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Title: Food of the Crow, Corvus brachyrhynchos Brehm, in South-central Kansas
Author: Dwight Platt
Release Date: August 27, 2010 [EBook #33545]
Language: English
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UNIVERSITY OF KANSAS PUBLICATIONS
MUSEUM OF NATURAL HISTORY
Volume 8, No. 8, pp. 477-498, 4 tables
June 8, 1956
Food of the Crow, Corvus brachyrhynchos Brehm, in South-central Kansas
BY
DWIGHT PLATT
UNIVERSITY OF KANSAS
LAWRENCE
1956
UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY
Editors: E. Raymond Hall, Chairman, A. Byron Leonard,
Robert W. Wilson
Volume 8, No. 8, pp. 477-498, 4 tables
Published June 8, 1956
UNIVERSITY OF KANSAS
Lawrence, Kansas
PRINTED BY
FERD VOILAND, JR., STATE PRINTER
TOPEKA, KANSAS
1956
FOOD OF THE CROW, CORVUS BRACHYRHYNCHOS BREHM, IN SOUTH-CENTRAL KANSAS
By Dwight Platt
Introduction
The yearly diet of the crow was studied from December, 1952, to
February, 1954, in Harvey County and the northeastern townships of Reno
County, in south-central Kansas. In the United States much attention has
been devoted previously to the food taken by the crow because it is of
economic importance. The work of Barrows and Schwarz (1895) was the
first of a series of studies made by the United States Department of
Agriculture. Kalmbach (1918, 1920, 1939) continued these studies by
analyzing stomach contents from various parts of the United States. Also
the diet of the crow has been studied by local areas (Imler--Oklahoma,
1939; Hering--New York, 1934; Black--Illinois, 1941; Lemaire--Louisiana,
1950).
I am grateful to Dr. Henry S. Fitch, for many valuable
suggestions and helpful encouragement given in the course of
my study. Professor E. Raymond Hall, who read the
manuscript, likewise offered valuable suggestions. Dr. R. L.
McGregor and Mr. Wilford Hanson provided invaluable
assistance in identification of plants and insects found in
the crow pellets.
Methods
Previous studies were based mostly on analyses of stomach contents. My
study is based on the analysis of 617 regurgitated pellets collected
from roosts and lookout posts. Fifty-three collections of pellets were
made throughout the year at regular intervals, except that none was made
in January, March, or May. The pellets were wrapped individually in
paper or leaves as collected, and each was analyzed separately. The
percentages by bulk of different food residues (excluding sand and other
extraneous material) were estimated in each pellet and recorded.
Description of the Study Area
The study area is on the eastern edge of the Great Bend Prairie
physiographic province of Moore (1930). The climate is characterized by
moderate precipitation (ann. 30"), a wide range of temperature
variations, moderately high wind velocities, and comparatively rapid
evaporation. The summers are generally hot, and the winters are
moderately cold but are free from excessive snowfall. The weather during
the study period was unusually dry, and the summer temperatures were
above normal. A drought had begun in 1952, following the cool and wet
summer of 1951.
The study area includes the zone of transition from bluestem or
tall-grass prairie to the buffalo grass or short-grass prairie. The
principal farm crop in the study area is wheat. Sorghum grain, oats, hay
crops (especially alfalfa), and corn are also grown. The study area
supported a small population of breeding crows; an estimate based on
field observations mainly in eastern Harvey County, was not more than
one pair per square mile. In winter a large population of crows migrates
into the area from the northern Great Plains. Censuses showed that on
parts of the area the feeding population might be as great as 180 birds
per square mile. These wintering crows concentrate in the western part
of the study area where the flat, fertile wheat fields of central Harvey
County are replaced by sand dunes and the sandy Arkansas River Valley.
Here much land is devoted to raising livestock, and sorghum grain is an
important field crop. There is also more waste land there than elsewhere
in the area.
Data From Analysis of Pellets
Data obtained from the analysis of pellets were grouped in biweekly
collections, and percentages of various food residues in the pellets
collected within each biweekly period were averaged. Also frequency of
occurrence was computed, and maximum and minimum percentages were
included to permit a broader interpretation. In determining the minimum
percentage, only those pellets were considered in which the food residue
was present.
Pellets from roosts of resident crows were collected on a year round
basis in eastern Harvey County near Newton (see tables 1 and 2). The
data from these pellets were interpreted separately from data on
collections made in the western part of the study area from under roosts
of wintering crows (see tables 3 and 4).
In studies of the food of owls analysis of materials in regurgitated
pellets has been widely used, but with crows this method has been little
used because the nature of their food makes identification of material
more difficult. Analysis of pellets has certain merits, however, and, if
closely correlated with field studies, can give valuable information
concerning food habits. The availability of pellets and the ease of
collecting them are obvious advantages. Under large roosts in winter the
number that can be collected is almost unlimited. At other seasons,
pellets are scarcer, but even so they usually are more available than
stomachs.
