fluorescent ink will simultaneously absorb UV and release visible light. But the visible fluorescence in daylight may be about as obvious to the birds as it is to us (i.e. not very). So if the highlighter works it may work largely because it absorbs UV, or maybe the combination of absorbing UV and releasing visible light is more obvious to the birds. Either way, that process requires a UV light source, and another issue that I think might explain today's poor results (still searching for that hopeful angle) is that UV wavelengths are blocked by clouds. Apparently "thin" clouds allow about 60-80% of UVA (the longest wavelengths of UV and the range that birds can see) to pass through, but thicker clouds block most UVA. So with little or no UV, such as during today's snowstorm, the highlighter marks would neither absorb UV nor release fluorescence, and the birds' vision would rely on the same visible spectrum that we see. If this is true then all efforts to use UV-related markings on glass will only have limited effectiveness (but don't take my word for it). So I'll have to note weather conditions in the future as I record window strikes to see if the highlighter is more effective on sunny days.

By the way, window glass blocks some shorter UV wavelengths, but at least 90% of UVA apparently does pass through ordinary glass.

So what does this mean?
Well, clearly the highlighter is not the "magic bullet" that everyone is hoping for. I'm still anxious to hear from others who have tried it. So far I have two responses indicating that it works, and I'd like to hear more, but if anyone has tried it without success I'm especially interested to hear about that.

If it does work, it will presumably work best in sunlight, and worst in low light or on overcast days, and unfortunately bird feeders are generally most active at those times.

As I said previously, we can keep trying to find ways to make the reflection in the glass look unattractive to the birds, but there will always be things (like hawks) that look even less attractive and cause birds to try to escape through the window. To truly prevent window strikes will require a barrier such as t
he BirdScreen.

Thursday, November 15, 2007

A Potential Simple Method for "Bird-Proofing" Windows

Update 16 November - There are a couple of points I think I should clarify. First - and I guess this may be clear already - I'm still not convinced this will work, or how well it will work, and it will probably work in some situations better than others, and never be 100% effective since the hard glass surface is still exposed. If you try it please let me know how it works, good or bad.

I should have mentioned the Bird Screen, which apparently does offer nearly 100% protection, and might be the best solution for a lot of situations. I suggest the potential of the highlighter as an easy, cheap, and possibly effective solution, but if you're really interested you should check out the Bird Screen as a proven, reliable method of preventing window strikes.

Update 17 November - It's definitely not 100% effective; I've had two bird strikes in the last few hours, but that's still only two in a total of about 16 hours, which at the previous rate would have resulted in about 20 strikes.

Update 19 November - A potentially serious flaw in the "highlighter method" of preventing window strikes has come up - the UV color fades quickly.
Here (left) is a window just 20 minutes after applying the highlighter and (right) another window after the highlighter has been on for six days. (Both photographed at night with 1 sec exposure, same distance and position of black light). The six-day-old highlighter is not as bright and obvious as the fresh ink, especially to the right in the less intense UV light, so effectiveness for preventing bird strikes presumably decreases. In order to maintain the effectiveness one would have to reapply the highlighter frequently, maybe weekly.

I'm investigating some sunlight-stable UV pigment, but it's said to be less bright, and it's much more expensive and can't be delivered by pen. More on that, hopefully, later.

In the meantime, if you need immediate bird collision prevention try the
Wisconsin Humane Society online store.

Estimates of the number of birds killed in window collisions each year in North America run as high as nearly a billion birds. It's the biggest source of direct human-caused mortality in wild birds. But a simple means to prevent birds from hitting windows on your house or office could be in your desk drawer, or at least as close as your local office supply store, costing only a couple of dollars and a few minutes of your time. This needs further testing, but it appears that an ordinary yellow highlighter can be used to draw lines on the window, and those lines may be visible to birds, warning them away from the window, but are almost invisible to people.

Windows like the one below can be deadly for birds. This is my window with a bird feeder I recently set up. Placing the feeder within one meter of the window prevents the birds from picking up much speed before they hit it, so any bird collisions are supposedly non-lethal, but this reflection was so deceptive that an average of nearly two birds every hour were hitting it in early November - incredible and distressing! I left the feeder empty after a couple of days but kept thinking it would make a good opportunity to study bird-window 'interactions'.

American Goldfinches and a Tufted Titmouse
photo taken automatically by a Wingscapes Birdcam

I live in a house with lots of windows, and I like to keep lots of bird feeders. This is good for me as a birder, but often bad for the birds. Over the years I have tried various methods of making the windows either more visible or less harmful, but sometimes it just doesn't help. Birds fly very fast and at times (for example, when startled by a predator) will try to fly through things they would normally avoid. Occasionally, Cooper's and Red-tailed hawks seem to learn that they can pop around the corner of the house, cause a panic at the bird feeder, and then have easy pickings from under the window.

I found lots of helpful info on the web. Groups like FLAP have good suggestions about how to minimize the danger of window strikes here, and New York City Audubon has a detailed guide to Bird-safe building. Some of that worked for me, but some of it was either impractical or unsatisfactory for my situation. For several years I had pretty good success with simple lengths of white string hanging in front of the worst windows. This cut down on collisions, but did not eliminate them, and the string was unsightly and distracting, tricky to install, and required some tedious maintenance. I wanted a better solution.

Experiment 12 Nov 2007
Hypothesis: Since birds can see ultraviolet wavelengths of light and we can't, it must be possible to add a UV-reflective coating to windows that would make them more or less opaque to birds but still transparent to humans.

Methods: In the darkened kitchen with a black light and piece of plexiglass, my kids and I tested various household products to see what, if anything, might meet the twin requirements of being visible to birds and invisible to humans.

