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STATE OF ILLINOIS
DEPARTMENT OF REGISTRATION AND EDUCATION
NATURAL HISTORY SURVEY DIVISION

INFLUENCE OF

LAND USE, CALCIUM, AND WEATHER

ON THE DISTRIBUTION AND ABUNDANCE
OF PHEASANTS IN ILLINOIS

Ronald F. Labisky
James A. Harper
Frederick Greeley

Illinois Natural History Survey
Biological Notes No. 5l

Urbana, Illinois * December, 1964

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INFLUENCE OF LAND USE, CALCIUM, AND WEATHER
ON THE DISTRIBUTION AND ABUNDANCE

OF PHEASANTS IN ILLINOIS

Ronald F. Labisky, James A. Harper, and Frederick Greeley

THE EXOTIC RING-NECKED PHEASANT
(Phasianus colchicus), introduced into Illinois in the
1890’s (Robertson 1958:3), has established thriving self-
maintaining populations in the northeastern third of the
state (Greeley, Labisky, & Mann 1962:6-16). By the
middle 1930’s, pheasants had established a center of
abundance in Livingston and Ford counties of east-cen-
tral Illinois (Fig. 1), a center that has persisted and pros-
pered to the present time. In winters of the late 1950's,
pheasants numbered between 60 and 90 birds per square
mile in portions of east-central Illinois.

Pheasants have never established self-maintaining
populations in the west-central and southern counties of
Illinois (Fig. 2), even though many propagated birds
have been liberated in some of these counties by both
private and public agencies during the past 50 years.
There is much variation in the abundance of pheasants
in different portions of the range occupied by these birds.
The phenomenon of limited distribution and variable
abundance of pheasants is not unique to Illinois but is
common over much of the pheasant range in the mid-
western states. This paper reviews published findings
and presents new data on three factors, land use, calcium,
and weather, all commonly considered as influencing the
distribution and abundance of pheasants in Illinois.

Acknowledgments

Acknowledgments are made to the following person-
nel, present or former, of the Section of Wildlife Re-
search, Illinois Natural History Survey: Thomas G.
Scott, who, as Head of the section at the time of research,
provided administrative and technical supervision; and
William R. Edwards, present Associate Wildlife Special-
ist, Jack A. Ellis and William L. Anderson, present Re-
search Associates, and Stuart H. Mann, former Research
Assistant, all of whom offered advice during preparation
of the manuscript. James S. Ayars, Technical Editor,
Illinois Natural History Survey, edited the manuscript.

Horace W. Norton, Professor of Statistical Design
and Analysis, Department of Animal Science, University
of Illinois, and a consultant to the Natural History Sur-

This paper is printed by authority of the State of Illinois,
IRS Ch. 127, Par. 58.12. It is a contribution of Illinois Federal
Aid Project No. 66-R, the Illinois Department of Conservation,
the United States Bureau of Sports Fisheries and Wildlife, and
the Illinois Natural History Survey, cooperating.

Ronald F. Labisky is Associate Wildlife Specialist, Illinois
Natural History Survey, Urbana. James A. Harper and Fred-
erick Greeley were formerly employed as Research Associates
by the Illinois Department of Conservation under terms of the
Federal Aid in Wildlife Restoration Act and assigned to the
Illinois Natural History Survey for administrative and technical
supervision. Greeley is now Associate Professor of Wildlife
Management, University of Massachusetts, Amherst; Harper

is now Wildlife Biologist, Oregon State Game Commission,
Corvallis.

vey, gave advice on statistical computations and interpre-
tations in the section “Pheasants and Land Use.”
Photographs for the cover and Fig. 1 were taken by
Wilmer D. Zehr, present photographer of the Illinois Nat-
ural History Survey; those for Fig. 5 and 6 were taken by
William E. Clark, former photographer of the Survey.

Pheasants and Land Use

Although the distribution and abundance of pheasants
are the result of a web of interrelated factors, the relation-
ship between pheasants and land use merits primary
consideration because land use is an important deter-
minant of habitat. In an evaluation of the components
of pheasant habitat in Illinois, land use is of special im-
portance because of pronounced differences in agricul-
tural practices within the pheasant range. Topography
and soil characteristics exert an appreciable effect on
land use, but they will not be discussed specifically in
this report.

In the midwestern states, pheasants appear to be
tolerant of considerable variation in the proportion of
the land cultivated (land in agricultural crops). Kimball,
Kozicky, & Nelson (1956:213) reported that between
50 and 75 per cent of the land area within the best
pheasant range of the Plains and Prairie States (the
Dakotas, Nebraska, Minnesota, and Iowa) was cultivated.
Leedy & Hicks (1945:101) suggested that land cultivated
to the extent of 75 to 95 per cent provided one of the
conditions for superior pheasant range in Ohio. Shick
(1952:18) reported that in 1941 about 70 per cent of
the land on the Prairie Farm in Michigan, a highly pro-
ductive pheasant area, was cultivated. Investigators in
Minnesota (Erickson et al. 1951:40-41) reported “heavy
production of corn and grain” as one characteristic of
good pheasant habitat. Robertson (1958:13) stated
that over most of the range of the pheasant in Illinois
as much as 95 per cent of the land area might be classed
as agricultural.

In Illinois, the numbers of pheasants counted along
roadsides by rural mail carriers during periods of 5
consecutive days in February, April, and August of 1957
and January, April, and August of 1958 (Greeley et al.
1962:4) were used to classify the 102 counties of the
state with respect to the relative abundance of pheasants.
Twenty-eight of the southern counties of Illinois in which
no pheasants were observed during the February, 1957,
census (Greeley et al. 1962, Fig. 2) were classed as non-
pheasant range. These counties, the last 28 in Table 1,
were not included in subsequent censuses; in all analyses,
they were considered as nonpheasant habitat.

As an aid to biological interpretations of the relation-
ships between land use and pheasant abundance in Illi-
nois, the data were analyzed for statistical significance
on an IBM 7090 digital computer; the mathematics in-
volved a multiple regression analysis by the least squares
method.

Test statistics included 10 independent variables in-
volving land use (Table 1) and three dependent variables
involving pheasant abundance. Indices of abundance
were based on the mean number of pheasants observed
by rural mail carriers per 100 miles of driving in Illinois
counties during six counts in 1957 and 1958 (Table 1).

Tasie 1.—Abundance of pheasants in relation to land-use practices in Illinois counties. Abundance for each county within the
pheasant range was determined by calculating the mean number of pheasants reported by rural mail carriers per 100 miles of
driving during six 5-day census periods, 1957 and 1958. All counties of the state were included in the first census; 28 southern
counties (75—102 below) in which no pheasants were reported were not included in later cenususes.