The technique of pellet analysis is more easily applied to a study of
the yearly diet than is the technique of stomach analysis. The crow is
euryphagous and, as shown by this study, the diets of crows a few miles
apart may differ. Therefore a study made on a limited area within one
biotic community, on a year round basis, and correlated with changes in
the habitat should be of greatest value. For such a study, collection of
stomachs is not practical unless individuals are abundant so that many
can be sacrificed, but collection of pellets is practical and
profitable.
One limitation of data based on material from pellets is the
impossibility of closely correlating the volume of indigestible residues
with the proportion of food items actually eaten. Such correlation is
prevented not only by the different percentages of indigestible residues
in different food items but also by irregularities in regurgitation and
in the efficiency of the crow's digestive system. Barrows and Schwarz
(1895:24-25) cite several instances of such irregularities in captive
crows. In certain pellets that I studied, part of the wheat or other
grain was undigested or partly digested, whereas in other pellets the
only residue was finely divided chaff. Certain foods that lack hard
parts may leave no recognizable residues in pellets. A captive crow that
I raised did not form pellets when fed soft food. Nevertheless, data
from analysis of pellets when supplemented by field observations, should
serve as a sound basis for valid conclusions concerning the relative
proportions of various foods eaten. The following field observations of
habitat factors aid in interpreting the information obtained from pellet
analysis.
Field Observations and Correlations
RESIDENT CROWS IN EASTERN HARVEY COUNTY.--Although no field observations
were made on feeding behavior in April, the large percentage of oat
hulls found in the pellets suggests that newly sown fields of oats must
have been one of the major feeding grounds in that month. Oats were
planted between February 15 and March 20.
The pellets collected in June were all from the roost of one family
group of crows. This group spent much time in a cherry orchard and in
the shelterbelt near it. Residues of cherry and wheat constituted the
only plant foods found in the pellets. In both frequency and percentage,
scarabaeid beetles constituted the other important food source. The
wheat harvest started on June 17.
The cherry harvest was over by June 29. Grain harvest was over and the
fields were being plowed by July 2. Alfalfa was being cut for hay in
early July and crows were then feeding on plowed fields and the newly
mown alfalfa fields. Much time in the middle of the day was spent along
the creeks where crayfish could be obtained. During most of the summer,
pellets were difficult to find because the roosts were small, shifting,
and scattered and because few pellets were produced. For weeks at a time
there were no usable pellets under roosts occupied by hundreds of birds,
although droppings and feathers were present. At other times large
collections of pellets could be gathered from small roosts. Plowing was
a major farm operation at the season when pellets were most scarce.
Larvae of insects (especially beetles), and earthworms might have
provided a major source of food which lacked sufficient indigestible
material to form pellets. A few feces were collected and analyzed in an
attempt to find the residue of such soft-bodied foods. Indigestible
materials were found in the feces, but these were of the same types as
those found in the pellets. Only a few fragments were found which might
have been the mouthparts of grubs.
After mid-July pellets were common under one small roost. In late July
they were scarce, even at a roost with several hundred crows. The
principal feeding grounds of crows were stubble fields and plowed
fields. All grain picked up at this time was waste. Plowing was
interrupted by rain from July 11-18 but was the major farm operation
again after July 19.
From late July into early September crows fed in plowed fields, stubble
fields, pastures, and newly mown hay fields. Pellets were scarce,
considering that hundreds of crows used the roost where pellets were
collected. Plowing was almost over by July 31. Brome grass was in full
head during the early part of this period. Corn was in the milk stage
during the early part of August but did not show up in any pellets.
Although Sudan grass was in head during the early part of this period,
other sorghum did not head out until September.
From early September to early October sorghum was in full head. The
crows spent most of their feeding time in plowed fields, stubble fields,
or pastures. Much time was spent along creeks where pools, which
contained many small fish, were drying. Pellets were common under a
small roost. Grasshoppers and beetles were the two staple foods in the
diet at this time, as shown by their high frequencies and high
percentages in pellets. The high percentage and frequency of wheat
corroborates the observation that most of the feeding was being done in
wheat fields. The relatively large percentages of fish bones, crayfish,
and snail shells can be correlated with the observation that much time
was spent by the crows at the pools in creek beds. Many ants were in the
pellets. The total percentage of animal materials in the pellets was
much higher in this period than in other periods. Plant material had
been the highest, percentagewise, during most of the summer, except in
the latter part of July. Most studies of food of the crow have shown a
higher content of animal material during the summer than does my study.
It would seem that much of the food material which did not show up in
pellets during the summer was animal material.
Grasshoppers predominated in the diet in early October; some pellets
consisted of little other than grasshopper mandibles and leg joints.
Wheat is sown in this area from September 10 to October 15, most of it
being sown after October 5, the recommended Hessian fly-free date. Most
of the grain sorghum is harvested by mid-October. However, the
utilization of both of these items was low in October. By October 10
only one pool was left in the creek bed under observation. The amount of
fish bones, crayfish, and snail shells in the pellets decreased during
this period.