Results: Various juices and cleaning supplies all proved to be non-UV-reflective: Pledge, Simple-Green, Windex, Rain-X, Dawn, Orange Juice, Apples, Shampoo, Conditioner,... all no.
Olive oil, yes! Drops of it look like red curry sauce under the black light, but once it's spread thin the color is so faint it would presumably not be obvious to birds (plus it's messy and hard to see through).
Thinking beyond "fluids" we wondered about dry-erase markers, but no, they don't glow under the black light either.
Then I noticed the brilliant orange light from a supermarket price tag reflecting the UV. I thought of fluorescent colors (duh) and wondered about a thin wash of diluted day-glo paint, then I thought of highlighters. My son found one in the desk drawer, and... Bingo! Under the black light we could draw a pattern of brilliant yellow lines on the plexiglass, but under normal light the lines were almost invisible. Now we needed to test it on an actual window with real birds....

13 November 2007
Here (above) is the window and new bird feeder that had been combining for an average of nearly 2 bird strikes per hour until I left it empty. I've already drawn on the window with a highlighter, but the lines are invisible in this photo. Below is the same window illuminated with the black light to show the grid of highlighter lines (window shades inside are glowing blue). Presumably the birds see something like this. I filled the bird feeder and went inside to observe.

14-15 November results:
As I write this on 15 November, I have spent 11 hours monitoring steady bird activity at the feeder. After nine hours with NO window-collisions, a light rain started. The highlighter markings were getting washed away and a goldfinch hit the window. So I wiped off the outside of the glass and drew new lines on the inside. That's working so far, with no strikes in about two more hours of bird activity. Not enough data to really say anything conclusive, but testing continues....

Markings inside vs outside the glass: The first test was done with highlighter drawn on the outside of the window. That seems to work very well to deter birds but the ink I used washes right off with water. I tested the highlighter on the inside of another window and the markings appear to be equally visible from the outside. So I assume that marking the inside - where the glass is generally easier to reach and the marks will be protected from weather - would be just as effective at stopping bird collisions. Testing that now, and so far so good.

Grid size and pattern: In this first trial I've drawn a rough grid with squares about 2.5 to 3" across. I'll try to test some other designs to see if less marking or different designs give the same benefit. You could be really creative and draw architectural patterns or write 'secret' messages on the glass, as long as you don't leave big parts of the window unmarked. From other research it seems that the "openings" should be no larger than 4 inches high by 2 inches wide, so maybe my grid is about right.

Other inks: It would also be interesting to test other colors of highlighters or other kinds of fluorescent ink or paint. I notice that there are commercially available "invisible" fluorescent inks, the kind that are used for admission stamps at concerts, etc. Those could be even better than the highlighter, being clear in normal light, and there's probably a formulation that would be water-resistant for outdoor use. I'll try to check that out too. But there's almost no disadvantage to the highlighter, and it's so simple and readily available.

Disclaimers: These are preliminary results, and it's possible that further trials won't be quite as successful, but these early results are so promising (and it's so easy and low-risk) I wanted to get this information out there so that other people could try it and hopefully save some birds. The highlighter that I used seems to wash off easily with water, and does not stain the window frames here, but I make no warranty against staining or other damage to windows or adjacent materials that might be caused by following the above instructions.

Let me know how it works for you.

My new Birder's World column

I'm pleased to join my friends Kenn Kaufmann, Pete Dunne and others as a contributor to Birder's World magazine, and editor Chuck Hagner promises that I will "reveal the real secrets" of bird identification. I don't know if everyone's really ready for that, but each of my columns will be a short illustrated discussion of bird identification challenges from a more general perspective. The first one is about using flocking habits as a field mark, the second one - due out in February - will be about wingbars. Currently this is available only in the paper magazine, not on the web, so I can't offer a link to it yet. But I'll be interested in any discussion, comments, or suggestions. You can leave those here, or on the Birder's World forum, or just send me an email.

Wednesday, November 14, 2007

More rare bird news and a correction

The latest Siberian highlight was California's first Eurasian Kestrel banded in Marin Co. CA on 23 October 2007 but not seen again (photos here). About 10 North American Records.

Otherwise, in addition to what I listed previously, a Dusky Warbler and four Eastern Yellow Wagtails in CA, and a Rustic Bunting in BC are the only Siberian birds that I've heard of that seemed to find their way down from Alaska. A little above average, perhaps, but my earlier excitement about watching for Eye-browed thrushes, etc hasn't really panned out. Although there's still time....

A well-seen adult Ross's Gull November 10-11 at Vanderhoof, north-central BC ( the 2nd for BC, with a very late and rare-inland Arctic Tern). There was an earlier report of an adult Ross's Gull in September in eastern Colorado! So this is another species for southern birders to keep in mind.

Probably unrelated to the Ross's Gull, but quite a coincidence in timing, an Ivory Gull was reported on 11 November just inland from Vancouver, BC.

The Green-breasted Mango continues in Georgia, and the Wisconsin bird now survives in captivity. See my previous post about mangos for more.

Correction - I said in a previous post that a Tristram's Storm-Petrel off southern California in July this year was the first ever reported in North America, but there are photos of an apparent Tristram's Storm-Petrel trapped on the Farallons, off San Francisco, CA on 22 Apr 2006 (photo here) and currently under review by the California Bird Records Committee.

Paintings on exhibit

Six original plates from the Sibley Guide to Birds will be exhibited at the Cahoon Museum of American Art in Cotuit, MA now through December 31, 2007 as part of their show "In Fine Feather: Excellence in Contemporary Bird Carving and Avian Art"

Monday, November 5, 2007

"Great White" Heron - not just a color morph

Great White Heron Ardea herodias occidentalis

updated 13 Nov 2007, thanks to all those who have commented publicly and privately. I've backed off a bit from my criticism of the TBRC decision, the more I learn the less clear-cut this seems, although I still think it's at least a good subspecies. Shaibal Mitra sent me a copy of a paper he and John Fritz published in the Kingbird a few years ago, which reaches the same conclusion that Great White Heron is a distinctive subspecies, but points to my book as one of the sources unfortunately labeling the Great White Heron "simply a color morph". Oops, I guess it does. That's not quite what I meant!