eo of Per Cent of Per Cent of Per Cent of Cropland
Pheasants Per County in Farms? in and Pastureland** in
Abundance 100 Miles Crop- Wood- Cash Live- Row Small Pas- Idle
Ranking County of Driving land* landt Grain Dairy — stock Crops Grain Hay ture’ Land
1 Livingston 75.2 88 1 74 2 7 56 26 5 12 1
2 Ford 55.2 88 0 71 1 10 55 24 5 13 1
3 Marshall 22.5 70 11 46 2 30 46 22 6 23 1
4 McLean 22.2 85 2 58 3 18 57 22 5 15 1
5 Iroquois 21.5 85 2 67 2 10 60 21 5 12 1
6 De Kalb 20.8 88 1 13 14 54 47 24 11 13 1
7 La Salle 19.6 78 4 58 3 20 50 24 7 17 1
8 Kendall 19.1 84 4 31 6 36 49 28 9 13 1
9 Kankakee 16.5 78 4 64 4 7 59 22 5 12 1
10 Woodford 16.2 75 9 54 4 21 47 24 6 21 1
11 Champaign 5).il 87 1 77 2 7 65 21 cs 10 1
12 Grundy 13.8 79 4 76 2 7 54 23 5 16 1
13 McHenry 13.4 68 4 5 65 9 31 18 19 28 1
14 Stephenson 11.5 76 4 4 42 33 28 22 17 31 1
15 Lee 10.9 80 2 36 7 28 46 24 9 18 1
16 Vermilion 3 78 5 49 3 16 60 18 3 15 1
17 Putnam 8.0 64 17 41 4 38 41 20 8 29 1
18 Kane 6.4 76 3 10 36 26 41 24 14 18 1
19 Boone 5.6 81 3 6 66 16 32 21 13 24 1
20 Logan 5.5 85 3 76 1 12 56 24 “) 13 2
21 Will oy) 69 4 44 14 10 49 26 8 i4 1
22 Du Page O72, 51 5 12 18 16 41 26 12 17 2
23 Piatt 4.9 88 2 74 1 8 63 21 3 11 1
24 Douglas 4.5 85 2 69 3 9 67 20 2 10 1
25 Carroll 3.8 65 7 2 14 68 28 19 15 35 1
26 Stark 3.8 81 3 27 1 58 46 21 9 22 1
27 Menard 3.5 75 8 49 2 25 51 20 a 22 1
28 ‘Tazewell 3.0 73 9 49 6 16 48 21 6 19 2
29 Lake 2.9 44 7 6 32 10 27 23 19 24 :
30 Cook Ee) 28 5 10 17 9 34 22 14 13 3
31 Edgar 2.9 75 6 48 3 27 57 18 3 20 1
32 De Witt 2.8 79 4 60 2 17 59 17 4 18 1
33 Ogle 2.7 76 6 12 16 43 34 24 12 23 2
34 Winnebago Peal 66 7 7 29 22 32 22 15 27 1
35 Jo Daviess 2b 49 15 l 21 58 17 13 16 53 1
36 Henry 2.1 78 3 12 2 67 45 21 10 23 1
37 Bureau 1.8 76 6 22 3 54 45 21 9 23 1
38 Effingham a3) 64 15 23 16 11 44 17 7 28 3
39 Mason 1.4 69 13 73 l 10 45 26 4 13 5
40 Coles 0.9 76 U 45 2 25 57 16 4 20 2
41 Whiteside 0.8 77 + 18 14 43 45 22 9 23 1
42 Moultrie 0.8 82 a 57 3 14 60 19 4 16 1
43 Jasper 0.8 68 11 25 2 20 51 14 8 23 4
44 McDonough 0.6 68 11 26 2 48 44 21 4 29 1
45 Henderson 0.5 62 14 30 I 55 43 17 6 29 Ss
46 Macon 0.5 82 3 56 2 9 61 21 4 13 1
47 Adams 0.4 58 17 18 7 45 30 22 7 38 3
48 Warren 0.3 71 7 17 1 68 45 19 7 28 1
49 Cass 0.2 54 19 57 0 26 47 18 4 24 3
50 Sangamon 0.2 73 4 43 4 24 54 21 4 19 2

Taste 1.—(Continued)

e
een of Per Cent of Per Cent of Per Cent of Cropland
Pheasants Per County in Farms? in and Pastureland** in

Abundance 100 Miles Crop- Wood- Cash Live- Row Small Pas- Idle

Ranking County of Driving land* landt Grain Dairy — stock Crops Grain Hay ture Land
51 Schuyler 0.2 49 25 29 2 41 32 18 5 43 1
52 Peoria 0.2 7) 13 26 5 36 38 20 8 32 |
53 Christian 0.2 79 3 60 2 15 56 24 4 15 1
54 Cumberland 0.2 68 14 29 2 23 51 12 5 28 3
55 Shelby 0.2 70 11 38 8 18 50 17 Fy 26 2
56 Rock Island 0.2 57 13 8 6 54 36 16 9 36 2
57 Hancock 0.1 63 9 26 2 44 38 21 5 34 1
58 Fayette 0.1 58 18 27 9 15 42 13 7 32 5
59 Bond 0.1 60 15 19 21 12 39 18 7 32 4
60 Montgomery 0.1 64 10 33 11 15 44 21 6 28 1
61 Knox 0.1 61 9 14 2 63 40 18 8 33 1
62 Greene 0.1 58 16 26 5 42 41 15 5 36 3
63 Mercer 0.1 67 8 10 1 74 39 16 9 34 2
64 Clay 0.1 64 15 23 2 14 43 11 10 28 7
65 Morgan 0.1 67 8 39 3 35 46 20 5 28 1
66 Clark 0.0+ 65 18 23 4 21 45 15 5 29 5
67 Pike 0.0+ 58 18 18 2 54 32 14 5 40 8
68 Macoupin 0.0+ 60 17 33 7 24 43 16 6 33 2
69 Scott 0.0+ 66 13 35 1 43 44 19 4 29 3
70 Richland 0.0+ 67 13 14 5 15 oi 12 13 26 11
71 Fulton 0.0+ Sil 17 18 2 52 35 17 5 40 2
ie Crawford 0.0+ 63 14 21 6 22 41 12 7 29 10
73 Jersey 0.0+ 52 28 28 9 24 37 18 6 33 5
74 Brown 0.0 47 Pil 14 2 67 28 15 4 49 a
75 White 0.0 69 9 33 2 32 45 13 3 21 16
76 Wabash 0.0 66 10 35 1 26 46 20 6 18 7
77 Wayne 0.0 63 16 18 2 21 40 7 9 31 12
78 Washington 0.0 65 17 36 15 + 26 38 5 20 7
79 Clinton 0.0 64 19 27 21 6 37 33 7 19 4
80 Monroe 0.0 63 24 33 1 11 28 37 5 15 13
81 Lawrence 0.0 61 14 26 5 21 45 15 6 23 10
82 Edwards 0.0 71 14 19 2 33 39 15 7 27 10
83 Madison 0.0 59 12 20 18 12 36 27 8 24 4
84 St. Clair 0.0 58 13 35 8 13 35 35 6 15 7
85 Randolph 0.0 58 22 19 14 22 28 26 U 25 13
86 Perry 0.0 54 22 11 10 14 26 19 6 28 17
87 Pulaski 0.0 56 26 12 4 21 41 6 9 29 10
88 Massac 0.0 51 28 15 3 32 37 5 9 40 7
89 Saline 0.0 55 18 15 4 17 39 10 7 31 11
90 Gallatin 0.0 57 26 28 2 30 43 8 4 26 13
91 Franklin 0.0 53 22 11 5 10 29 16 6 30 17
92 Hamilton 0.0 58 19 14 2 23 38 10 6 29 15
93 Jefferson 0.0 57 17 14 3 19 35 13 7 31 13
94 Marion 0.0 55 17 21 1 18 36 14 7 32 8
95 Calhoun 0.0 41 43 12 0 48 23 9 5 46 10
96 Jackson 0.0 43 32 16 10 18 31 a, 7 33 13
97 Union 0.0 42 38 1] 9 21 26 6 12 36 13
98 Alexander 0.0 40 47 32 0 14 50 4 8 22 11
99 Johnson 0.0 48 36 2 4 36 18 2 13 54 10
100 Pope 0.0 31 41 12 3 28 23 3 11 48 12
101 Hardin 0.0 42 38 5 1 32 18 0 10 58 13
102 Williamson 0.0 40 21 7 6 16 27 5 9 40 iW)
Mean 4.5 65 13 30 8 27 42 18 7. 26 5

* Calculated from data published by the United States Bureau of the Census (1952:40-47); data are for 1950.

+ From King & Winters (1952:21-22); wooded areas in narrow strips and areas of less than 1 acre are not included in
the statistics, which are for 1948.

t Calculated from data published by Ross & Case (1956:35, 40, 42, 45, 49, 52, 55, 58, 60). A farm classified as one of these
types derived 50 per cent or more of its total income from sales of the product from which it derived its name (Ross & Case
1956:33). Only cash-grain, livestock, and dairy farms are included here because they are the dominant specialized types in
and around the major portion of the Illinois range occupied by pheasants (Fig. 3). Most of the farms not included in the
three types are classified as general farms.

** From Ross & Case (1956:38, 40, 43, 47, 50, 53, 56, 58, 60). The classification pasture includes woodland that was grazed
by livestock. In all counties, a small percentage (in some counties less than one-half of 1 per cent) of cropland was planted
to crops not included in the five types specified below; the approximate percentage for the “other crops” can be found by
subtracting the percentage for these five types from 100 per cent,

Taste 2.—Variance ratios obtained from analysis of variance tests between (i) three different statistical transformations of
pheasant abundance as expressed in pheasants observed by rural mail carriers per 100 miles of driving (dependent variables)
and (ii) 10 different land-use statistics (independent variables) for the 102 counties of Illinois.

Degrees
Pheasants per of
100 Miles Freedom
of Driving Source (d.f.)
Mean number Regression 10
Deviation 91
101
Square root of
mean number Regression 10
Deviation 91
101
Log transformation of Regression 10
mean number? Deviation 91
101

Va ia nce
Sum of Squares Mean Square Ratio (F)
5,370.503 537.050 7.20%
6,791.512 74.632 |
11,162.015 110.515
189.394 18.939 14.60*
118.073 1.298 3
307.468 3.044
17.017 1.702 19.91*
7.783 0.086
24.800 0.246

* Significant at the 0.01 level of probability.