Killing frosts occurred in mid-October. The percentage of grasshoppers
in the diet then declined rapidly and later in the autumn declined more
slowly. Nevertheless, grasshoppers and beetles remained the predominant
animal-food residues into December and frequencies of occurrence
remained relatively high.
As autumn progressed and insects became scarcer, plant material made up
an ever-larger percentage of the diet. Wheat and sorghum constituted
more than one-half of the food residues in this period. However, in
December utilization of sorghum by resident crows in eastern Harvey
County decreased. Sorghum is not an important crop in this area.
ROOSTS OF WINTERING CROWS.--The collections of pellets from roosts of
wintering crows in western Harvey County and northeastern Reno County
differed in having a higher percentage of plant material. Sorghum, corn,
and wheat predominated in early autumn, while sorghum, sunflower seed,
and corn predominated in the winter. Ants were utilized to a much
greater extent in early autumn. For grasshoppers and beetles, frequency
of occurrence was high but percentages were low. Most of the standing
water in the sand dune country had dried approximately one year before,
and the aquatic component of the diet was almost entirely lacking.
The two principal food items taken by crows in the winter of 1953 were
grain sorghum and sunflower seed. Censuses in late November and late
December, 1953, showed that feeding was mostly in harvested sorghum
fields and corn fields, but alfalfa fields, wheat fields, plowed fields,
and native pasture were also utilized.
Sorghum and sunflower seeds were also the staple foods during December,
1952. Oats and wheat showed higher percentages than in 1953, perhaps
because different foods were available in these two winters or because
of differences in locality. The pellets collected in 1952 were from
western Harvey County, whereas most of those collected in 1953 were from
northeastern Reno County.
The collection taken in February, 1954, showed a large percentage of
oats in the diet. Newly sown oat fields were probably a major source of
food at that time.
Economic and Ecologic Significance
The chief factors that determine the economic bearing of crows locally
are: the yearly diet, the time of year in which each food item is taken,
and fluctuation in the population density at different times of year. In
the study here reported upon, the yearly diet was computed by averaging
the percentages of each item determined for each biweekly period. Of the
twenty-one collecting periods shown in the tables, six are overlapping
pairs; that is to say, each includes one collection from eastern Harvey
County and one from the western part of the study area. The average of
these pairs was used in computing the yearly average. The yearly average
is therefore based upon eighteen separate samples.
The percentages are weighted toward the food items taken in summer and
autumn, since many biweekly periods in late winter and early spring are
not represented. Of the collecting periods represented, two were in
spring, six were in summer, seven were in autumn, and three were in
winter. Pellets collected at a number of different localities are
averaged together as a percentage; consequently the figures obtainable
do not necessarily represent the diet of any one group of crows.
Nevertheless the percentages obtained by this method are perhaps valid
as a general indication of the diet of the crows in this area.
In my samples, plant material amounted to 69 per cent of the
indigestible residues. Similar percentages have been found in other
studies, ranging from 57 per cent (Barrows and Schwarz, 1895:72) to
71.86 per cent (Kalmbach, 1918:43). The percentage of plant material was
highest in the winter. In one collection from a wintering crow roost it
amounted to 99.5 per cent. In December in eastern Harvey County it
averaged only 85.3 per cent. The lowest percentage (20) was found in the
first half of October in eastern Harvey County when grasshoppers
amounted to more than half the diet. At this same time pellets collected
from the wintering roosts contained 72.4 per cent plant material.
Percentages of the chief items in the total food residues,
and (in parentheses) number of sampling periods in which
each item was represented, are shown in the following list:
wheat 23.2 per cent (20), sorghum 15.2 (16), oat 7.8 (8),
sunflower 7.2 (8), corn 5.4 (12), brome 4.2 (5), other grass
2.4 (7), cherry 1.2 (2), beetle 13.3 (21), grasshopper 9.3
(19), ant .7 (3), miscellaneous insect .2 (2), mammal 2.6
(19), bird .8 (1), eggshell .5 (3), snake .1 (2), fish .9
(9), crayfish 2.4 (12), snail .2 (9).
Wheat is the "staff-of-life" of the crows in south-central Kansas and
the percentage recorded in the diet in my study is much higher than the
percentages found by other investigators. Wheat, being the principal
crop in this area, was a readily available food. The fluctuations in the
use of wheat were due to fluctuations in the availability of other foods
that were preferred. In eastern Harvey County wheat consumption was
35.7 per cent of the diet in the latter part of July, and 49.1 per cent
in December.
Consumption of wheat was high (34.4 per cent) during the harvest in
June. However, this does not indicate serious damage since the crow
population at this time was low, and much of the wheat eaten probably
was shattered waste grain. When plowing began, wheat consumption was
much reduced. At the time wheat was sown, September 10 to October 15,
consumption was average to low.
In western Harvey County wheat was less important in the diet of
wintering crows. After reaching a peak (22.7 per cent) in October, just
after sowing, it steadily decreased, varying from 6.9 per cent to none
in December.
