Thursday, September 27, 2007

Havel on the environment

An Op-Ed in today's New York Times by Vaclav Havel makes reference to the larger issues of consumption and the environment. He minimizes the debate over climate change, saying that whether it is primarily human-caused or not action is important, and there are other equally serious anthropogenic issues which are simply Nature's response to the species known as humans. In today's euphemistic business jargon "we're getting some push-back" (from Nature). Here's a quote from Mr. Havel:
Either we will achieve an awareness of our place in the living and life-giving organism of our planet, or we will face the threat that our evolutionary journey may be set back thousands or even millions of years. That is why we must see this issue as a challenge to behave responsibly and not as a harbinger of the end of the world.

Saturday, September 22, 2007

Siberian vagrants on the move?

Update 24 Sep 2007: Seen on the 22nd was Gambell's 3rd Siberian Accentor, 4th Dusky Warbler, and 6th Little Bunting of the season; while St Paul, Pribilofs turned up their 2nd Siberian Accentor and first Pechora Pipit of the season. And the big news, adding some weight to my tenuous connection - a Common Rosefinch at Southeast Farallon Island, California - the first ever in North America away from western Alaska.
It's been an above-average fall for Asian birds in Alaska. The tiny "oasis" of Gambell, on Saint Lawrence Island, has been well-watched by Paul Lehman and others for each of the last 10 or so falls, so I think it's safe to say that Gambell has more rare birds this fall and not just better coverage. Of course, there could still be other explanations besides more vagrants coming to Alaska - local weather that concentrates or keeps birds at the point or in some way makes them easier to find, the same observers with more experience getting better at finding and identifying rarities, random chance....

The Pribilofs (Saint Paul Island) have had less consistent coverage, and with more habitat vagrant landbirds can be harder to find there (relying more on chance), but this has been a good season compared to the last several years, especially considering the Brown Hawk-Owl last month.

Sky Lark - up to 6 at Pribilofs
Brown Shrike - 1 at Gambell (about 8 NA records)
Siberian Accentors - 2 at Gambell, 1 at Pribilofs (about 25 NA records)
Red-flanked Bluetail - 1 at Pribilofs
Dusky Warbler - 3 at Gambell (now about 20 NA records)
Willow Warbler - 3 at Gambell (bringing the total to 4 NA records, all from Gambell)
Yellow-browed Warbler - 1 at Pribilofs (now 4 NA records, the other three from Gambell in he last few years)
Olive-backed Pipit - 1 at Pribilofs
Pechora Pipit - 2 at Gambell (about 30? NA records)
Pallas's Bunting - 1 at Gambell (6th NA record)
*Yellow-browed Bunting - 1 at Gambell, first NA record
Little Buntings 4 or 5 at Gambell, 1 at Pribilofs (now about 20 total NA records)
Common Rosefinch - 1 at Gambell (about 20 NA records?)

Most birders have little chance of getting to Gambell in the fall, so these reports seem unreal. But if you like to be optimistic, an unprecedented three Arctic Warblers in southern California last week could start to look like a pattern of Asian vagrants. Unprecedented things seem to happen in California pretty regularly... but the distance from Gambell to southern California is about the same as the distance from Gambell to Michigan.

OK, I admit it is a bit of a stretch to link the CA Arctic Warblers to the Siberian birds at Gambell, but birders all over North America would do well to recall past records of things like Siberian Accentors in the northern Rocky Mountains, Siberian Flycatcher in Bermuda, Brown Shrike in Nova Scotia, Siberian Stonechat in New Brunswick, and Siberian Rubythroat in Ontario.

Get to know your local patch, keep an open mind, and go out there and look. There's no telling what might turn up.

Tuesday, September 18, 2007


Here's a neat tool from American Public Radio - an educational game that calculates your global ecological footprint.

Overconsumption is at the core of virtually all environmental problems, and most of that consumption is stuff that we don't even think about. Especially in the fast-paced world of the US middle class, we do things the way we always have. There isn't time to think about each action individually, and options are limited (e.g. transportation of goods has a big impact, but for many products there is simply no option to buy local). But education and incremental changes will help.