This post is about the debate over whether the "Great White" population of Great Blue Heron is "simply a color morph" (TBRC 2006, Butler 1992), a subspecies (Mayr 1956, Meyerriecks 1957), or a full species (McGuire 2002). A few days ago in the first draft of this post it seemed clear-cut, now with additional information from many sources it seems less so. Much of what I've written here has been said before by Mitra and Fritz (2002) and by Tony Gallucci in 2004 on TexBirds here.

Butler (1992) dismisses the white population with almost no discussion, and unfortunately I labeled this the "white morph" in my field guide (Sibley 2000) even though I recognized that it was more than just a color morph. The Texas Bird Records Committee (TBRC) decided in 2006 to drop "Great White" Heron from the state review list, saying that it seemed to be just a color morph and not a distinct subspecies. This decision was apparently prompted by two records of white nestlings in Great Blue nests in Texas - an old photo from Galveston County (presumably from McHenry and Dyes, 1983) and an unpublished 2006 photo from Aransas County showing a white and dark nestling together in a nest tended by two dark adults!

I am fascinated by these records of white nestlings in Great Blue nests in Texas, but I disagree with the TBRC decision. I have always considered Great White Herons distinctive and I can't accept that this is "simply a color morph". Mayr (1956) did some actual research to confirm that "The Great White Herons are not merely albino specimens of Ward's [Great Blue] Heron, but form a mangrove population in the Key West area which differs from Ward's Heron on the mainland not only by the white coloration, but also by shorter plumes and an average larger bill." (some nice Great White photos are here).

Mayr (1956) and Meyerriecks (1957) studied the white and dark herons of south Florida and found mixed pairs, no clear differences in behavior, and subtle differences in morphology. Zachow (1983) found that measurements of Great Whites are significantly larger than Great Blues from the Florida peninsula, which in turn are significantly larger than Great Blues from farther north. Mayr and Meyerriecks both argue that the "Great White" Heron is not a separate species, but they never question the fact that it is a valid subspecies.

Looking at the measurements from a field ID perspective, however, suggests that they may not be as diagnostic as has been assumed. The following graph shows Mayr's bill/wing data in graphic form. Obviously there is lots of overlap between Great White and Ward's Great Blue from the Florida peninsula, even though there is enough difference for most birders to take away the impression that the Great White is a "much larger-billed" bird.
McGuire (2002) in a more detailed study actually does suggest that "The great white heron appears to be a good biological species". McGuire found that although some mixed dark-white pairs occur in the Florida Keys, there are fewer than would be expected by chance. DNA analysis suggests that the herons of Florida Bay and the Keys are isolated to some extent from the Great Blue Herons of the Florida Peninsula. [McGuire suggests that one possible isolating mechanism is time of breeding, with the peak of nesting in the Keys from October to April, and the nesting season on the mainland beginning in Feb-Mar].

The map below shows the breeding range as recorded in the Florida Breeding Bird Atlas. I added the green color to show the Great White records. Note that the green dot far north on the Gulf Coast represents a solitary Great White among Great Blues. The red dot at the upper end of Key Largo might represent one or more nests of true Great Blue Herons or an intermediate "Wurdemann's-type". Interesting to note on this map is the small but obvious gap between breeding Great Blues and Great Whites.

One of the most interesting facets of this is that the dark birds in the keys are intermediate in plumage and known as "Wurdemann's Heron". These are found only in the Florida Keys with Great White Herons, and according to McGuire, Mayr, and Meyerriecks all of the dark birds breeding in that area are typical of "Wurdemann's" rather than the mainland subspecies of Great Blue Heron. So when researchers in the Keys report dark-white pairs and also dark-dark pairs with some white offspring, the dark birds are "Wurdemann's" and not typical dark mainland Great Blues. Among nesting colonies in Florida Bay and the Keys, white birds (Great White) outnumber blue (Wurdemann's) about 4:1 (McGuire 2002).

McGuire shows that "dark" birds in the keys are slightly smaller than white ones, but not significantly, and emphasizes that color of dark birds varies continuously from Great-Blue-like but (always?) with more white on the head (photo here) to mostly white with pale gray wings and back, so that it is not possible to classify the non-white birds into subgroups. In size measurements and in DNA the dark birds of the Keys are slightly but not significantly different from Great Whites, but they are significantly different from the mainland Great Blues (McGuire 2002). McGuire takes the color and size difference as evidence that "Wurdemann's" are intergrades, but it would be helpful to know if measurements are correlated with size. That is, are the birds with the most Great-Blue-like plumage in the keys also the smallest? Assortative mating supports the intergrade hypothesis.

I may not go so far as to endorse McGuire's view that the Great White Heron is a separate species, but there does seem to be plenty of evidence that this population is distinctive and at least somewhat isolated. A vagrant outside of the normal range should be identifiable with a high degree of certainty, and Great White and "Wurdemann's" can be reliably distinguished from albino Great Blue Herons.

Birders in Texas and elsewhere should be encouraged to watch for this distinctive subspecies, and the Texas Bird Records committee should put it back on the state review list. That of course reopens the question of what to make of the white nestlings photographed in Texas. They should not be accepted as "Great White" Herons just because they're white. Similarly, their mere existence does not negate the distinctiveness of true Great Whites from the Florida Keys. The true status of those white nestlings will have to remain a mystery for now, awaiting further study.

It is interesting that white nestlings have been found twice in Texas but full-grown white birds have been seen very rarely there, and only as brief visitors. We still don't know what these white nestlings look like as adults.

Have white nestlings been found elsewhere in Great Blue nests?

White morph Great Blues are also said to occur in Cuba, Jamaica, the Yucatan, and off Venezuela but are apparently smaller than the Keys birds and scarce (not a majority). What do these birds actually look like and what is their status?