The wheat consumption of crows has little significance economically. No
instances of damage were reported to me either at the time of harvest or
at the time of sowing. Although crows undoubtedly do eat wheat from
newly sown fields, this utilization seldom damages the stand. No
evidence of pulling young wheat was found. Most wheat eaten was waste
grain.
Grain sorghum was the staple food of the wintering crows. In eastern
Harvey County, where sorghum is not an important crop, its consumption
began in August, reached a peak in the last part of November, and fell
off sharply in December. The grain sorghum crop is vulnerable to damage
by crows and it is ripening in the autumn as the crow population is
building up. In certain areas and certain years the loss may be
important. An exceptional instance was reported to me of crows taking 40
per cent of the crop from a small field of early ripening sorghum near a
roost. Most farmers and county agents interviewed thought that the
over-all damage was not great. The crop is usually combined and little
remains in the fields after October, when the majority of wintering
crows arrive. Nevertheless, even waste grain picked up after harvest
should be counted as a loss on some farms where stock are turned in to
clean up such grain.
Oats were taken sparingly as waste grain in summer, autumn, and winter,
and most were eaten in late winter and early spring from newly sown
fields (37.2 per cent of the February diet and 72.6 per cent of the
April diet). These percentages were probably high, since there is a high
proportion of indigestible residues in oats. This is more than
compensated for in the yearly average by the paucity of collections
made in the period when consumption of oats was highest.
Fields newly sown to oats provided a major supply of food in the early
spring when other food supplies had been depleted. However, no instance
of damage to a stand of oats was reported to me. Aldous (1944:294)
mentioned that crows fed on spring-sown oat fields in Oklahoma but
suggested that they picked up only grain which was not covered.
Sunflower seeds, although not important as a food of the crows in
eastern Harvey County, were a staple food of these wintering in the
western part of the study area. Consumption of sunflower seeds began in
September. In the latter part of December the percentage increased and
many pellets were composed entirely of sunflower seed hulls. Sunflower
seeds have a high percentage of indigestible residue.
In both popular accounts and scientific studies, the economic
significance of the consumption of weed seeds such as those of
sunflowers by birds often has been interpreted in an oversimplified
manner. It has been assumed that if crows eat several million sunflower
seeds in the winter, the sunflowers growing in the farmers' fields the
next year will have been reduced by the same number. However, like most
annual plants, sunflowers produce a great surplus of seeds each year.
Most of the seeds consumed by crows would never have a chance to grow to
maturity, even if they were not eaten. Therefore this component of the
crow's diet is only slightly beneficial or neutral for the farmer. The
effect of crows (or of the entire bird population for that matter) upon
the sunflower crop in the farmers' fields is probably slight.
Corn is one of the preferred foods of crows, but little corn was grown
in the study area. Other investigators have found higher percentages
elsewhere. In eastern Harvey County corn reached its highest point in
December but was insignificant in the diet. In the western part of the
study area it made up a larger percentage of the diet of wintering
crows. The corn eaten early in the season was undoubtedly from the
standing crop. However, most of that picked up in late autumn and in
winter was waste grain. Since little corn was shocked and left in the
fields, there was less opportunity for damage. The amount of corn
pulling at planting time was not determined, since no pellets were
collected then. However, the population of crows at that time was low. I
received no complaints of such damage to corn nor of significant damage
to the corn crop at other seasons.
There were pastures of brome grass in the area under study in eastern
Harvey County, and the seeds seemed to be a preferred food, constituting
a major food supply for the crows in the latter part of July and the
first part of August. Having a high content of indigestible residues
they probably showed up in the pellets in percentages out of proportion
to their importance in the diet. They were unimportant in the diet of
wintering crows in the western part of the study area. This component of
brome grass in the diet was economically of little significance in the
study area, although it could be of significance where brome grass seed
was being harvested.
Cherries were recorded only in June and only from one family of crows in
eastern Harvey County; cherry orchards are few in this area. The damage
done by the crows in the cherry orchard was slight, since only a few
crows fed there.
Weed seeds such as those of spurges (_Euphorbia_), ragweed, and pigweed
were found in trace amounts in the diet of the crows. However, they were
not preferred foods, since they were available in large quantities.
Wild fruits such as grape and pokeberry also showed up in trace amounts.
Elsewhere, investigators have found wild fruit forming a major source of
food in winter. However, it was not readily available in this area.
Plant fibers and seeds unidentifiable with the resources at hand formed
2.2 per cent of the residues.
It was reported to me that crows caused damage to watermelons which are
extensively grown in the sandhills region but no residues of this crop
were found in any pellets collected.
Insects were most important in the animal portion of the food. The
economic and ecologic significance of insects in the diet of birds is
often oversimplified. The effects of predation upon animal populations
are complex, and predation is often a by-product of population rather
than a controlling factor.
A female insect eaten before oviposition has a greater ecologic
significance than one eaten after she has laid her eggs and is ready to
die.
Beetles made up more than half of the insect component of the diet.