So play the game, get some ideas, and think about how to improve your lifestyle. And for inspiration, check out Malkolm Boothroyd's Bird Year.

Monday, September 17, 2007

Fitting pegs in holes

I've thought more about the "square-peg-in-round-hole" analogy in my previous post, and made a few simple drawings to expand that analogy. In many ways, bird identification is like a matching game. The observed bird (here in black) must be identified by matching it to illustrations in a diagnostic key (the gray shapes here).

This is pretty straightforward, and you should have little trouble matching the shape and size of the black object to the gray shape second-from-left. But what if I change the question, to make it conceptually more like a real-world birding situation in which the observation is not absolute, but just a relative judgment of some of the characteristics of the bird: You've seen a bird (black square) and there are five potential species (gray shapes). Which of the five gray shapes is of sufficient size to "fit" the observed shape? i.e. Which holes could the peg fit into?

This is quite a bit tougher. The square second-from-left still provides the best match, but since we're now looking for anything that fits, the black square would also fit inside the gray circle (center) and looks like it might fit in the hexagon on the far left (it doesn't, but that's very difficult to judge).

Now I'll make it even more like a real-world birding situation and present the peg at an odd angle, which then has to be matched to the gray shapes in the diagnostic key (the field guide).
This is a common field situation: you've only seen part of a bird, or only flying away, and you have to be able to interpret the perspective and the contours to figure out which of the nice profile views in the field guide is the best match. In this example I'm still emphasizing the black square (now foreshortened) as the key feature, so by understanding perspective you should be able to match the peg to the square second-from-left... but it's getting harder.

Now I'll take another step into ambiguity, and make this even more like a real birding scenario. Which of the five gray shapes matches the black and gray shape below?
You've observed a three-dimensional shape, from an odd angle, and now you need to match it to one of five potential confusion species, but you don't know which of the observed features of the shape are really diagnostic.

In this case one observer might say "Look at that thin black vertical end, it matches the center shape". Another might say "But look how long it is, it matches the far right". While another might say "We're seeing it from the wrong angle, it's square, and the length is irrelevant, it matches the second-from-left" and a fourth might say "It also fits the circle on the far left, and I don't see how we can rule that out". All are correct interpretations. The only way to resolve this kind of disagreement would be with more study to figure out which features matter, and which are insignificant.

Going back to my first point - bird identification in the real world is rarely as straightforward as the clear differences between these circles and squares. In bird identification we are usually making subtle and subjective judgments such as tail long or short, bill pink or orange, etc. But even seemingly straightforward features like white wing patches can be ambiguous - either misinterpreted or mistaken, or shown by rare individuals of other species. Identification is often not just a question of finding the first species that matches our observations, but considering all species that could fit.

None of these challenges are particularly difficult to overcome, and there is tremendous satisfaction in sorting out bird identification and being able to name a species confidently. But a critical part of doing that well is keeping an open mind, understanding the limitations and pitfalls of our imperfect perception, and having the strength to say "I'm not sure".

Saturday, September 15, 2007

Ambiguity and bird identification

Last week I had the pleasure of spending four days birding at Barrow, Alaska, working on an eider identification project with the US Fish and Wildlife Service. While there I was able to study hundreds of Greater White-fronted Geese that were grazing on the tundra - surprisingly numerous and surprisingly approachable. I'll write a separate note about variation in the geese - size, bill color (pink to orange), and darkness of plumage all seemed to vary independently - but for today I want to comment on a psychological issue that I noticed while looking for these subtle variations.

A drawing showing a series of ambiguous figures is here:
Image from: Fisher, G. H. 1967. Measuring Ambiguity. American Journal of Psychology. 80:541-557.
This series shows an unambiguous "Old Gypsy woman" in the upper left, which then changes gradually to an unambiguous "Young woman with mirror" in the lower right. All of the intermediate drawings are more or less ambiguous: they could be interpreted either way (especially the ones in the center). Interestingly, starting at the corner allows your brain to "latch onto" one interpretation, and then that interpretation can be held across more than half of the series before it involuntarily switches. Once your perception switches, if you then scan back towards the starting point, some of those images will be perceived in the "new" way before involuntarily switching back.