+ Logie of 1 plus the mean number of pheasants observed by rural mail carriers per 100 miles of driving.

The three dependent variables were (i) the mean num-
ber of pheasants per 100 miles, (ii) the square root of
the mean number of pheasants per 100 miles, and (iii)
the log,, of 1 plus the mean number of pheasants per
100 miles of driving. The log transformation of the
mean number of pheasants (iii) proved to be better than
the two other dependent variables because with it more
of the variations of data could be explained by the 10
independent variables (Table 2) : it was used as the de-
pendent variable in all subsequent statistical analyses.

The total correlation (positive or negative) of in-
dividual independent variables with the log transforma-
tion of pheasant abundance was found to be statistically
significant at the 0.01 level (with 101 degrees of freedom)
for 7 of the 10 independent variables (Table 3). This
finding suggested that variations in 7 of the 10 land-use
factors tested statistically were associated with variations
in the abundance of pheasants in Illinois.

The significant correlation between the abundance of
pheasants and the percentage of cropland (r= 0.629,
Table 3) demonstrated that pheasants were most abun-
dant in counties having a high proportion of cultivated
land (Table 1). In 9 of the 10 counties in which pheas-
ants were most abundant, at least 75 per cent of the
land was in crops, whereas in 20 of 28 southern counties
from which pheasants were absent less than 60 per cent
of the land was in crops.

The amount of woodland in Illinois counties varied
inversely with the relative amount of cropland and the
abundance of pheasants (Table 1 and Fig. 3). A highly
significant negative correlation (r — — 0.612) was ob-
tained between pheasant abundance and the relative
amount of woodland in the counties (Table 3). The best
pheasant counties of Illinois had little or no woodland
(Fig. 2 and 3).

The abundance of pheasants was significantly cor-
related (r —0.476) with the relative number of cash-
grain farms among all farms in the counties (Table 3).

Cash-grain farms comprised 74 and 71 per cent of all
farms in Livingston and Ford counties, the counties in
which pheasants were most abundant, and more than
50 per cent of all farms in many of the other counties
in which pheasants were numerous (Table 1). The
abundance of pheasants was less associated with the rela-
tive number of dairy and livestock farms in the counties
than with the relative number of cash-grain farms
(Tables 1 and 3).

In most of the counties within the range occupied
by pheasants in Illinois, a high proportion of cropland
(referred to as cropland and pastureland in Table 1) was
devoted to row crops. mainly corn (Zea mays) and soy-
beans (Glycine max). The proportion of cropland

TaBie 3.—Test of significance by analysis of total correlation
for each of 10 independent variables with the log transforma-
tion of pheasant abundance* in the 102 counties of Illinois.

Correlation
Coeffiecient (r)

Level of Signifi-

Independent Variable cance (101 df.)

Per cent of county in

Cropland 0.629 0.01

Woodland —0.612 0.01
Per cent of farms in

Cash grain 0.476 0.01

Dairy 0.217 0.05

Livestock -0.177 NS?
Per cent of cropland in

Row crops 0.444 0.01

Small grain 0.414 0.01

Hay 0.125 NS?

Pasture (including

grazed woodland) 0.544 0.01
Idle land 0.549 0.01

* Loge of 1 plus the mean number of pheasants observed
by rural mail carriers per 100 miles of driving.
+ Not significant at 0.05 level of probability.

planted to corn and soybeans was greatest in counties
in which pheasants were most abundant; the correlation
of pheasant populations with the acreage of row crops
(r = 0.444) was highly significant (Table 3). A high
proportion of the land planted to row crops was charac-
teristic of counties in which cash-grain farms predomi-
nated. A lower proportion of the land in row crops was
found in counties in which dairy and livestock farming
necessitated greater acreages of tame hay and pasture.
Pheasants were most abundant in counties in which at
least 45 per cent of the cropland was planted to row
crops (Table 1).

The proportion of cropland planted to small grains,
mainly oats (Avena sativa) and wheat (Triticum aesti-
vum), was also significantly correlated (r = 0.414) with
the abundance of pheasants (Table 3). Small grains
occupied 20 to 25 per cent of the cropland in most
counties where pheasants were abundant. Small grains,
particularly oats, were important in that they usually

BOONE, MCHENRY RK
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CHRISTIAN
MONTGOMERY

CUMBERLAND

JASPER
CRAWFORD
RICHLAND] ce

SHELBY
FAYETTE

EFFINGHAM,

WAYNE

JEFFERSON

WASHINGTON

PHEASANTS PER

100 MILES ———
E33] - 10.1-50.0

(.4-1.1-10.0

[_]-1.0-0.0

Fic. 2.—Distribution and abundance of pheasants in IIli-
nois as mapped from data obtained from six censuses by
rural mail carriers, 1957 and 1958 (modified from maps by
Greeley et al. 1962:6—12). Twenty-eight counties in which no
pheasants were observed during the February, 1957, census
were classed as nonpheasant range (south of heavy line).

MIXED
LIVESTOCK 22

DU PAGE

FANKAKEE

LIVESTOCK
AND GRAIN

LIVINGSTO!

ao,
OE WITT /

GENERAL
FARMING A

GENERAL
GENERAL 5 FARMING
FARMING s\n ol CRAWFORD §

AND DAIRY

GRAIN AND
LIVESTOCK

PER GENT OF LAND AREA
IN FOREST OR WOODLAND

=== ]50-9
10-19 F

: GENERAL FARMING
OM 20-29 AA AND FRUIT
Gitd 930-39 :
GEER «40 AND OVER

Fic. 3.—Rank of Illinois counties in pheasant abundance
(1—74 in Table 1) in relation to farming-type areas (after
Ross & Case 1956:32) and forestation (after King & Winters
1952:22). Counties are ranked in order of pheasant abundance
as determined from censuses by rural mail carriers, 1957 and
1958. No rank is assigned to 28 southern counties.

provided a nurse crop for grass-and-legume seedings,
which produced hay and pasture crops in the subsequent
year or years. Small grains were important also in that
the stubble provided top-quality roosting habitat—an
often overlooked requirement—for pheasants during late
summer, fall, winter, and early spring.

Pheasants were most abundant in counties with pro-
portionately small acreages of hay and pasture, both of
which consisted mainly of tame grasses and legumes. Yet
studies of the nesting ecology of pheasants in the cash-
grain area of east-central Illinois during a 5-year period,
1957—1961, showed that between 50 and 75 per cent
of the annual hatch of pheasant chicks was produced
in tame hay. Fewer acres of hay were reported in the
cash-grain area than in other farming-type areas; the
forage crops, hay and pasture, were not utilized by
farmers so intensively in the cash-grain area as in the
dairy and livestock areas. ‘The counties of Livingston
and Ford, which supported the greatest abundance of

pheasants in the state, had 5 per cent of the cropland in
hay and 12.5 per cent in pasture. As might be expected,
pheasant abundance for all counties combined was nega-
tively correlated (r = — 0.544) with the amount of crop-
land in pasture (Table 3). Surprisingly, however, there
was no significant correlation between pheasant abun-
dance and the amount of cropland planted to tame hay.

Idle land did not constitute an important habitat
for pheasants in Illinois, as indicated by a significant
negative correlation (r—=—0.549) between the abundance
of pheasants and the relative amount of idle land per
county (Table 3).

When the independent variables were treated in an
analysis of multiple regression, interactions among the
individual variables were clearly defined. This analysis

Taste 4.—Test of significance by analysis of multiple regres-
sion for the 10 independent variables of land use with the log
transformation of pheasant abundance* in the 102 counties
of Illinois.

Regression
Coefficient (6)

Level of Signifi-

Independent Variable cance (101 d_f.)

Per cent of county in

Cropland 0.014 0.01

Woodland —0.003 NSt
Per cent of farms in

Cash grain 0.019 0.01

Dairy —0.002 NS?

Livestock 0.003 NSt
Per cent of cropland in

Row crops —0.036 NSt

Small grain —0.034 NS

Hay 0.051 0.05

Pasture (includes

grazed woodland) —0.032 NSt
Idle land —0.039 NSt

* Logi of 1 plus the mean number of pheasants observed
by rural mail carriers per 100 miles of driving.
+ Not significant at 0.05 level of probability.