Scarabaeids were readily recognizable. Other beetles were classified as
predaceous or non-predaceous according to the type of mandibles found.
When mandibles were lacking the occurrences were listed merely as
unclassified beetles, and those made up 5.6 per cent of the yearly food
residues. Predaceous beetles made up 3.3 per cent, whereas
non-predaceous beetles made up only 1.3 per cent. Both were found in
one-half of the collecting periods. Predaceous and non-predaceous
beetles formed 1.2 per cent of the yearly food residues. This
preponderance of predaceous beetle material is what might be expected
from the manner in which crows feed. Many predaceous ground beetles of
the family Carabidae would be found under rocks and clods and on the
ground.
Beetles were a constant component of the diet in summer. They reached a
peak of 48.7 per cent in the last part of July. In November the
percentage declined and by December they formed only 2.5 per cent of the
diet.
Scarabaeid beetles were utilized in large quantities when they were most
abundant; they made up 28.7 per cent of the diet in the latter part of
June. The larvae of scarabaeid beetles are destructive to wheat and
alfalfa and live in the ground from one to three years before
metamorphosing into adult beetles. Adults emerge from the ground from
April to mid-August, the maximum flight occurring in May and June. Most
of the eggs are laid from the last of May to the middle of July (Hayes,
1920:306). Afterward the adults soon die. Many of the beetles are
nocturnal, but some of the more important destructive forms are diurnal
(Hayes, 1918:142). Crows pick up the diurnal forms when they are active
and perhaps find the nocturnal forms under clods or in burrows and eat
them in ecologically significant numbers.
Crows are beneficial to the farmer insofar as they control the
populations of scarabaeids and other non-predaceous beetles. However,
destruction of predaceous beetles is harmful to the farmers' best
interests.
Grasshoppers, second only to beetles in the insect component of the
diet, are among the most destructive insects in Kansas. Eggs laid in
autumn overwinter and hatch the next summer, from April to August,
depending upon the species. The maximum numbers of grasshoppers are
present in late summer and early autumn and they continue feeding on
crops until the first killing frost. The greatest damage is caused by
the destruction of the foliage of corn, wheat, and alfalfa (Smith, _et
al._, 1943:126). The consumption of grasshoppers closely followed the
curve of their availability, since they are a preferred food of the
crow. They were picked up in small quantities even in winter. In summer
they made up 6 to 10 per cent of the diet of the crows in eastern Harvey
County. Through the late summer and autumn this percentage rose, until
during the first half of October they made up 59.6 per cent of the
diet. However, in the western part of the study area, they constituted a
smaller part of the diet.
Predation upon grasshoppers, especially in summer and early autumn,
benefits the farmer by helping to stabilize populations of grasshoppers.
However, when grasshopper consumption was highest, in early October,
many of those eaten probably already had completed their breeding cycle,
and their consumption was hence of little significance economically or
ecologically.
Ants were consumed only in September and October when they constituted
as much as 14.9 per cent of the diet. Crows may make an entire meal from
a large colony; at any rate, whenever ants were found in a pellet, they
constituted a large percentage of it.
Miscellaneous insect remains constituted two-tenths of one per cent of
the yearly diet. Hemipteran remains were present only in trace
quantities (.5 per cent of the July 13-26 sample from eastern Harvey
County).
Only a few questionable fragments from insect larvae were found in the
pellets collected in the course of this study. However, as mentioned
earlier, there is evidence that larvae constituted a major food supply
during much of the summer.
Many investigators have found that crows feed on grubs and caterpillars
(Aldous, 1944; Alexander, 1930; Lemaire, 1950; Kalmbach, 1918; Barrows
and Schwarz, 1895). A number of county agents with whom I had
correspondence mentioned that crows aided the farmer in this way. More
investigation is required to determine the significance of crow
predation upon insect larvae in this area. Most of the bone material
recorded was fragmentary. Phalangeal or podial elements of rodents and
various bones of rabbits were identified. The only teeth identified were
those of the genus _Rattus_. Barrows and Schwarz (1895:24-25) found that
small bones of mammals may be completely ground up and digested by the
crow. Hence the amount of food furnished by mammals, either alive or as
carrion, may be higher than my figures indicate.
Bones of birds were found in only one pellet, obtained in early July.
However, few pellets were collected in the nesting season.
The eggshell occurring in the pellets probably was indicative of
extensive feeding on dumping grounds, and I received no reports of eggs
lost to crows on poultry farms. Such damage has been reduced to a
minimum since most poultry flocks are well-housed.
The percentage of aquatic animals (fish, crayfish and snail) in the
diet increased during the early autumn, as the creeks dried up in
eastern Harvey County, but after mid-October declined rapidly, as all
the pools were then gone.
Conclusions
The large wintering flocks of crows are important consumers of grain
sorghums in south-central Kansas. In the early autumn when the crow
population is building up, it damages the sorghum crop before harvest.