Just how big and short-plumed are Great Whites? I didn't do a thorough search but couldn't find a good set of published measurements. I found no published measurements of head plumes, only the repeated assertion that Great White has shorter plumes. So I can't confirm the identification features, only that I have the impression that Great Whites are distinctive, and should be more distinctive the farther one gets from Florida (as the size of Great Blues decreases clinally).

Does it make more sense to consider the variable "Wurdemann's" Heron as an intergrade swarm, or simply as the dark morph of Great White Heron - making Great White a dimorphic, large, short-plumed subspecies of Great Blue Heron?

There are isolated records of Great White Heron nesting north to the Tampa area (Bancroft, 1969; Florida Breeding Bird Atlas map), and nonbreeders wander regularly to northern Florida (not mapped) and less often but still regularly to coastal Georgia.

This map shows the resident range (purple), distribution of vagrant records (green), and general areas of reported occurrence outside the US (yellow). The two red dots represent multiple records at a single location, which might be more likely to represent color abnormalities of local Great Blues rather than wandering Great Whites (Pymatuning Lake, PA: three birds in 1938 and another in 1961); South Holston Lake, VA/TN: single bird in fall 1990, 1991, 1994, and 2002). But in general the distribution of records appears consistent with a south Florida origin. On the other hand, Marshall Iliff (pers. comm.) points out that this is a surprising number of vagrant records given that the total breeding population of Great White Heron is under 1000 breeding pairs.
Aberrant "Wurdemann's-like" herons:
A bird photographed in Washington County, PA in 2004 and present every year since then is clearly not a "Wurdemann's" Heron, and likely a Great Blue x Great Egret hybrid.

Another odd bird photographed in MA in Sep 2005 was clearly a leucistic Great Blue based on size and plumage details, and not a "Wurdemann's". (Thanks to M. Rines for the photo)

Bancroft, G. 1969. A great white heron in great blue nesting colony. Auk
86:141–142. pdf here

Butler, Robert W.. 1992 . Great Blue Heron (Ardea herodias), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online

Mayr, E. 1956. Is the great white heron a good species? Auk 73:71–77. pdf here

McGuire, H. L. 2002. Taxonomic status of the great white heron (Ardea herodias occidentalis): an analysis of behavioral, genetic, and morphometric evidence. Final Report. Florida Fish and Wildlife Conservation Commission, Tallahassee, Florida, USA. pdf here

McHenry, E. N., and J. C. Dyes. 1983. First record of juvenal “white-phase”
great blue heron in Texas. American Birds 37:119.

Meyerriecks, A. J. 1957. Field observations pertaining to the systematic
status of the great white heron in the Florida Keys. Auk 74:469–478. pdf here

Mitra, S. S. and Fritz, J. (2002) Two Great White Herons (Ardea (herodias) occidentalis) in NewYork,Sept-Nov 2001.Kingbird 52 (1):27-34.

Sibley, D. A. 2000. The Sibley Guide to Birds. Chanticleer Press.

Texas Bird Records Committee. 2006. Minutes of Annual Meeting.

Zachow, K. F. 1983. The great blue and great white heron (Aves: Ciconiiformes: Ardeidae): a multivariate morphometric analysis of skeletons. Thesis, University of Miami, Coral Gables, Florida, USA.

New products

Responding to some recent questions:
A couple of readers have asked about any plans for an updated version of my bird guides. This is something I'm always planning for and I look forward to compiling all the new things I'm learning into a new edition in the future. But there are no plans at present to create an updated version of the bird guide. Whether that will happen in two years, five years, or more will depend on a lot of other things.

In the meantime a French language edition of the Eastern Guide was published in Quebec by Michel Quintin in 2006. This was translated by an expert birder - Normand David (with help from Serge Gagne) - who painstakingly read and interpreted every word, so the translation actually offers a lot of editorial improvements and some Quebec-specific tidbits compared to the English language edition.

And while I'm at it, I'll mention the new calendars. Ronnie Sellers Publishing, Inc. has produced a wall calendar, a weekly appointment planner, and a page-a-day calendar for 2008.

Wednesday, October 31, 2007

Green-breasted Mangos in North America

Green-breasted Mango Anthracothorax prevostii

This species is not included in the Sibley Guide to Birds because at the time that I was planning the book there were only two records north of Mexico. By the time I had finished the book there were 7 records (enough to warrant inclusion, if only I had known sooner!). Records have continued to increase with the total as of today up to at least 16 in Texas (through 2006) and single records in NC, WI, and GA. The WI and GA records are both in fall 2007, prompting this summary. Obviously it's a species that should be watched for all over the US.

A report by John Arvin on identification of Mango Hummingbirds from the minutes of the 1995 Texas Bird Records Committee meeting:
Arvin discussed his findings regarding identification of immature/female Mango sp. hummingbirds of Central America and northern South America. Arvin has now visited 3 of the 4 major North American collections with numbers of Mango specimens (LSU, Smithsonian, and Field Museum of Chicago; American Museum of Natural History specimens have not been examined). He examined all specimens of the 3 mainland Mango species which are possibly confused:
- GBMA - Green-breasted Mango (Anthracothorax prevostii)
- GTMA - Green-throated Mango (A. viridigula)
- BTMA - Black-throated Mango (A. nigricollis)
A brief summary of distinctive aspects follows:
GTMA is a scarce hummer of n.e. S. Am. It is rare in collections. Fem/imms are easy to separate because the dark stripe on the center of the underparts is short, extending barely past the throat.
BTMA occurs in humid tropical lowlands. Fems/imms are very similar to GBMA except that the central dark stripe NEVER shows any blue or green iridescence; it is flat black.
GBMA is highly migratory at least in the northern part of its range. GBMA fem/imms have varying amounts of color in the central dark stripe but: No GBMA failed to show at least a little blue or green color (at least a few metallic feathers) in the stripe. Thus, IF a mango is a fem/imm and IF any blue/green iridescence is seen in the dark belly stripe, it is a confirmed Green-breasted Mango. If no color is seen, it may be accepted at least as a mango sp. Based on geographic probability, and the fact that the northern pops of GBMA are migratory and no other pops of any of the other spp. are, it is a virtual certainty that any mango sp. in Texas is a GBMA (barring escaped captive). TBRC members may continue to make their own decisions on how conservative they may choose to view records in which no color in the central stripe is seen.
Arvin could find no other plumage differences that would be useful at distinguishing fem/imm GBMA and BTMA. Apparently the amount of rufous/rusty on the sides of the neck does NOT help; it is quite variable within and between these two species.
North American Records:

Texas 1) - 14-23 September 1988. One female or immature was at Brownsville, Cameron Co, TX. Originally accepted only as Mango species (Anthracothorax species) this record was later accepted as a Green-breasted Mango based on geographic probability after a pattern of other documented records developed. the first record of its genus in the United States.