Taste 5.—Variance ratios obtained from analysis of variance
tests between the groupings of significant and nonsignificant
independent land-use variables (Table 4) and the log trans-
formation of pheasant abundance.*

Degrees of Variance
Freedom Sum of Mean Ratio
Source (d.f.) Squares Square (F)
Regression
Cropland, cash-grain
farms, and hay 3 16.323 5.441 63.277
Other independent
variables 7 0.694 0.099 1.15¢
Deviation 91 7.783 0.086
101 24.800 0.246

*Logio of 1 plus the mean number of pheasants observed
by rural mail carriers per 100 miles of driving.
} Significant at 0.01 level of probability.
ft Not significant at 0.05 level of probability.

indicated that a combination of three factors of land use,
(1) per cent of county in cropland, (ii) per cent of cash-
grain farms among all farms in county, and (iii) per
cent of cropland in hay, when tested against the other
land-use statistics, exerted the most important influence
on the distribution and abundance of pheasants in IIli-
nois (Table 4). The degree of importance of these three
factors or independent variables was further exemplified
by a comparison (Table 5) of the variance ratio of these
three variables combined (F = 63.27) with the variance
ratio of the seven other independent variables combined
(F = 1.15).

In summary, the following factors of land use were
found to be characteristic of many of the counties in
Illinois where pheasants were most abundant: (i) a
high proportion of the land area in cultivated crops and
a low proportion in woodland, (ii) a high proportion of
the farms classified as cash-grain farms and a lower pro-
portion as dairy farms and livestock farms, and (iii)
about 50 per cent of the cropland in row crops (corn
and soybeans), about 5 per cent in hay, and about 15
per cent in pasture. A multiple regression analysis in-
dicated that a combination of three land-use variables,
(i) the relative amount of land in cultivated crops, (ii)
the relative number of cash-grain farms among all farms,
and (ili) the relative amount of cropland in hay, when
tested against all other land-use characteristics, exerted
the greatest influence on the distribution and abundance
of pheasants in the state.

Pheasants and Calcium

A supposed deficiency of calcium in soils and glacial
drift has long been regarded as a factor limiting the
southward extension of the range of the pheasant in the
North Central States, as well as a factor limiting the
abundance of this bird in other parts of the United States.
Leopold (1931:125-126) noted that the successful es-
tablishment of pheasants in the North Central States ap-
peared to be confined within the exterior boundary of
the Wisconsinan glacier — that is, confined to soils of
recent glacial origin. He advanced the hypothesis that
some plant growing on these glacial soils or some sub-
stance, such as kind of lime or gravel, present in these
soils was necessary for the welfare and breeding vigor
of exotic game birds. Dale (1954:320) noted that there
seemed to be a correlation between the availability of
calcium and the abundance of pheasants in the major
pheasant centers of the eastern half of the United States.
McCann (1961:189-190) contended that grit high in
calcium and low in magnesium was of paramount im-
portance to wild pheasants in Minnesota. The impor-
tance of calcium in reproduction, growth, and other
physiological processes of birds is so great that, obviously,
a critical shortage or the absence of this mineral could
prevent the establishment of self-maintaining pheasant
populations.

Although calcium is an essential element for many
physiological processes of birds, more emphasis in re-
search has been placed on the role that this element

plays in reproduction than in any other process. To
obtain a picture of the importance of calcium in repro-
duction of the pheasant, we must draw heavily from
literature on the domestic chicken (Gallus domesticus)
and, also, we must assume that the physiological proces-
ses of the pheasant approximately parallel those of the
chicken.

About 98.2 per cent (2.2 grams) of the shell of the
ege laid by the domestic hen consists of calcium; ap-
proximately 6.0 per cent of the contents of the egg is
calcium (Romanoff & Romanoff 1949:353-354). This
calcium comes either directly from the daily diet of the
hen or from her body reserves of calcium; the body re-
serves are, of course, dependent upon the calcium intake.
Prior to the onset of laying, the hen will store a reserve
of calcium along the shaft cavities of the long or medul-
lary bones; this deposition of reserve calcium is under
the control of estrogens (Héhn 1961:109; Marshall
1961:196).

The circulatory system transports calcium from the
viscera or the bones, or both, to the oviduct, where the
calcium is deposited on and in the egg as calcium car-
bonate and other calcium salts. The shell gland of the
oviduct is about 20 per cent efficient in removing calcium
from the plasma in the blood stream during early as well
as late stages of shell formation (Winget, Smith, &
Hoover 1958:1327).

Common (1943:218-219) demonstrated that the
average daily retention of calcium from the food of
laying hens was about 50 per cent of the intake if the
daily intake averaged 1-3.5 g, but that on days of shell
secretion the retention of calcium might rise to about 70
per cent. He found that, whenever the average daily
intake was as low as about 2 g calcium, mobilization of
the reserves of skeletal calcium was practically certain;
he estimated that a daily intake of 4 g calcium might
suffice to protect the skeletal reserves of hens on sus-
tained schedules of egg laying. Tyler (1940:211) re-
ported that in the laying hen no more than about 1 g
calcium can be withdrawn from the bones on any day
the hen lays an egg and no more than about 1 g cal-
cium can be deposited in her bones on any day she does
not lay an egg. Approximately 25 per cent of the body
reserves of calcium (about 98 per cent of which is
found in the skeleton) at the commencement of laying
can be used in egg formation (Common 1938:354—357) ;
under favorable conditions, prelaying storage of calcium
in the body of the hen is sufficient for the laying of
about six eggs. That prelaying storage of calcium suffi-
cient for about six eggs takes place in pheasants, also, is
indicated by the findings of Harper (1964:267), who
reported that the amount of calcium found in the grit
from gizzards of wild pheasant hens increased from less
than 1 per cent to more than 2 per cent after the hens
had laid six or seven eggs and remained relatively stable
until the second or third day of incubation; midway
through the 23-day incubation period, the amount of
calcium found in the gizzard grit of wild hens decreased
to near zero.

Phosphorus as well as calcium is mobilized during
ege formation in some birds (Marshall 1961:197) and
is closely associated with the calcium complex. If a
diet is deficient in calcium during the period of egg lay-
ing, phosphorus is excreted more rapidly than normally
(Common 1936:96) and may even be drawn from the
body reserves (Romanoff & Romanoff 1949:240). As
with reserves of calcium, reserves of phosphorus must
be replenished through the diet.

Although a deficiency of calcium has never been
detected in populations of pheasants in the wild, dietary
levels of calcium below which penned pheasants cannot
carry on normal reproduction have been reported by
several investigators. In an experiment with penned
pheasants, Dale & DeWitt (1958:293) found that dur-
ing the reproductive season 600 mg of calcium per kg
of body weight per day (calculated by us to be equiv-
alent to 1.2 per cent of the diet) and 385 mg of phos-
phorus per kg of body weight per day were necessary to
insure satisfactory production of pheasant eggs and young
from hens that had received adequate calcium and
phosphorus during the previous winter. In another ex-
periment with penned pheasants, Greeley (1962:188—
190) found that a diet containing 1.09 per cent, or less,
calcium resulted in reduced (i) egg production, (11) egg-
shell thickness, (iii) weight of eggs, and (iv) ash content
and weight of tibiae and femora of laying pheasant hens;
a diet containing 2.01 per cent calcium seemed adequate
for normal reproductive activities of penned pheasant
hens.

The level of calcium required by wild pheasant hens
to complete successfully the annual reproductive cycle
has not been measured directly. Without doubt, some
of the calcium required by wild hens, as well as by
penned birds, must come from the daily diet and some
from the body reserves. Throughout much of the pheas-
ant range in the United States, cereal grains, which are
notably low in calcium, comprise a large percentage of
the diet of the pheasant. Trautman (1952:25-26) in
South Dakota and Fried (1940:30) in Minnesota re-
ported that grains comprised 81.7 and 81.3 per cent of
the annual diet of pheasants in their respective states.
Dalke (1937:204) reported that grains constituted 74.0
per cent of the annual diet of pheasants he studied in
southern Michigan.

Dale (1954:318) estimated that calcium made up
approximately 0.23 per cent of the annual diet, includ-
ing all food items, of the pheasants studied by Traut-
man in South Dakota and by Dalke in Michigan. Harper
& Labisky (1964:726) found that, in the established
pheasant range in Illinois, calcium comprised 0.21 per
cent of the food items from the crops of hens collected
during the nesting seasons (May and June) of 1961
and 1962. If the calcium requirements of wild pheasants
are similar to those of penned pheasants, then obviously
the food items consumed by wild pheasants do not supply
sufficient calcium to allow normal reproduction, and a
supplemental source of calcium must be available to lay-
ing hens. The belief among most biologists who have

studied game birds is that this source of calcium is cal-
careous grit.