The damage varies from year to year, being much more keenly felt in dry
years when the crop is poor or in years when the crop is late. However,
most of the sorghums, which are the principal item of diet of these
wintering crows, are waste grain taken from the fields after harvest.
Some of this waste grain taken should be counted as a loss because the
farmer would normally let his livestock utilize it.
Crows use newly sown oat fields as a major source of food during the
late winter and early spring. However, damage to the crop is slight.
Corn is not an important crop in this area. The crow population is low
at the season when corn is planted, so probably little damage is done at
this time. Much of the corn eaten in winter is waste grain. Feeding on
wheat is of little economic importance, since most of that taken is
waste grain. Feeding on sunflower seeds may be counted as neutral to
slightly beneficial. Damage to watermelons, which are extensively grown
in the sandhills region, may be important at times. Crow feeding upon
other crops is only locally significant.
Although it has food preferences, the crow is euryphagous, and its diet
is governed to a large extent by the availability of various types of
food in its habitat. Therefore, in its ecologic relationships with many
other species, it is a density dependent predator. It reduces the
numbers of a certain species when the latter becomes unusually abundant
but lessens the mortality pressure against it when the prey population
is low. Predators of this type tend to maintain stability in a community
in contrast to the violent oscillations often caused by a more
stenophagous predator. This study indicates that in south-central Kansas
crows help to stabilize the populations of grasshoppers, ground-dwelling
beetles both predaceous and non-predaceous, and probably those of other
types of insects whose soil dwelling larvae are subject to predation
during summer plowing.
Crows also serve as scavengers, feeding on carrion and at dumping
grounds, as indicated by the high frequency of eggshell and mammalian
bone in the diet. Bird bones were found in an insignificant amount in
this study, but extensive collections were not made during the main
nesting season.
Summary
An intensive study of the yearly diet of crows was carried on from
December, 1952, to February, 1954, in Harvey County and the northeastern
townships of Reno County, Kansas, in order to discover some of the
ecologic and economic relationships of the population of crows in
south-central Kansas. The study is based upon the analysis of 617
regurgitated pellets collected throughout the year. Data obtained from
this analysis have been correlated with field observations on crows and
habitat changes.
The area is in the zone of transition between tall-grass and short-grass
prairie, and the predominant agricultural crop is wheat. The study area
supports a breeding population of approximately one pair of crows per
square mile, but large flocks of wintering crows move into the western
part of the area near the Arkansas River Valley.
Plant material amounted to 69.0 per cent of the pellet residues. Wheat
is the food taken in greatest amount in the yearly average, but the
staple foods of the wintering crows are grain sorghum, sunflower seeds,
and corn. Crows use newly sown oat fields as a major source of food in
late winter and early spring, but damage to the crop seems to be slight.
Growers of grain sorghum and, locally, growers of corn and watermelons,
sustain serious damage from crows.
Being euryphagous, crows exert a stabilizing influence on many kinds of
prey and on the biotic community as a whole. This study indicates that
their effects are especially important in helping to stabilize the
populations of grasshoppers and of ground-dwelling beetles, and possibly
those of some other insects that have soil-dwelling larvae.
Carrion and material from dumping grounds furnish another fairly
constant component of the crow's diet.
TABLE 1. AVERAGE, MAXIMUM, AND MINIMUM PERCENTAGES OF FOOD RESIDUES IN
PELLETS COLLECTED IN EASTERN HARVEY COUNTY, IN 1953.
[Transcriber's note: Table split in two]
| April | June |June 29-| July |July 27-| Aug. | Sept. |
| 6-19 | 15-28 |July 12 | 13-26 |Aug. 9 | 10-23 | 7-20 |
-------------+-------+-------+--------+-------+--------+-------+-------|
Number of | | | | | | | |
pellets | 9 | 7 | 6 | 19 | 18 | 5 | 57 |
-------------+-------+-------+--------+-------+--------+-------+-------|
No. of | | | | | | | |
Collections | 1 | 4 | 4 | 4 | 4 | 2 | 5 |
-------------+-------+-------+--------+-------+--------+-------+-------|