Texas 2) - 6-27 January 1992. One female or immature in Corpus Christi, Nueces Co, TX.
photo here and here. From TBRC 1993 report.

Texas 3) - 22-27 September 1993. One female plumaged bird, in Falfurrias, Brooks Co, TX. 1995 TBRC report

Texas 4) - 18-20 August 1993. One immature was photographed at Santa Ana NWR, Hidalgo Co, TX. 1996 TBRC report

Texas 5) - 17-20 August 1996. Up to two were at San Benito, Cameron Co, TX, 1997 TBRC report

Texas 6) - 3-8, and 21 November to 21 December 1997. One at Corpus Christi, Nueces Co, TX, 1998 TBRC report

Texas 7) - 22-23 May 1999. One at Los Fresnos, Cameron Co, TX. 2000 TBRC report

North Carolina 1) - 12 Nov - 4 Dec 2000. One immature male in Concord, Cabarrus Co, NC. Article in The Chat here (pdf) photos here and here

Texas 8) - 1-8 February 2001. A male at McAllen, Hidalgo Co, TX,

Texas 9) - 10 July-15 August 2001. A female or immature at Pharr, Hidalgo Co, TX,

Texas 10) - 28 September-18 October 2001. A male at McAllen, Hidalgo Co, TX, TBRC 2002 report

Texas 11) - 23 November 2001-12 February 2002. A male at McAllen, Hidalgo Co, TX,

Texas 12) - 9 September- 23 October 2002 The same male returned to McAllen, Hidalgo Co, TX, TBRC 2003 report

Texas 13) - 22 August-5 December 2004. One adult male at McAllen, Hidalgo Co, TX, photos here

Texas 14) -
20 September 2004-25 January 2005. One (or possibly two) adult male(s) at McAllen, Hidalgo Co, TX, photo here and here and here (labeled Pharr, TX?) and here

Texas 15) -
18-20 June 2005. An imm. bird at San Benito, Cameron Co, TBRC 2005 report

Texas 16). 8-9 July 2006. An imm. bird at San Benito, Cameron Co, TX, TBRC 2006 report

Wisconsin 1) - early Sep - 5 Nov+, 2007. Immature or female at Beloit, WI; photos here and here and here. This bird was captured on 5 Nov 2007 and taken into captivity, details here.

Georgia 1) - 25 Oct - 11 Nov+, 2007. One immature or female at Dublin, Laurens Co. GA; photos here and here and here

TBRC annual reports and minutes can be found here

Tuesday, October 30, 2007

Certainty in sight records

In late August 1982 I walked into the weedy fields at the South Cape May Meadows in search of rare birds. Among many species that I had in mind as possible "prizes" that day was Loggerhead Shrike and, lo and behold, a scan of the bushes ahead revealed a small, white-breasted, dark-masked bird perched conspicuously on top of a slender post - a Loggerhead Shrike!

I looked for a couple of seconds and then quickly moved closer hoping to sit down to study and sketch this rare find, only to discover that it was gone. Not only was the shrike gone, I couldn't even find the post it had been on! In place of both was a Great Egret calmly hunting the grassy edge of a pond.
Such is the power of suggestion. I thought I might be rewarded that morning with a sighting of a Loggerhead Shrike, and I managed to create the vision I desired out of the pattern of shadows on a Great Egret, complete with dark mask, long tail, and the right shape and posture.

If the situation was different and I was only able to see it from a distance for those first few seconds, it's very possible that I would have convinced myself that what I had seen was real and that I would have reported seeing a Loggerhead Shrike. And if anyone had questioned it I would have said I was absolutely certain. After all, I was an experienced observer and I saw multiple diagnostic field marks. What else could it have been?

This is the fundamental problem with all of the recent Ivory-billed Woodpecker sightings. Claims of certainty and lists of diagnostic field marks are simply not as meaningful when they are based on such brief views.

Proponents still emphasize the number of sightings and the fact that some auditory and visual encounters are clustered. They ask "What are the chances that all of those people were mistaken?" Referring to one of his own brief sightings, Geoffrey Hill asks "What are the chances that just as I was misidentifying a Pileated Woodpecker as an Ivory-billed Woodpecker, I would hear another pileated give a double-knock?"

First of all, these questions are spurious and attempt to shift the burden of proof to the skeptics. It is not up to the skeptics to show how all observers could be mistaken. The simple answer is "Yes, that is possible." There is no proof and whether these observations are more likely to be correct or incorrect is simply a debate over percentages.

I would argue that the chances are very good that one misidentification led to another, since these events are not independent. Here's a possible scenario:
An observer hoping to see an Ivory-billed has an ambiguous view of a bird flying away. In the moments after, while processing the flickering black-and-white pattern of the wings and while most susceptible to suggestion, a single double-knock-like sound is heard. The sound (even though it too was ambiguous and was clearly not produced by the bird that flew away) helps cross a decision threshold - that Ivory-billed is likely, that the white really did seem to be on the trailing edge of the wings, and that the bird that just flew away must have been an Ivory-billed.