For a number of years, investigators disagreed on the
function of grit in the diet of gallinaceous birds—whether
erit was required by the birds for its mineral content or
as a grinding agent in the mastication of food. Nestler
(1946:141) reported that grit as a grinding agent in the
gizzard was not essential for the growth, welfare, or re-
production of pen-raised bobwhites (Colinus virginianus) .
McCann (1939:33-36) concluded that the consumption
of grit by pheasants appeared to be conditioned pri-
marily by a need for calcium.

The belief that glacial grit is required as a source
of calcium for pheasants represents an elaboration of the
elacial hypothesis set forth by Leopold (1931: 125-126).
Leopold’s hypothesis is strengthened by the fact that
many years after the initial establishment of the pheasant
in the North Central States its distribution still nearly
coincides with the area of most recent glacial activity.

In Illinois, the relationship between pheasant dis-
tribution and the area of most recent glacial activity is
evident. Four independent stages of glaciation have been
recognized in Illinois; these are, from oldest to most
recent, the Nebraskan, Kansan, Illinoian, and Wiscon-
sinan (Horberg 1950:17). The major patterns of dis-
tribution of pheasants in Illinois approximately coincide
with the moraines deposited by the substages of the Wis-
consinan ice sheet. The center of greatest pheasant abun-
dance, located in Livingston and Ford counties of east-
central Illinois, is closely associated with the Chatsworth
and Cropsey moraines of the Wisconsinan ice sheet. The
southwestern boundary of the contiguous range occupied
by pheasants terminates approximately at the southwest-
ern boundary of the Shelbyville moraine, terminal mor-
aine of the Wisconsinan glacier (Fig. 4). Some self-
maintaining pheasant populations of relatively low
numbers are found in areas in which the Il]linoian was
the most recent glacier and even on the unglaciated
areas in the northwestern corner of Illinois, but areas
supporting the greatest numbers of pheasants are found
within the area of Wisconsinan drift (Fig. 4).

The logic behind Leopold’s glacial hypothesis on the
positive relationship between pheasant distribution and
recently glaciated areas and the subsequent hypothesis
that grit from recent glacial drift is needed to provide a
source of calcium for pheasants becomes apparent when
we recognize that the drift from recent glacial activity
has undergone less weathering and, consequently, less
leaching than have the older drifts. The availability to
pheasants of grit from the less weathered and less leached
glacial drift must then be considered. With the excep-
tion of areas of some alluvial deposits, lake sediments,
and sand dunes, the state of Illinois is covered by wind-
blown deposits of loess originating from the Wisconsinan
age. These loess deposits can be eliminated from con-
sideration as a source of calcium over much of the
pheasant range in Illinois. In a large portion of Illinois,
including most of the northeastern third of the state
where pheasants are most abundant, deposits of loess

10

are shallow—4 feet or less in depth—and noncalcareous
(Leighton & Willman 1950:604, 607). The speculation
may be made that pheasants are more abundant in some
areas of shallow loess than in areas of deep loess because
erosion, plowing, or some other activity has exposed the
glacial drift, thus making calcium-bearing grit that may
be in this drift available to the pheasants. If this specu-
lation is valid, the drift on which pheasants are most
abundant (Wisconsinan) should contain more calcium
available to the birds than the drift on which pheasants
are not established (Illinoian).

In 1956, 1,726 pheasants originating from stock ob-
tained from California were released by the Illinois Nat-
ural History Survey and the Illinois Department of
Conservation on an area of Illinoian drift in Cumber-
land County. The release was made as part of a program

perme
11.5
Ve OGLE
Unglaciated 738

Bey 258)

Fic. 4.—Distribution and abundance of pheasants in Illi-
nois in relation to the most recent glaciation, the Wisconsinan.
The heavy line designates the terminal boundary of the Wis-
consinan ice sheet (after Ekblaw & Lamar 1964:4). The
figure for each county within the pheasant range represents
pheasant abundance, as determined by the mean number of
pheasants reported by rural mail carriers per 100 miles of
driving during six censuses in 1957 and 1958 (Table 1).

to introduce a strain of pheasants that would survive and
produce huntable populations south of the contiguous
range occupied by pheasants in Illinois (Ellis 1959; Ellis
& Anderson 1963). By 1959, the population had nearly
disappeared, indicating that one or more factors were
preventing the establishment or maintenance of pheasants
on this study area.

An investigation was begun to determine if a defi-
ciency of calcium might be a factor in preventing the
establishment of pheasants on this area of Illinoian drift.
The availability of calcium and its ingestion and subse-
quent utilization by pheasants on the Cumberland County
area were compared with like information from a study
area on Wisconsinan drift within the established pheas-
ant range. Only pheasants that had been hatched and
reared on the Cumberland County area were used in the
comparative analysis of calcium ingestion because the
effect of possible mineral deficiencies on the Illinoian drift
might not be immediately detectable in released birds.

The study area on Wisconsinan drift was located near
Sibley in Ford and McLean counties of east-central IIl-
nois (Fig. 4) ; it contained 23,200 acres, 19,040 in north-
western Ford County and 4,160 acres in northeastern
McLean County. The soils of Ford County were formed
from material deposited by the last invasion of the Wis-
consinan ice sheet together with wind-blown material
and some water-deposited outwash (Smith et al. 1933:8—
9). McLean County soils were formed primarily from
loess deposited after the Wisconsinan glacier receded
(Hopkins et al. 1915:2). Ford County ranked second
and McLean County fourth among Illinois counties in
the order of abundance of pheasants in 1957 and 1958
(Table 1).

The study area in Cumberland County consisted of
10,240 acres located near Neoga, about 20 miles south
of established pheasant range in Illinois (Fig. 4). Ac-
cording to Smith & Smith (1940:7), both the Illinoian
and the Wisconsinan glaciers contributed to the soils of
Cumberland County. The Illinoian ice sheet covered
the county and left a broad undulating plain that still
persists over much of the county. The Wisconsinan
glacier entered a small portion of the extreme northern
edge of the county (Fig. 4) and subsequently formed
narrow outwash plains in a number of places on the old
I!linoian glacial plain. Wisconsinan glacial drift did not
extend to the Cumberland County study area. No loess
deposits in Cumberland County are more than about 40
inches in depth and, in large portions of the county, the
deposits are so shallow that they are almost indistinguish-
able.

Calcium was available to the pheasants on both study
areas in the carbonate form as calcitic limestone, Ca-
CO,, and as dolomitic limestone, CaMg(CO,).,. Alder
(1927:232) reported that the use of dolomite for ap-
proximately 4 months caused domestic pullets to become
nervous and sensitive, develop diarrhea, and produce
fewer eggs—eggs with progressively thinner eggshells;
these symptoms rapidly cleared up when practically pure
calcium carbonate was substituted for dolomite. Dale

(1955:328-329) found that penned pheasant hens fed
crushed dolomitic limestone were much more successful
in producing eggs and chicks than were hens fed granite
grit. Harper (1963:366; 1964:269) reported that grit
from gizzards of wild pheasants, both young birds and
adult hens, contained amounts of calcite that were dis-
proportionately greater than the amounts of dolomite
when availabilities of the two materials were measured;
in fact, wild pheasants consumed only trace amounts
of dolomite. These reports suggest that calcitic lime-
stone is desirable for maximum reproductive performance
by pheasant hens.

Samples (excluding grit) of both the Illinoian and
Wisconsinan glacial soils were tested. The Illinoian sam-
ple contained 0.23 per cent calcium and the Wisconsinan
sample 0.15 per cent calcium (Harper & Labisky 1964:
725-726) , indicating that calcium was at least as abun-
dant in soils of the Illinoian drift as in soils of Wiscon-
sinan drift; phosphorus and magnesium levels were slight-
ly higher in soils from the Wisconsinan drift than in those
from the Illinoian drift.

The amount of calcium in the grit from fields and
secondary roads on the Illinoian drift was equal to that
from fields and secondary roads on the Wisconsinan drift
(Harper & Labisky 1964:725-726). The grit from roads
on both the Illinoian and Wisconsinan drift yielded 5.5 ¢
of calcium per 100 g of grit. The grit in soil samples
collected from fields of Hlinoian and Wisconsinan glacial
soils contained 0.2 g of calcium per 100 g¢ of grit.

