TasLe 2.—Values for P comparing adults and immature 
birds within populations and each age group between popula- 
tions, blue and lesser snow geese. 
Cape Fort 
Churchill Severn 
Adults Adults 
vS. vS. 2 Areas 2 Areas 
Immat. Immat. Adults Immat. 
Nave. .20 vo —<201 <.01 
| Sarre oh 35 <01 =a0t 
Cale chal .64 < 01 .03 <.01 
Pee oes 87 65 .06 .03 
Fences .66 a4 aot 02 
Za poe .64 82 .80 42 
Mee. cer 87 95) <01 <01 
Mn eer. .60 58 Od 22 
Cu ke. 78 .63 .88 BF 
Sih ogress 62 coe Se 18 
Al acon 24 ol <01 01 
Bey see .O1 38 <1 01 
of feathers. The latter found that silicon (as SiO,) 
may account for as much as 77 percent of the ash of 
the primary feathers of ring doves (Streptopelia roseo- 
grisea) (presumably captives). We assume that most 
minerals have been bonded to the protein matrix of the 
keratin via free charges on the amino acids rather than 
physical adsorption or exchange on the surface of the 
feather. Possibly some minerals occur as salts of acids. 
Certain elements are known to have a competitive and 
others a reciprocal relationship to organic binding sites; 
others may be substitutive. We suspect, however, that 
binding rates of the various ions at the feather follicle 
(anlage) tend to follow the law of mass action. 
In addition to the several recognized ways that min- 
erals in the diet in amounts greater than body needs are 
excreted—by way of the alimentary canal, kidneys, and 
the salt or nasal glands (Nat only)—uit clearly appears 
that the feather protein is a fourth avenue of excretion 
of excess minerals. The data for the two snow goose 
colonies suggest that wild geese maintain normal physi- 
ological functions under widely varying rates of min- 
eral intake. No firm conclusions can be made at this 
time as to either the limits of the capacity of wild geese 
to utilize feather keratin as a mode of mineral excre- 
tion or the nutritional significance of excretion rates via 
the feather follicle. ‘The actual mode and sequence 
of events responsible for mineral incorporation into the 
feather do not appear to be particularly relevant to the 
initial practical objective of the study, i.e., to be able 
to determine the origin or birthplace of individual birds 
6 
or populations in autumn and winter. This objective 
is particularly significant to management of lesser snow 
and blue goose populations, most of which are indistin- 
guishable morphologically, although the birds breed in 
widely separated colonies. 
More feather elements differ significantly between 
these two populations than is the case for similar com- 
parisons between some other populations we have studied. 
However, the technique is useful if the population in 
question can be differentiated from all others by only 
one element. Obviously a population distinctive in 
two or more elements is more readily identified, and a 
spectrum of 12 elements, theoretically, should permit 
a great number of distinctive mineral “profiles” to be dis- 
tinguished among all populations. However, variability 
within most populations considerably limits the actual 
number of distinctive permutations likely to occur. 
Banding has made enormous contributions to our 
understanding of the distribution and seasonal move- 
ments of birds, but the shortcomings of this technique 
are manifest—chiefly, the fact that bandings in any one 
year are parochial in representation and the application 
of band recovery data often involves tenuous statistical 
assumptions and corrections. It is hoped that the tech- 
nique and findings reported here will open a new era 
of more refined identification and management of 
waterfowl populations (Fig. 2). Although the method 
described involves complex and expensive instrumenta- 
tion, our data for color of the feather ash (Jones and 
Hanson, unpublished) of the various populations of 
lesser snow and blue geese indicate that some are also 
“color coded” to their birthplace or breeding area. To 
identify these it is only necessary to wash the clipped 
vanes of the primary feathers, burn them to ash in a 
muffle furnace, and carefully note the color (Munsell 
or some other notation system) to establish the birthplace. 
Studies of trace minerals occurring in natural popu- 
lations, whether in keratin structures or body structures, 
have considerable potential. For example, the hypoth- 
esis has been advanced that soil calcium is a limiting 
factor in the southward distribution of the ring-necked 
pheasant (Phasianus colchicus) in the United States 
(Leopold 1931:125). Because the amount of a min- 
eral in feathers appears to be an expression of the extent 
to which it occurs in excess of metabolic needs in the 
nutrient chain, feather calcium or its ratio to some other 
element or elements may provide new insight into the 
question of pheasant range limitations. 
Feather analysis may be useful in a wide range of 
nutritional studies because results can be obtained 
without sacrificing the experimental individuals. Prior 
to the present studies, Dr. Harold M. Scott of the Col- 
lege of Agriculture, University of Illinois, and the senior 
author held three groups of Canada geese on experi- 
mental rations that differed in only two respects—in 
methionine content and including a supplement of 
MgSO,—from the diet containing the standard min- 
eral mix used at the College in experimental feeding 