That decision in turn influences the perception of the double-knock-like sound, which then seems less ambiguous and "must have been" a second Ivory-billed. And as the observer reconstructs memories of the event and adds other subtle impressions to support the identification ("that was no Pileated Woodpecker!"), a circular reinforcement occurs. The retrospective perception of the wing pattern and sound actually change as positive elements are replayed and negatives ignored. The more certain the wing pattern seems, the better the double-knock sounds, which reinforces the interpretation of the wing pattern, and so on.

This may not be exactly what happened in this case, but all of these effects are well-documented in psychological research.

No intentional falsification or fabrication is needed, simply a subconscious selection of evidence supporting the favored conclusion, and a subconscious omission of refuting evidence. This generates false confidence. Once the perception is formed and "confirmed" it becomes nearly immune to question or revision. Claims of certainty and "multiple field marks seen" must be judged in the context of the situation. Longer and better views of a bird require less interpretation and give the observer more information and more opportunity to correct mistakes. Views as poor as all of the reported Ivory-billed sightings are far from certain.

This does not mean they should be ignored, and they have not been ignored. The reported sightings have inspired and guided massive search and conservation efforts in the last three years and before. Sightings should continue to be carefully reviewed and followed-up, but we have to be realistic about the strength of those sight records. If unprecedented search efforts fail to find what a few people glimpsed three years ago, it might indicate that those observers were mistaken.

Tuesday, October 23, 2007

Ivory-billed Woodpecker - status review

In August 2007 the US Fish and Wildlife Service published the Draft Ivory-billed Woodpecker Recovery Plan and invited public comments (the deadline was 22 Oct 2007). I'm posting a slightly edited version of my recently-submitted comments here. Although I'm critical of many aspects of the claimed rediscovery, and some may reject my views outright, I think raising these issues is in the best interests of conservation and birding, and I hope these comments can be constructive in an ongoing dialog. I think this is a very important issue with repercussions far beyond the central question of whether or not the species still exists.

I have been skeptical of the Ivory-billed Woodpecker reports since about two weeks after the announcement in April 2005. This view has only become stronger over time and is based on my thorough study of the published evidence, drawing on my 35 years of experience as a birdwatcher and student of bird identification, and on my experience reviewing countless similar rare bird reports.

I find this Draft Recovery Plan fundamentally flawed, as it presumes that there is an urgent need for action based on "convincing evidence of the species' existence" when in fact no independent review finds that evidence convincing. The 2005 claim of "irrefutable proof" was incorrect; and was based on ambiguous evidence misinterpreted through hope and desire (commonly called wishful thinking). The case for the bird's continued existence rests on a few seconds of extremely blurry video (shown to be consistent with Pileated Woodpecker), a handful of fleeting glimpses by observers steeped in expectations, faint audio recordings that more or less resemble Ivory-billed sounds (among other things), and a belief that all of these possibly suggestive bits add up to a compelling body of evidence (1). None of the evidence stands up to scrutiny; there is no proof. Most importantly, hundreds of thousands of person-hours of intensive search efforts since 2005 - which could have confirmed the sight reports - have not produced any confirmation at all.

Based on such weak and ambiguous evidence, the proposal to spend up to $27.7 million of a very limited budget on efforts to find and recover the Ivory-billed Woodpecker is unsupportable. Hundreds of other species with well-documented needs would be better-served by those resources.

Opinion vs. Science

An important point to understand is that the scientific debate does not directly address the question of presence or absence, only whether the bird's presence has been confirmed. It has not. From the lack of confirmation one can infer absence, but absence cannot be proven. The burden of proof is on those who claim to have found the bird.

Many people apparently hold a positive interpretation of the evidence because of a personal belief in one or more of the sight reports, or a feeling that the combined body of evidence is convincing and that at least one of the many reports must be correct. But the body of evidence is only as strong as the single strongest piece - ten cups of weak coffee do not make a pot of strong coffee. Without evidence that can be reviewed and verified objectively and independently (the scientific standard) the debate is just so many personal opinions.

The only potentially verifiable evidence to date is the brief video recording from Arkansas, but independent reviews have refuted the claim that this shows an Ivory-billed Woodpecker, and even the most generous impartial reviewers now consider the video inconclusive. With every day, month, and year of searching that fails to produce any other verifiable evidence, the bird's presence becomes less likely.

All the skepticism of Ivory-billed Woodpecker reports could be reversed by a clear photograph tomorrow, in the same way that scientific skepticism over ESP could be reversed by one reproducible experiment. The steady decline in confidence about the Ivory-billed Woodpecker is largely because an intensive research effort over the last three years has failed to produce any proof. In fact what discoveries have emerged from those three years of research (on sounds, flap rates, etc.) have only weakened the original case.

Thomas Gilovich (1991, writing about ESP research) suggests that we can gain perspective by reframing the question we ask. There is a tendency to ask simply: "What evidence supports the claimed rediscovery?" This naturally causes us to emphasize only the supportive elements of the evidence. Instead we can ask: "If Ivory-billeds survived, and an intensive research effort was designed to document their presence, what would we expect to discover in three years of field work?" This question directs us to consider the negative data - the absence of confirmation - along with the positive points. As of October 2007 there are a few reported brief sightings but no photograph (not even a prolonged view). There are tantalizing faint snippets of audio recordings but not a single recording of a clear series of Ivory-billed sounds. There are suspicious excavations and bill-markings on trees, but automated cameras have repeatedly revealed only common woodpecker species at these sites. I'm sure everyone expected more, and is disappointed by the few fragmentary bits of ambiguous data that have actually emerged from all of this effort.