After scanning many flocks of Greater White-fronted Geese at Barrow looking at bill color, I realized that I could perceive a single flock as mostly orange-billed on one scan, and mostly pink-billed on the next scan. Most of the geese have ambiguous bill colors (pinkish-orange or orangey-pink) and my perception was determined by which color I "latched onto" first. If I looked through the telescope and found an orange-billed bird (or called an ambiguous color "orange"), then scanning the rest of the flock would produce an impression that most or all were orange-billed. If I found an unambiguously pink-billed bird then my perception switched, and birds seen after that would be labeled "pinkish".

I've long been aware that context has a profound influence on perception of these subtle and subjective features, but I have rarely experienced such a clear example of it. Birders often deal with these kinds of subtle judgments - size, shape, wingbeats, color, etc - and the stimuli are often ambiguous. We can jump to a conclusion about bird identification based on very limited information, and the jump can be guided by all kinds of subconscious and unrecognized factors. It's valuable to be aware of these pitfalls, to understand the limits of perception and deduction, and to balance the tendency to jump to conclusions with a more thoughtful and cautious approach. A square peg, if it's small enough, fits very nicely in a round hole.

Wednesday, September 5, 2007

Black Tern and White-winged Tern - leg color

Another note from the comments under Sandwich Tern by Joseph Kennedy on 4 September, this deserves a separate discussion (Thanks, Joseph). He writes:
I have received a note Stu Wilson concerning the black tern pictures posted from the same date. I guess that I should check feet on the rest of my tern pictures. According to Sibley, young black terns should have light colored legs as would adult non-breeding birds. My picture of the young black tern has black legs

As does the bird that has assumed most of its winter plumage

Sibley shows all plumages of white-winged terns and adult black terns as having yellow legs, if this is actually a difference, it would be an easy way to id all of the stray white-winged terns that pass through the UTC. Perhaps this is a carryover from European birds and US birds are different.
In The Sibley Guide I illustrated the adult Black Terns with dark legs, which is accurate, and the juvenile Black Tern with bright orange-red legs, which should be a darker dusky pink color, and sometimes blackish. From photos such as the one above it is clear that even juvenile Black Terns can have very dark legs, and the juveniles that have paler legs (photos in Olsen and Larsson) still show dusky pink legs.

All ages of White-winged Tern (from photos in Olsen and Larsson) show brighter orange-red or orange-pink legs - drabber on juveniles than adults, but usually (always?) brighter than on Black Tern. So this might be worth watching for in standing Black Terns. A bird with bright legs could be a White-winged. According to photos, European Black Terns are similar to American birds in leg color.

In photos I also noticed a longer-legged appearance of White-winged Tern, which is confirmed by measurements in Olsen and Larsson: tarsus averages 16mm for Black Tern vs 19mm for White-winged. This is not diagnostic, and apparent leg length depends a lot on posture, but could be a useful point to watch for on standing birds.

Sandwich Tern - leg color

In an interesting 4 September comment under the Sandwich Tern bill color discussion, Joseph Kennedy presents a photo of a juvenile Royal Tern with partly yellow-orange legs. Compared to one of his photos of juvenile Sandwich with yellow legs, the Royal appears to have brighter leg color. Presumably that is variable, but it would be interesting to compare a larger sample. I remember seeing a small but significant percentage of Royal Terns in fall at Cape May, NJ with partly to mostly yellow-orange legs. And non-black legs might be even more common, and more persistent, on Elegant Terns.

Two upcoming events

On Thursday, 27 Sep 2007, I'll be in New Haven, Connecticut lecturing at Yale's Peabody Museum (where I spent many afternoons as a teenager in the 1970s) as part of their John H. Ostrom program series. Details here (click on September and scroll down)

On 19-21 Oct 2007 I travel to Oklahoma to speak and lead a couple of field trips at the University of Oklahoma Biological Station's Friends weekend (public invited).