The amount of calcium found in the grit from giz-
zards of wild pheasant hens during the nesting season
(May and June) averaged 2.3 g per 100 g of grit on the
Illinoian drift, 1960—1961, and 1.9 on the Wisconsinan
drift, 1957—1962 (Harper & Labisky 1964:727). Fem-
ora and tibiae from the pheasant hens collected from
an area on the Illinoian drift in Cumberland County con-
tained a percentage of mineral ash that was slightly higher
than the percentage of ash in the femora and tibiae of
penned pheasant hens that had received diets containing
2.34 per cent calcium and equal to the percentage of ash
in the femora and tibiae of wild hens collected from
areas of Wisconsinan drift (Greeley 1962:190, 192).
Harper & Labisky (1964:727—728) reported no signifi-
cant differences in amounts of mineral ash or calcium ash
per unit of wet tissue weight of hens collected on Illinoian
and Wisconsinan drift during the spring of 1962. Too,
grit from the gizzards of young pheasants collected on
Illinoian drift had amounts of calcium similar to the
amounts from the gizzards of young birds that were col-
lected on the Wisconsinan drift (Harper & Labisky 1964:
727-728).

In the nesting seasons of 1961 and 1962, pheasant
hens on the area of Illinoian drift in Cumberland County
(including hens released and hens hatched and reared on
the area) compared favorably with hens from self-main-
taining populations on Wisconsinan drift in (i) number
of eggs per nest, (ii) number of eggs hatched per success-
ful nest, and (iii) number of chicks per brood (Anderson
1964:259). These criteria of successful reproduction in-

dicate that the physiological utilization of calcium by
hens on the Illinoian drift was similar to that by hens
on the Wisconsinan drift.

Even if soils on the Illinoian drift contained less
available calcium than the soils on the Wisconsinan drift,
the difference might be compensated for by the apparent
ability of pheasants to be selective in the type of grit they
consume. Sadler (1961:340-341) found that penned
hen pheasants selected calcareous grit (limestone) rather
than noncalcareous grit (granite) during the egg-laying
period. Harper (1963:365—366; 1964: 269) reported that
wild pheasants in Illinois, both young and adults, selected
calcitic over dolomitic grit, as well as calcareous over
noncalcareous grit. Also, pheasant hens may possess the
ability to select calcitic grit containing high rather than
that containing low levels of calcium (Harper & Labisky
1964: 730).

Native gallinaceous birds, the bobwhite and the
prairie chicken (T’ympanuchus cupido), counterparts of
the pheasant, have established self-maintaining popula-
tions on areas of Illinoian drift in Illinois. These birds,
like the pheasant, have high calcium demands.

Our conclusion is that, in Illinois, calcium is as avail-
able to pheasants on Illinoian glacial drift as on Wis-
consinan drift, which is of more recent origin. We found
that hen pheasants and young pheasants in areas of IIli-
noian drift ingested calcium in amounts similar to the
amounts ingested by birds in areas of Wisconsinan drift;
also, that the physiological utilization of calctum by hen
pheasants in an area of Illinoian drift appeared to be
equal to that by hens from a thriving population of
pheasants in an area of Wisconsinan drift. It seems un-
likely that, in Illinois, the establishment and maintenance
of pheasant populations in areas of Ilinoian glacial drift
are prevented by a deficiency of calcium. This con-
clusion, however, does not disprove Leopold’s hypothesis
that a deficiency of some element or vitamin may pre-
vent the establishment of pheasants on areas of pre-
Wisconsinan glacial drift.

Pheasants and Weather

Weather, as well as a deficiency of calcium, has long
been regarded as a factor limiting (i) the southward
spread of the pheasant, particularly in the eastern portion
of the United States, and (ii) the abundance of pheas-
ants within portions of their established range. Pheasants
have become widely established in the northern sectors
of the midwestern and eastern United States, but, with
few exceptions, they have failed to establish self-main-
taining populations south of a line designating 40 degrees
north latitude.

Of the many stimuli or stresses to which the pheasant
is subjected, some of the most important are associated
with weather. ‘The description Selye (1949:837) gives
of the “stage of resistance,’ the second stage of the
general-adaptation-syndrome, indicates that a pheasant
hen is capable of adapting to one or more stresses but
at the expense of resistance to others. The description
of the “stage of exhaustion,” the third and final stage

12

of the syndrome, indicates that the hen may die as a
result of very prolonged exposure to stresses to which she
has become adapted; the hen cannot indefinitely main-
tain adaptation to certain stresses. Even stresses that
do not cause death may interfere seriously with the
physiological functions of the hen, particularly those asso-
ciated with reproduction. Very likely, the stresses that
weather exerts on the pheasant are fewer, less intense,
less prolonged, and less critical in the established con-
tiguous range of the bird than in range where the bird
experiences difficulty in maintaining even meager, dis-
junct populations.

Extensive losses of pheasants as a result of unfavor-
able weather conditions in winter are well documented
in the Plains and Prairie States. Winter losses of pheas-
ants as high as 90 per cent have been reported in portions
of South Dakota (Kimball et al. 1956: 211, 229) ; severe
winter losses have been reported in Iowa (Scott & Baskett
1941:28), Minnesota (Erickson et al. 1951:33—34)
North Dakota (Miller 1948:4-5), and Nebraska (Mc-
Clure 1948:268-269). These reported losses of pheas-
ants during winter in the Plains and Prairie States were
attributed mainly to the birds’ freezing and choking dur-
ing severe winter storms—storms characterized by heavy
snowfall and strong winds. That starvation is probably
not an important cause of winter mortality was demon-
strated by Tester & Olson (1959:308-309), who re-
ported that, in Minnesota, pheasants penned out-of-doors,
although losing considerable weight, could survive at
least 2 weeks without food during severe winter weather.
The cases of starvation reported by Nelson & Janson
(1949:308) in South Dakota were confined to small,
scattered areas; only about 5 per cent of the pheasants
in these areas died from starvation.

Losses of pheasants to winter weather in the Lake
States, which include Illinois, are usually much less severe
than in the Plains and Prairie States because prolonged
periods of deep snow and low temperatures are less
frequent, and food in the form of waste grains is gen-
erally abundant (Fig. 5, 6).

Even though winter weather is seldom so severe as
to cause direct losses of pheasants in the Lake States,
and particularly in Illinois, unfavorable weather condi-
tions during winter may so weaken the birds physio-
logically that they enter the breeding season in less than
adequate physical condition. Kozicky et al. (1955: 140)
pointed out that in Iowa “two months of consecutive
low temperatures from December through February were
detrimental to fall pheasant populations by reducing the
breeding stock.” Recently, Edwards, Mikolaj, & Leite
(1964:278) suggested that depressed reproductive per-
formance of pheasants was directly related to low body
weights resulting from exposure of the birds to severe
weather during the preceding winter. This promising
area of investigation—the relationship between winter
weather and reproduction — merits attention in future
pheasant research.

Rainfall and temperature, particularly during the
breeding season, have long been considered two of the

major weather factors affecting productivity and abun-
dance of pheasants. During the 1940's, pheasant popula-
tions in most midwestern states suffered drastic reductions
in their numbers (Kimball 1948:292). In Illinois, the
decline of pheasants was probably of shorter duration
than in most other states (Robertson 1958:122). There
was fairly general agreement among investigators that
unfavorable spring weather, persisting for several years in
widely separated areas, may have caused the widespread
reduction in numbers of pheasants in the 1940's (Allen
1950: 107).

Investigators in the Midwest have reported that the
production of young pheasants has been adversely in-
fluenced by unusually cool, wet springs (Allen 1947 :234—
236; Ginn 1948:4—5; Erickson et al. 1951:31—32). Kim-
ball (1948:309) reported that pheasant populations in
South Dakota during the 1940’s did not increase in
years (with one exception) in which the weather during

June was either wet and cold or unusually hot and dry.
Kozicky et al. (1955:141) reported that fall populations
of pheasants in Iowa showed decreases in years during
which the breeding season was characterized by below
normal temperatures and above normal rainfall, but
that, with above normal temperatures, amounts of pre-
cipitation apparently had no adverse effect on the num-
bers of pheasants in fall. Dale (1942:18) reported that
wet years (greater than average rainfall in June, July,
and August) were not detrimental to pheasants in Michi-
gan. The evidence regarding the influence of gross spring
weather on pheasant production and survival is not
clear-cut.