And the formal search efforts of the last three years are dwarfed by the combined observations of millions of naturalists and birders across the southeast over many decades. For over sixty years birders have been fascinated by the Ivory-billed Woodpecker. They have searched promising habitat and followed up any plausible report with genuine excitement and hope, and with a total absence of definitive results. The modern style of birding (chasing rare birds) relies on the fact that a bird - once found - can be found again. Birders avidly check out all kinds of rumors, share directions to the locations of rare birds, and develop bird-finding skills to the point where even the most elusive species can be found and refound (a single Yellow Rail in a marsh in Massachusetts, for example). If the Ivory-billed Woodpecker still existed, the odds that it could consistently elude this army of skilled searchers is vanishingly small. There are still plenty of discoveries waiting to be made, but the implication that birders have been unmotivated and unobservant, and that a population of giant woodpeckers could remain undetected across several states, is simply not plausible (2).

Sightings as evidence

About 30 sightings have been reported since 2004. Many people now point to these as the most convincing evidence, and misrepresent the skepticism over sight records. All sightings to date have been extremely brief glimpses of birds, most were flying away, and most were viewed by a lone observer without the aid of binoculars. All sightings emphasize a single field mark - the white trailing edge of the wing. Some mention vague and subjective (and inconsistent) impressions of size and shape. Other distinctive field marks (such as the large pale bill) have not been seen. Several of the observers actually admit that they are not certain what they saw.

The psychology of perception is very well-studied (1) and shows that all kinds of observer effects can operate subconsciously to alter perception and cause misinterpretation. This is particularly true when the thing being observed is ambiguous (such as a very brief and incomplete view of a bird flying away). What we perceive under those circumstances is easily influenced by expectations, peer pressure, hope, and many other factors.

As most birders know from personal experience, the excitement and anticipation of searching for any reported rare bird often generates spontaneous "false positive" sightings of the sought-after species. Our perception can be very different from reality, and the expression "I know what I saw" is never strictly true. The heightened excitement of the search could easily cause some observers to misinterpret the white wing pattern on a bird glimpsed flying away.

This is why experienced birders repeatedly emphasize the importance of seeing more than one field mark to double-check an identification, and of seeing a bird long enough to confirm and reconfirm all of the observed features. That is still no guarantee of accurate perception, but even that minimum threshold is not met by any of the reported Ivory-billed Woodpecker sightings.

The skeptical position is not in any way a rejection of the value of sight records in birding. Skeptics include the vast majority of North America's most experienced birders, who all rely on sight records but understand how easy it is to make a mistake. Questioning these sight records does not question the honesty or integrity of the observers, it simply acknowledges the fact that perception can be flawed, and that brief views are easily misinterpreted. All observers are fallible, and errors in bird identification are common. The bottom line is that there is simply no way of knowing what was seen.

Proponents often argue that when skeptics discount the eyewitness reports they are setting unreasonably high standards for the evidence. This is not true, and ignores the fundamental weakness of the evidence to date. The opinions of many skeptics would change based on a single sighting of a bird watched for a substantial period of time (even one minute would do), seen through binoculars, with multiple field marks studied and reconfirmed. Experience with other rare birds, especially resident species, suggests that any valid sighting should very quickly lead to more sightings. A pattern of sightings by independent observers, of birds well-seen and studied (not just flying away), would be convincing to most birders even without photos, at least for a while. But even that confidence would fade if the sightings did not eventually lead to verifiable evidence such as clear photos or video.

This level of evidence - redundant sightings and photos - is not difficult to reach with any other North American bird. Yet the Ivory-billed Woodpecker, supposedly resident in a defined area of wooded habitat and reportedly seen by a few observers, still cannot be found and confirmed by thousands of searchers. The continuing absence of any confirmation has caused many birders to reexamine the reported sightings of Ivory-billeds in that context. Should we put more faith in the few reported glimpses, or the countless thousands of hours of unsuccessful follow-up search efforts?

Proponents argue that the sightings are unquestionable and that the species must have become very silent and secretive since the 1940s, and thus very difficult to find. Skeptics argue that all sightings are inherently questionable, and do not confirm the bird's presence, let alone a change in behavior. Accepting the sightings requires one to ignore mounting negative evidence and to invoke a radical and speculative (and unlikely) hypothesis of behavioral change (3). It now seems far more likely that the few reported sightings involve simple, everyday mistakes in perception, and the reason the bird cannot be confirmed is because it is not there.

The Draft Recovery Plan

The authors of the plan admit that confirmation is lacking, but still insist that the evidence is "convincing" and strong enough to warrant a potential $27.7 million of spending in five years (2006! to 2010) which is nearly 5% of the Endangered Species Program's total budget for those years. Some of the money (about half) would be spent on habitat management, the rest on search efforts and research, but regardless of how it's being spent $27 million of public money is too much for an unconfirmed species and could be more beneficial to other species.

The Draft Plan (p. 3) defends this high level of attention by stating that "the U. S. Fish and Wildlife Service is charged to promote conservation and recovery of this species" [emphasis added]. But the U. S. Fish and Wildlife Service is charged to promote the conservation and recovery of all threatened and endangered species, not just this one. Making the Ivory-billed such a high priority inevitably diverts resources from other species.

If every endangered and threatened species had a multi-million dollar budget the Ivory-billed funding would not raise serious concerns. But proposing $27 million for the Ivory-billed Woodpecker, when nearly 1400 other threatened and endangered species receive an average of only a few thousand dollars each, is shockingly unfair.

The Endangered Species Act specifies that:

"The Secretary, in developing and implementing recovery plans, shall, to the maximum extent practicable - (A) give priority to those endangered species or threatened species, without regard to taxonomic classification, that are most likely to benefit from such plans..."

It doesn't say "most charismatic" or "most popular", or even "rarest", it says "most likely to benefit". The Ivory-billed Woodpecker appears likely to be extinct, and therefore not likely to benefit from a recovery plan. Unless it can be found and studied, there is no evidence that it needs any management, and no way of knowing what actions might be harmful. Based on what is known today, almost any of those 1400 other species are more likely to benefit from the resources allocated to the Ivory-billed.