| 18.2 | 34.4 | 1.7 | 35.7 | 28.5 | 29.0 | 23.4 |
wheat | (90-5)|(99-50)| (10) |(80-10)| (80-5) |(55-20)|(100-5)|
-------------+-------+-------+--------+-------+--------+-------+-------|
| | | | | 2.0 | | 10.7 |
sorghum | | | | | (35) | |(90-10)|
-------------+-------+-------+--------+-------+--------+-------+-------|
| 72.6 | | | 1.6 | | | |
oats |(99-50)| | | (30) | | | |
-------------+-------+-------+--------+-------+--------+-------+-------|
sunflower | | | | | | | |
seed | | | | | | | |
-------------+-------+-------+--------+-------+--------+-------+-------|
| | | | | | | |
corn | | | | | | | |
-------------+-------+-------+--------+-------+--------+-------+-------|
| | | | .5 | 44.6 | 28.6 | 4.8 |
grass seed | | | | (5) | (90-60)| (85-5)| (70-5)|
-------------+-------+-------+--------+-------+--------+-------+-------|
| | | | | | | .1 |
grape | | | | | | | (2) |
-------------+-------+-------+--------+-------+--------+-------+-------|
| | 20.1 | 1.7 | | | | |
cherry | |(70-20)| (10) | | | | |
-------------+-------+-------+--------+-------+--------+-------+-------|
| | | .8 | .1 | | | |
spurge | | | (5) | (2) | | | |
-------------+-------+-------+--------+-------+--------+-------+-------|
| | | | 1.6 | 5.2 | | |
misc. plant | | | |(30-10)| (95) | | |
-------------+-------+-------+--------+-------+--------+-------+-------|
TOTAL PLANT | 90.8 | 54.5 | 4.2 | 39.5 | 80.3 | 57.6 | 39.0 |
-------------+-------+-------+--------+-------+--------+-------+-------|
scarabaeid | | 28.7 | 5.0 | | | | |
beetle | |(75-25)| (30) | | | | |
-------------+-------+-------+--------+-------+--------+-------+-------|
other | 2.7 | .1 | 34.2 | 48.7 | 10.0 | 21.0 | 19.0 |
beetle | (10-5)| (3) |(100-20)|(90-10)| (90-10)|(45-10)|(80-5) |
-------------+-------+-------+--------+-------+--------+-------+-------|
| | .1 | 6.6 | 10.9 | 4.2 | 15.0 | 23.4 |
grasshopper | | (2) |( 40) |(40-5) | (40-5) |(30-5) |(100-5)|
-------------+-------+-------+--------+-------+--------+-------+-------|
| | | | | | | 5.9 |
ant | | | | | | |(90-75)|
-------------+-------+-------+--------+-------+--------+-------+-------|
| | | | | | | 1.9 |
misc. insect | | | | .5 | | |(50-5) |
-------------+-------+-------+--------+-------+--------+-------+-------|
| .5 | 1.5 | 35.0 | | .6 | 1.0 | 1.2 |
crayfish | (5) | (10) |(100-10)| | (10) | (5) |(25-10)|
-------------+-------+-------+--------+-------+--------+-------+-------|
| | | | | .6 | | .6 |
snail | | | | | (10) | |(10-2) |
-------------+-------+-------+--------+-------+--------+-------+-------|
| | | | .1 | | .1 | 4.8 |
fish | | | | (7) | | (5) |(20-5) |
-------------+-------+-------+--------+-------+--------+-------+-------|
| | | 15 | | | | |
bird | | | (90) | | | | |
-------------+-------+-------+--------+-------+--------+-------+-------|
| | | | .3 | .6 | 3.0 | 2.0 |
eggshell | | | | (5) | (10) |(10-5) | (30-5)|
-------------+-------+-------+--------+-------+--------+-------+-------|
| 6 | 15.1 | | | 3.7 | 1.4 | 2.2 |
mammal |(45-10)|(100-5)| | | (50-5) | (5-2) | (60-2)|
-------------+-------+-------+--------+-------+--------+-------+-------|
TOTAL ANIMAL | 9.2 | 45.5 | 95.8 | 60.5 | 19.7 | 42.4 | 61.0 |
-----------------------------------------------------------------------|
|Sept. 21-| Oct. |Oct. 19-| Nov. | Nov. |Nov. 30-
|Oct. 4 | 5-18 |Nov. 1 | 2-15 | 16-29 |Dec. 13
-------------+---------+-------+--------+--------+-------+--------
Number of | | | | | |
pellets | 29 | 27 | 24 | 25 | 7 | 8
-------------+---------+-------+--------+--------+-------+--------
No. of | | | | | |
Collections | 4 | 4 | 3 | 5 | 1 | 2
-------------+---------+-------+--------+--------+-------+--------
| 21.5 | 10.8 | 35.4 | 33.0 | 43.7 | 49.1
wheat |(100-5) |(60-15)|(85-10) | (80-35)|(98-30)|(98-20)
-------------+---------+-------+--------+--------+-------+--------
| 14.0 | 7.6 | 24.4 | 24.7 | 28.6 | 6.9
sorghum | (75-5) | (60-3)| (85-5) |(100-10)| (80-5)|(40-15)
-------------+---------+-------+--------+--------+-------+--------
| | | | | |
oats | | | | | |
-------------+---------+-------+--------+--------+-------+--------
sunflower | | | | | 6.4 |
seed | | | | | (40-5)|
-------------+---------+-------+--------+--------+-------+--------
| | | 4.5 | 4.0 | 1.4 | 15.0
corn | | | (50-10)| (80-10)| (10) |(70-50)
-------------+---------+-------+--------+--------+-------+--------
| | | | | |
grass seed | | | | | |
-------------+---------+-------+--------+--------+-------+--------
| | | | | |
grape | | | | | |
-------------+---------+-------+--------+--------+-------+--------
| | | | | |