3uss, Meyer, & Kabat (1951:34—-35) reported that
both wild and artificially propagated pheasants deposited
their first eggs on approximately the same dates each
year regardless of year-to-year variations in spring wea-
ther. Although the dates of first eggs are approximately

c

Fic. 5.—Flock of pheasants in woody cover along fencerow during period of deep snow in 1960.

snow are infrequent in east-central Illinois.
woody vegetation, even though such vegetation is scarce.

Heavy accumulations of

In winter, many of the pheasants in this area are found within about 100 yards of
Pheasants are associated more often with the type of cover shown
here than with hedgerows of osage orange or multiflora rose.

13

the same each year, the dates of establishment of nests
are not. Kabat, Thompson, & Kozlik (1950:4—5, 15)
postulated that weather that causes a delay in the an-
nual hatch may place prolonged reproductive stress on
adult pheasant hens and result in an increase in the mor-
tality rate of these hens; stress in these hens, as indicated
by loss in body weight, appeared to be related directly
to the number of eggs laid. Buss, Swanson, & Woodside
(1952:280) concluded that adverse weather in early
June, 1950 (weather characterized by unseasonably heavy
precipitation and low temperatures), delayed renesting
among pheasants in southeastern Washington; the delay
subjected the hens that attempted to renest to the pro-
longed physical stress of additional egg-laying and in-
creased the rate of mortality among them. Kabat et al.
(1956:33-34) pursued further the problems of stress in
hen pheasants and showed that adult hens were in their
poorest physiological condition in July and August, to-
ward the end of the reproductive season and during

molt. Wagner (1957:308-310) more fully expounded
the evidence of accelerated late-summer mortality of
adult hens, linking it with the physiological stresses
caused by prolonged reproductive efforts, particularly
egg-laying.

Although numerous investigators have provided con-
vincing evidence that many pheasant hens die during
the reproductive and molting periods, the relationship
between their deaths and the autumn populations of
young has not been well defined. A high proportion of
young in the fall population does not necessarily indicate
a good hatch in the preceding breeding season. Wagner
(1957:313) pointed out that late-summer hen mortality
“appears to bias hen age ratios or total-population age
ratios from unhunted areas sufficiently to cause one to
form erroneous conclusions if not taken into account.”

The time of death of adult hens has an important
effect on the hatch of chicks and on efforts made to

measure the hatch. If a hen dies prior to the completion

Fic. 6.

14

One of several hundred feeding sites of pheasants in an Illinois cornfield in early March, 1960. About 400 pheas-
ants had scratched through more than a foot of compacted snow to reach waste corn in this field.

of incubation or early in the brooding period, she adds
few, if any, young to the population. If she dies after
the chicks are able to survive on their own, but prior
to fall, her death has little or no effect on the annual
production of young; however, the absence of this and
similar hens from the fall population results in higher
young-to-adult age ratios than are justified by the hatch.

Adverse weather that during the reproductive season
places unusual stress on adult hens may reduce the
production and survival of chicks by causing the hens
to give less than the normal attention to eggs or young.
Laboratory experiments by MacMullan & Eberhardt
(1953:330) suggested that inattentive incubation by nest-
ing hens, particularly during late incubation in cold and
wet spring weather, might cause lethal exposure of eggs.
These workers reported that young chicks were less
tolerant of cold, especially when accompanied by pre-
cipitation, than were eggs. If production of young is
depressed and death of adult hens accelerated by adverse
weather during the reproductive season, age ratios the
following autumn might indicate erroneously that an
average hatch of young pheasants had occurred.

When Graham & Hesterberg (1948:10-13) compared
rainfall-temperature climographs for four areas in Ore-
gon, Minnesota, North Dakota, and Michigan where
pheasants had established self-maintaining populations,
they found the greatest similarities in the climographs
of these four areas during April and May. Climographs
for areas in Missouri, Ohio, and Tennessee where pheas-
ants had not established themselves showed little or no
similarity during April and May to the climographs for
the four areas occupied by pheasants. Graham & Hester-
berg (1948:10) concluded that “if the distribution of
pheasants is limited in any way by temperature or pre-
cipitation the effects must be during the spring season.”

Thus far, in this paper, little attention has been
given to measuring directly the influence of summer rain-
fall on the hatch of pheasant chicks. In the established
pheasant range in Illinois, June is the month during
which about 50 per cent of the annual crop of chicks
is hatched. Heavy rainfall during June might exert two
opposing influences on the hatch of pheasant chicks in
this area. First, heavy rainfall so timed as to occur
during a period when a sizable portion of the annual
hatch was very young might result in the mortality of
many young chicks, particularly if the rains were ac-
companied by cold (MacMullan & Eberhardt 1953:330).
Second, excessive rainfall during early June would tend
to delay mowing of tame hay, thereby allowing many
nests to hatch that would normally be destroyed by
mowing.

To determine what effect, if any, the amount of rain-
fall in June, 1957 and 1958, had upon the hatch of
chicks within the established range of pheasants in Illi-
nois, we plotted rainfall for this month against the
number of chicks observed per 100 miles of driving by
rural mail carriers during August of the same years in
each of the 25 counties in which pheasants were most
abundant (Fig. 7). The long-term average rainfall dur-

ing June for these 25 counties (Page 1949:201—294)
was 3.9 inches. In 1957 and 1958, rainfall in June
averaged 5.1 and 7.0 inches, respectively, for the 25
counties; thus, in June of both years, rainfall was above
the long-term average. The average amount of rainfall
recorded in June, 1958, was significantly greater than
that recorded in June, 1957 (t = 3.73; P < 0.01). The
mean number of chicks per 100 miles of driving in the

IN| AUGUST

100 MILES

ol
je)

CHICKS PER
)
ie}

Di Sein Ga 7A GUE OmLIO
INCHES OF RAINFALL IN JUNE

Fic. 7.—Abundance of pheasant chicks reported by rural
mail carriers per 100 miles of driving during August in rela-
tion to rainfall during the preceding June for each of the 25
Illinois counties in which pheasants were most abundant
(Table 1), 1957 and 1958. The rainfall data are from the
United States Weather Bureau (1957, 1958).

25 counties during August was 6.8 in 1957 and 6.0 in
1958. The difference in the abundance of chicks between
August of 1957 and August of 1958 was not significant
(¢ =0.48; P> 0.50), but fewer chicks were observed
in 1958, which was characterized by more rain during
June than was 1957.

Statistical tests by linear regression indicated that
there was no significant correlation (0.05 level) between
the amount of June rainfall and the abundance of chicks
in the 25 top-ranked pheasant counties of Illinois in
August of 1957 or 1958 (Fig. 7; 1957: b =0.216, F =
0.10, Reference F = 4.28 at 1 and 23 d.f.; 1958: b=
0.589, F = 1.25, Reference F = 4.28 at 1 and 23 d/f.).

The abundance of chicks in August appeared to be
less in counties where rainfall measured between 5 and
6 inches during June than in counties with amounts of

15

rainfall less than 5 inches or greater than 6 inches (Fig.
7). However, when tested for curvilinearity of regression
(Snedecor 1956:452-457), these data yielded no statis-
tical significance (0.05 level) for either August, 1957, or
August, 1958 (1957: estimated Y = 220.0 — 1.189X +
0.1343.X7, F —0.15, Reference F = 3.42 at 2 and 22
d.f.; 1958: estimated Y = 22.94 —6.490X + 0.5518X°,
F — 0.67, Reference F = 3.42 at 2 and 22 d/f.).

Another weather factor, that of evapotranspiration
(evaporation from the soil surface and transpiration from
plants) has been suggested by McCabe, MacMullan, &
Dustman (1956:322-325) as a possible influence on the
distribution of pheasants in the Lake States. These
workers reported “an almost perfect correlation” be-
tween the distribution of pheasants in the Lake States
and the mesothermal B’, region as classified by the
climatologist Thornthwaite (1948:81, 87, and pl. 1C).
This region has a potential evapotranspiration of 22.44
inches along its northern boundary (north of the central
portions of Wisconsin and Michigan) and 28.05 inches
along its southern boundary (near the central portions
of Indiana and Illinois). An exception to this “‘correla-
tion” is found in Illinois, where a portion of the best
pheasant range in the east-central sector of the state falls
south of the mesothermal B’, region. The cause-and-
effect mechanisms of the apparent relationship between
evapotranspiration and pheasant distribution are not
known.

