The following item from the New York Times -
March 9, 2002
Will Fingerprinting Stand Up in Court?
PETER NEUFELD and BARRY SCHECK
- got me thinking about the issue of bird identification.
Basically, the issue is that the validity of fingerprint analysis in the US
justice system has come into question. While finger prints are unique to
individuals, the issue is the way prints are "read and matched".
The question in practice is "how much of a match is required to say that a
particular fingerprint is from a particular person." Apparently, the process
used to match "large, evenly pressured prints taken from suspects at the police
smaller, unevenly pressured prints from crime scenes is ultimately
subjective and bedeviled by inconsistent standards. The French, for
example, require that two fingerprints match at 16 points before they can
be accepted as coming from the same person; the Australians, 12; and the
Swedes, 7. The F.B.I. refuses to state a number at all, relying instead on
case- by-case judgments."
A judge has also noted ""alarmingly high" error rates when fingerprint examiners
took proficiency tests; in 1995 only 44 percent of 156 law enforcement examiners
could correctly identify all five prints in the test, and in a 1998 study the
number improved to only 58 percent."
Perceptive readers will by now see a connection between the fingerprint analysis
and the identification of problematic species [eg waders in non-breeding
First, it is easy to compare a bird "in the hand" with a description in a field
guide. It is another thing to positively ID a partially sighted bird moving
about in the distance through a foggy magnifying instrument in poor light.
Second, how many points of identification do you need for a rare species to get
onto the rare bird sighting list?
Generally, when we observe birds, we take shortcuts - for example, one or two
seconds of a call, or a flash of white to list a pied currawong. Often there is
just one point of identification we look for [eg the yellow patch on the side of
the fact to ID a lewin's honeyeater]. While these single points are good rules
of thumb, we may sometimes get caught out with the assumptions me make.
I would think there is a degree of subjectivity in the judging of rare bird
sightings [as evidenced in some of the recent discussions about rare migrants on
BOz] and it would be interesting to know [if one was a "recording angel] the
frequency of type I and type II errors in the annals of rare bird recordings [ie
false positives and false negatives].
As a partially related aside, as I was lugging the week's shopping home up a
long hill round dusk this evening, I heard the characteristic clucking of one of
the local tawny frogmouths. I looked in the direction of the call, and saw a
bush turkey settling in for the night on a tree branch. A humourous
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