We need to do more for endangered species and I support major increases in funding for the Endangered Species Program. But spending such a large proportion of the current limited budget on one questionable species is wrong and appears to violate the Endangered Species Act. It diverts resources from many species with real, well-documented needs to a single unconfirmed species in an unknown location. In a finite budget there is no conceivable rationale for giving an unconfirmed species hundreds of times more funding than the average threatened or endangered species.

Disturbingly, the recovery plan dismisses the scientific debate in a few sentences. In fact, the debate has been largely one-sided. Not a single independent review has supported the claimed rediscovery of Ivory-billed Woodpecker. All independent reviews to date have reached the same conclusion: that the video from Arkansas matches a Pileated Woodpecker, and that all other evidence is, at best, inconclusive. My colleagues and I published a careful analysis of the Arkansas video (Sibley et al. 2006) showing that a Pileated Woodpecker could account for all of the observed features. The Draft Plan dismisses our work and doesn't even mention independent published research (e.g. Collinson 2007) that fully supports our conclusions. This selective and biased presentation, and the cursory dismissal of objective science by the draft plan, is extremely troubling.

After three years of fruitless search efforts, with several studies refuting the original claim and not a single independent study supporting it, it is grossly misleading to suggest that the evidence is "convincing" and it is irresponsible to place the hypothetical needs of this species ahead of the known needs of so many others. Relentlessly pushing an expensive, single-species policy without scientific support reflects badly on the entire endangered species program. It invites criticism, fosters dissent, and erodes trust.

Ultimately, there is the simple truth that beliefs and possibilities are not a valid basis for conservation policy. Chasing hopeful stories rather than following sound science sets a very bad precedent and leads down a slippery slope where political manipulation thrives.

This recovery plan should be shelved until a real living Ivory-billed Woodpecker is found and confirmed. After three years of unsuccessful government-funded search efforts, the continuing search can safely be left to the army of highly trained and motivated volunteer birdwatchers and naturalists, and the $27 million should be distributed to those confirmed endangered species that are most likely to benefit.

The big picture

The use of the Ivory-billed Woodpecker's questionable rediscovery as a beacon to guide and promote conservation is fraught with pitfalls. Since 2005 a tremendous amount of work has been done exclusively for this species. Some of that work will benefit other species incidentally, but we will never know what could have been accomplished if those same resources had been put to use in a more inclusive plan. Intangible gains from this episode (such as increased public awareness and engagement) are offset by long-term losses (such as disillusionment and distrust) as it becomes clear that the dream we gambled on is actually not becoming a reality.

The rediscovery of the Ivory-billed Woodpecker was hailed as a bright spot in the often-discouraging environmental news. It is a very alluring and positive story of hope, but its central claim is apparently false and it is promoting a fantasy - that living things are ever so resilient and that we have an opportunity for a sort of environmental salvation, a chance to redeem our past transgressions.

The story that we have a second chance with the Ivory-billed carries the dangerous implication that clear-cutting the southern hardwood forests a century ago was not as devastating as we all thought. It promotes the false hope that in spite of our unsustainable use of resources the Ivory-billed Woodpecker was able to adapt and to survive the total destruction of its habitat. And some will take the next logical step and assume that if we have a second chance to save the Ivory-billed, maybe we can continue to clear-cut and develop land and still expect a second chance to save Spotted Owl, California Gnatcatcher, and others.

Efforts to preserve and restore bottomland hardwood forests in Arkansas are laudable, and we all decry the short-sightedness that allowed the cutting of those forests seventy years ago. But even as we focus on those Arkansas forests and the plight of the Ivory-billed, we continue to demand the cutting of old-growth forests elsewhere. Our unrestrained and unrepentant consumption is still dismantling other ecosystems across the continent today. We have failed to apply the most basic lesson that the Ivory-billed Woodpecker's history should teach us.

We all wish that Ivory-billed Woodpeckers still lived, but unrealistic hopes of the species' survival are not helpful. We need to accept the tragic loss of the Ivory-billed Woodpecker, and move beyond it, in order to understand the consequences of our actions then and now. Only that will give us the clarity and the commitment needed to take on the biggest environmental challenges of the present.


1 - for a detailed review of the psychological aspects and how even scientists can succumb to wishful thinking see Risinger et al., 2002 and Gilovich, 1991.

2 - Skepticism of the Ivory-billed's ability to hide from birders was expressed more eloquently in Rick Blom's commentary in Bird Watcher's Digest which was published in 2003, well before the Arkansas reports.

3 - Among many logical flaws in the supporters' arguments is the logical fallacy known as affirming the consequent. The example from Logical Fallacies:

(1) If Zeus was a real, historical figure, but the Catholic Church covered up his existence, then we wouldn't have any evidence of a historical Zeus today.
(2) We don't have any evidence of a historical Zeus today.
(3) Zeus was a real, historical figure, but the Catholic Church covered up his existence.
This is obviously flawed, but corresponds to what Geoff Hill and others are saying:
(1) If the Ivory-billed Woodpecker survived past the 1940s, but became extremely wary and silent, we wouldn't be able to find solid evidence of it today.
(2) We can't find solid evidence of it today.
(3) The Ivory-billed Woodpecker survives but is extremely wary and silent.

Literature cited:

Blom, E. A. T. 2003. Seeking the Ivory-billed Woodpecker. Bird Watcher's Digest. Sep/Oct

Collinson, J. M. 2007. Video analysis of the escape flight of Pileated Woodpecker Dryocopus pileatus: does the Ivory-billed Woodpecker Campephilus principalis persist in continental North America? BMC Biology 5:8

Gilovich, T. 1991. How We Know What Isn't So: The fallibility of human reason in everyday life. The Free Press: New York. 218pp.

Risinger, D. M. et al. 2002. The Daubert/Kumho Implications of Observer Effects in Forensic Science: Hidden Problems of Expectation and Suggestion. California Law Review. 90:1-56

Sibley, D. A. et al. 2006. Comment on "Ivory-billed Woodpecker (Campephilus principalis) Persists in Continental North America". Science 311:1555