Bennitt & Terrill (1940:428) established a working
hypothesis that the barrier limiting the southward ex-
tension of the range of the pheasant might be “high: egg
temperature and the resulting mortality of embryos,” or,
in other words, embryonic mortality resulting from the
exposure of clutches to high air temperatures in spring
or summer. Graham & Ieieowbare (1948:12, 14) postu-
lated that the southern limit of pheasant distribution
might be determined by the extent of embryonic mor-
tality caused by direct exposure of clutches of eggs to
the sun’s rays during the preincubation period.

Yeatter (1950:529-530) was the first worker to con-
duct experiments to determine the influence of air tem-
peratures in defining the southern limits of the range
of the pheasant. He observed a sharp decline in suc-
cessful hatches and in the number of chicks produced
per clutch along the southern fringe of the pheasant
range in east-central Illinois after the first week of July:
nest studies suggested that this decline in production re-
sulted from a decline in hatchability of eggs, a decline re-
sulting from embryonic mortality and not from decreased
fertility. "To test the postulate that the mortality of em-
bryos might be attributed to exposure of the clutch to high
temperatures during the preincubation period, a time at
which the hen does not control the temperature of the
clutch, Yeatter obtained pheasant and bobwhite eggs from
Illinois game farm stock and exposed them to different
air temperatures between 62 degrees F (control) and 88
degrees F during 9-hour periods (8:00 a.m. to 5:00
p-m.) for 7 consecutive days prior to incubation. he
pheasant eggs exposed under these conditions showed a

16

progressive decline in hatchability from a high of 75.0
per cent at 62 degrees F, the control temperature, to a
low of 42.1 per cent at 88 degrees F, while hatchability
of the quail eggs, similarly exposed, declined from a high
of 76.2 per cent at 62 degrees F to 68.4 per cent at 88
degrees F. These data suggested that high air tempera-
tures during the laying period had an important influence
in limiting the southward spread of the pheasant in IIli-
nois and other states.

To further test this postulate, Yeatter obtained eggs
from two strains of pheasants, one strain from California
and the other from Wisconsin. When the eggs from
these two strains were subjected to similar preincuba-
tion temperatures of 62 degrees F (control) to 88 degrees
F, the eggs from the California stock showed greater
hatchability than did the eggs from the Wisconsin stock
(Ralph E. Yeatter, Illinois Natural History Survey, Ur-
bana, 1962, personal communication) . These experi-
ments, when considered alone, suggested that the ability
of pheasant embryos to survive under conditions of high
air temperatures may have been the operative force
in the natural selection of a strain of pheasants able
to withstand the climate of California, and that the
pheasant now resident in the Midwest has failed to be-
come established when it has been released south of its
present contiguous range because of its lack of genetic
adaptation to high air temperatures. However, it seems
illogical to assume that natural selection of individuals
with the genetic aptitude necessary to withstand higher
air temperatures would not occur along the southern
margin of the range currently occupied by the pheasant
in the Midwest, thus allowing the bird to gradually ex-
tend its range southward into previously unoccupied
range. Perhaps not enough time has elapsed to create a
gene pool of traits that would allow a measurable and
permanent spread of the pheasant into areas of higher
temperatures.

That high air temperatures alone probably do not
limit the southward extension of pheasants is indicated
by the observations of Ellis & Anderson (1963:225).
Pheasants originating from California stock failed to
establish self-maintaining populations after being released
on two areas south of the contiguous pheasant range in
Illinois (Ellis & Anderson 1963:225). Among the Cali-
fornia pheasants and their progeny, Ellis & Anderson
(1963:234) reported, “There were no differences in the
average number of chicks in broods hatched from nests
exposed to temperatures that exceeded 79 F on 7 or more
days during the preincubation period when compared to
the average number of chicks in broods from nests not
exposed to such temperatures.” These workers (Ellis &
Anderson 1963: 236; Anderson 1964: 263) concluded that
the failure of liberated pheasants and their progeny to
establish themselves south of the contiguous range occu-
pied by pheasants in Illinois was due more to inadequate
survival, particularly during fall and winter, than to in-
adequate reproduction.

This discussion of pheasants and climate has shown
the degree of complexity with which we are faced when

we attempt to explain abundance and distribution of
pheasants by weather factors. We know too little about
these factors and their effects. As McCabe et al. (1956:
324) pointed out, “What to the pheasants are ideal
climatic conditions are not necessarily those measured
by weather stations, . . . .’ Undoubtedly, weather exerts
a considerable influence on established pheasant popula-
tions, particularly with respect to annual fluctuations.
On areas occupied by only a few pheasants, unfavorable
weather may limit the dispersion and abundance of the
population by annually depressing production or by in-
creasing the mortality rates, or both. In unoccupied
range, the cumulative effect of these factors might be so
great as to preclude the establishment of self-maintaining
populations.

We hypothesize that, in areas where factors other
than weather are favorable to the bird, pheasant popu-
lations may be limited not by adverse weather conditions
in any one year but rather by the frequency, severity, and
duration of adverse conditions over a period of years.
We may therefore speculate that adverse weather, as
well as other adverse environmental factors, occurs less
frequently, with less severity, and for shorter periods in
the range occupied by pheasants than in the range un-
occupied by pheasants. The validity of this hypothesis
will be determined only after completion of long-term
ecological studies of pheasants in areas characterized by
different levels of pheasant abundance.

Summary

In Illinois and other midwestern states, populations
of pheasants are characterized by discontinuous distribu
tion and by variable abundance. This paper reviews pub-
lished findings and presents new data on three factors,
land use, calcium, and weather, all commonly considered
as important influences on the distribution and abun-
dance of pheasants in Illinois.

The intensively cultivated cash-grain area of east-
central Illinois has consistently supported the best popu-
lations of pheasants in the state since the late 1930's.
The following land-use practices were found to be char-
acteristic of many of the counties in Illinois where
pheasants were most abundant: (i) a high proportion
of the land in cultivated crops and a low proportion in
woodland, (ii) a high proportion of the farms classified
as cash-grain farms and a lower proportion as dairy farms
and livestock farms, and (iii) about 50 per cent of the
cropland in corn and soybeans, about 5 per cent in hay,
and about 15 per cent in pasture. A multiple regression
analysis indicated that a combination of three land-use

factors, (i) the proportion of land in cultivated crops,
(11) the proportion of farms classified as cash-grain farms,
and (iii) the proportion of cropland in hay, when tested
against all other land-use factors, exerted the greatest in-
fluence on the distribution and abundance of pheasants
in Ilhnois.

In Illinois and other North Central States, the distri-
bution of pheasants coincides closely with that area
blanketed by the Wisconsinan glacier, the last of the
major ice sheets. Pheasants have seldom established
themselves on Illinoian glacial drift, which in Illinois
underlies and extends south and west of the Wisconsinan
drift. The Illinoian glacier was the immediate predeces-
sor of the Wisconsinan glacier. A supposed deficiency
of calcium in the soils and grit on areas of exposed
Illinoian drift has long been regarded as a factor limiting
the southward spread of the pheasant in the North
Central States. In Illinois, the amounts of calcium in
the soils and grit in an area of Illinoian drift, where
pheasants have not established self-maintaining popula-
tions, were equal to or greater than the amounts from
similar items in an area of Wisconsinan drift, where
pheasants are abundant. The amounts of calcium in the
grit from gizzards of hen pheasants and young pheasants
on Illinoian drift were very similar to those amounts
found in the grit from gizzards of hens and young on
Wisconsinan drift; also, the subsequent utilization of in-
gested calcium by hen pheasants on the IIlinoian drift
appeared to be equal to that by hens from a thriving
population on the Wisconsinan drift. It is unlikely that,
in Illinois, the establishment of self-maintaining pheas-
ant populations on areas of Illinoian drift is prevented
by a deficiency of calcium.

Unfavorable weather is partially responsible for year-
to-year fluctuations in numbers of pheasants within their
established range. On areas occupied by only a few
pheasants, unfavorable weather may limit the dispersion
and abundance of the population by annually depressing
production and by increasing mortality rates. In unoc-
cupied range, the cumulative effect of these factors might
be so great that the establishment of pheasants would be
prevented. In areas where factors other than weather
are favorable to the bird, pheasants may be limited not
by unfavorable weather in any one year but rather by
the frequency, severity, and duration of adverse weather
over a period of years. Adverse weather, as well as other
adverse environmental factors, probably occurs less fre-
quently, with less severity, and for shorter periods in the
range occupied by pheasants than in the range not oc-
cupied by pheasants.

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