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Results of a test of the Hampton Scale, a proposed thayeri-kumlieni-glaucoides 28-point scale for first-cycle birds

The survey featured 12 gulls from across the thayeri-kumlieni-glaucoides spectrum. There were 13 respondents. Each of them rated each gull using the Hampton Scale, scoring each gull with a point value from zero to 28. Each respondent also put a label on each gull. The choices were 1) glaucoides, 2) glaucoides-kumlieni, 3) kumlieni, 4) kumlieni-thayeri, or 5) thayeri.

There are no uniformly accepted criteria for distinguishing between these forms. The survey results underscore that birders have not reached an informal consensus on the matter either. This chart includes all 156 responses-- all 13 respondents for all 12 gulls. The range of scores and labels attached to them suggest a wide range of interpretation regarding these forms. For example, respondents labeled as thayeri birds that they scored from 17 thru 28. Respondents labeled as kumlieni birds that they scored from 8 thru 22. And respondents labled as glaucoides birds that they scored from 1 thru 11. Obviously there is considerable overlap as to which labels apply to which scores. Birds scoring 8-11 and 17-22 particularly lacked consensus.

My sample size of respondents was too small to do an effective analysis of regional bias, but suffice it to say that birders from California were more inclined to label birds toward the thayeri end of the spectrum, while birders in Europe leaned toward glaucoides.

As can be seen in the results for the individual birds below, the respondents did not use the Hampton Scale consistently-- the scores for each bird ranged rather widely. The average range between the high and low scores was 8.3. This suggests the scale is unwieldy and perhaps not useful. Likewise, respondents were far from reaching consensus on a label. Each bird received 13 votes for a name; only 4 of the 12 gulls received more than 7 votes for the same moniker.


GULL #1
Photographed Jan 20, 2013 in Michigan City, IN by Amar Ayyash.


Survey Results
Average score: 24.3

Votes
0 glaucoides
0 glaucoides-kumlieni
2 kumlieni
1 kumlieni-thayeri
10 thayeri


GULL #2
Photographed Jan 20, 2013 in Michigan City, IN by Amar Ayyash.


Survey Results
Average score: 16.0

Votes
1 glaucoides
0 glaucoides-kumlieni
9 kumlieni
2 kumlieni-thayeri
1 thayeri


GULL #3
Photographed Nov 15, 2012 in Santa Cruz County, CA by Jeff Poklen.


Survey Results
Average score: 19.5

Votes
0 glaucoides
0 glaucoides-kumlieni
7 kumlieni
4 kumlieni-thayeri
2 thayeri


GULL #4
Photographed Feb 16, 2013 in Winthrop Harbor, IL by Amar Ayyash.


Survey Results
Average score: 10.4

Votes
2 glaucoides
4 glaucoides-kumlieni
6 kumlieni
1 kumlieni-thayeri
0 thayeri


GULL #5
Photographed Oct 28, 2013 in Indiana Dunes, IN by Pete Grube.


Survey Results
Average score: 20.6

Votes
0 glaucoides
1 glaucoides-kumlieni
2 kumlieni
6 kumlieni-thayeri
4 thayeri


GULL #6
Photographed Mar 19, 2011 in Rio Del Mar, CA by Jeff Poklen.


Survey Results
Average score: 20.9

Votes
0 glaucoides
1 glaucoides-kumlieni
0 kumlieni
2 kumlieni-thayeri
8 thayeri
2 other (presumably Gl-W x Herring; probably correct)


GULL #7
Photographed Feb 2, 2012 in Fort Baker, CA by Steve Hampton and Mark Forney.


Survey Results
Average score: 5.5

Votes
6 glaucoides
3 glaucoides-kumlieni
4 kumlieni
0 kumlieni-thayeri
0 thayeri


GULL #8
Photographed Dec 31, 2012 in Wethersfield, CT by Keith Mueller.


Survey Results
Average score: 19.5

Votes
0 glaucoides
1 glaucoides-kumlieni
7 kumlieni
0 kumlieni-thayeri
5 thayeri


GULL #9
Photographed Feb 28, 2012 in Gloucester, MA by Keith Mueller.


Survey Results
Average score: 10.2

Votes
2 glaucoides
5 glaucoides-kumlieni
6 kumlieni
0 kumlieni-thayeri
0 thayeri


GULL #10
Photographed Mar 22, 2013 in Windsor, CT by Keith Mueller.


Survey Results
Average score: 11.8

Votes
4 glaucoides
4 glaucoides-kumlieni
4 kumlieni
1 kumlieni-thayeri
0 thayeri


GULL #11
Photographed Feb 20, 2013 in Madison, CT by Keith Mueller.


Survey Results
Average score: 21.6

Votes
0 glaucoides
1 glaucoides-kumlieni
0 kumlieni
2 kumlieni-thayeri
9 thayeri


GULL #12
Photographed Feb 23, 2012 in Gloucester, MA by Keith Mueller.


Survey Results
Average score: 7.9

Votes
7 glaucoides
3 glaucoides-kumlieni
3 kumlieni
0 kumlieni-thayeri
0 thayeri


Send comments to me at stevechampton, at gmail.