I lived in Britain for three years in the late 70s when jizz birding was rapidly gaining adherents. In most cases, I thought (and still think, to a large extent) that invoking jizz was a indication that the observer was either too inarticulate or too lazy to say what he or she really meant. It was sort of like distinguishing the yellowlegs by saying that the greater has “a bigger beak.” Bigger than what? In the absence of a lesser yellowlegs to compare it with, the observation lacks persuasiveness. On the other hand, observing that “the bill was slightly longer than the head and slightly upturned” is much more useful statement, and one that few of us would argue with.

On a deeper level, “jizz” is a function of the basic human pattern recognition ability. A great deal of the human brain is highly specialized for this function. We are incomparably better than computers at recognizing patterns. And the more often we encounter the pattern, the better we get at recognizing it. For instance, if I see Bill Whan across the room at a meeting, I recognize him immediately, even if he is dressed differently, turned in a different direction, sitting or standing, wearing a hat or not, etc. I suppose you could say I identify him by his jizz. If I can do it with Bill Whan, is it not equally acceptable to identify birds the same way?

The short answer is “yes.” The long answer is that it depends on how well your pattern recognizer is trained. We can all identify robins in a wide variety of circumstances because our pattern recognizer has such an abundance of experience with robins. If we turn to dowitchers, however, the situation is much different. I have been struggling with dowitchers for 40 years. Last year at the shorebird symposium, someone told me about the “swallowed a grapefruit” tip. The next day at Cedar Point, we found a nice stretch of shallow water that held a bunch of really instructive birds. In particular, there were several small groups of dowitchers of both species, and the “swallowed a grapefruit” effect was very evident; distinctive, even.

However, back home, where we experience dowitchers in onesies and twosies (if at all), the “swallowed a grapefruit” effect is not nearly as easy to use, owing to the lack of comparison. Now, if I were in a situation where I encountered both species of dowitchers daily, I would probably become much more confident in using that comparatively elusive element of the dowitcher morphology.

In my experience, pattern recognition skill often has a fairly short shelf life. I have been to Hawk Mountain several times. Each time, I come away able to distinguish Cooper’s and sharp-shinned hawks at a range of two miles. However, after a fairly short time back home, I find myself as puzzled by accipiters as I ever was. The confidence I had developed in a day of intensive pattern recognition training has faded with time.

And that is what makes my wary of endorsing “birding by impression.” The variation of pattern recognition skills across observers and through time means the assertion of an identification on the basis of an “impression” must be viewed with a certain degree of skepticism unless the observer has a widely accepted reputation for accuracy in such circumstances. For the rest of us, we should be prepared to present a bunch of corroborating details.

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