cherry | | | | | |
-------------+---------+-------+--------+--------+-------+--------
| | | .2 | | |
spurge | | | (5) | | |
-------------+---------+-------+--------+--------+-------+--------
| 4.4 | 1.6 | 2.1 | 5.5 | 2.9 | 14.3
misc. plant | (90-40) | (45) | (50) | (75-10)| (20) |(70-45)
-------------+---------+-------+--------+--------+-------+--------
TOTAL PLANT | 39.9 | 20.0 | 66.6 | 67.2 | 83.0 | 85.3
-------------+---------+-------+--------+--------+-------+--------
scarabaeid | | | | | |
beetle | | | | | |
-------------+---------+-------+--------+--------+-------+--------
other | 10.6 | 15.5 | 13.9 | 14.4 | 5.3 | 2.5
beetle | (95-5) |(98-1) | (70-5) | (65-5) | (15-2)| (20)
-------------+---------+-------+--------+--------+-------+--------
| 36.3 | 59.6 | 11.8 | 14.3 | 10.3 | 4.4
grasshopper | (95-5) |(90-34)| (65-5) | (99-5) | (65-2)|(10-5)
-------------+---------+-------+--------+--------+-------+--------
| | | | | |
ant | | | | | |
-------------+---------+-------+--------+--------+-------+--------
| 2.8 | | | | |
misc. insect | (60) | | | | |
-------------+---------+-------+--------+--------+-------+--------
| .2 | .4 | 1.4 | | |
crayfish | (5-2) | (5-2) | (20-10)| | |
-------------+---------+-------+--------+--------+-------+--------
| 1.3 | trace | 1.1 | .2 | |
snail | (20-5) | (1) | (10-5) | (5) | |
-------------+---------+-------+--------+--------+-------+--------
| 7.3 | 2.5 | 3.4 | .6 | |
fish | (20.5) |(20.1) | (20-5) | (10-5) | |
-------------+---------+-------+--------+--------+-------+--------
| | | | | |
bird | | | | | |
-------------+---------+-------+--------+--------+-------+--------
| 1.1 | .4 | .2 | .8 | .7 |
eggshell | (10-5) | (1) | (5) | (20) | (5) |
-------------+---------+-------+--------+--------+-------+--------
| .5 | 1.6 | 1.6 | 2.5 | .7 | 7.8
mammal | (5) | (20-2)| (10-5) | (20-1) | (5) |(25-2)
-------------+---------+-------+--------+--------+-------+--------
TOTAL ANIMAL | 60.1 | 80.0 | 33.4 | 32.8 | 17.0 | 14.7
------------------------------------------------------------------
TABLE 2. FREQUENCIES OF OCCURRENCE OF FOOD RESIDUES IN PELLETS COLLECTED
IN THE EASTERN PART OF HARVEY COUNTY--1953.
===============================================================================
|April 6-19
| |June 15-28
| | |June 29-July 12
| | | |July 13-26
| | | | |July 27-Aug. 9
| | | | | |Aug. 10-23
| | | | | | |Sept. 7-20
| | | | | | | |Sept. 21-Oct. 4
| | | | | | | | |Oct. 5-18
| | | | | | | | | |Oct. 19-Nov. 1
| | | | | | | | | | |Nov. 2-15
| | | | | | | | | | | |Nov. 16-29
| | | | | | | | | | | | |Nov. 30-Dec. 13
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
No. of pellets | 9 | 7 | 6 | 19| 18| 5 | 57| 29| 27| 24| 25| 7 | 8
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
wheat | 6 | 3 | 1 | 18| 16| 4 | 27| 12| 10| 15| 13| 4 | 6
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
sorghum | | | | | 1| | 20| 12| 10| 12| 12| 4 | 2
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
sunflower seed | | | | | | | | | | | | 2 |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
oats | 8 | | | 1| | | | | | | | |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
brome grass | | | | 2| 10| 4 | | | | | | |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
corn | | | | | | | | | | 3| 3| 1 | 2
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
cherry | | 3 | 1 | | | | | | | | | |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
grass seed | | | | | | | 11| | | | | |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
spurge | | | 1 | 1| | | | | | 1| | |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
grape | | | | | | | 1| | | | | |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
misc. plant | | | | 2| 1| | | 2| 1| 1| 3| 1 | 2
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
beetle | | | | | | | | | | | | |
(scarabaeid) | | 4 | 1 | | | | | | | | | |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
beetle (other) | 4 | 1 | 4 | 19| 5| 5 | 39| 15| 17| 16| 14| 4 | 1
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
grasshopper | | 1 | 1 | 12| 6| 5 | 39| 22| 24| 12| 18| 3 | 6
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
ant | | | | | | | 4| | | | | |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
bug | | | | | | | | | | | | |
(hemipteran) | | | | 1| | | | | | | | |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
misc. insect | | | | | | | 3| 1| | | | |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
crayfish | 1 | 1 | 3 | | 1| 1 | 3| 2| 2| 2| | |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
snail | | | | | 1| | 7| 4| 1| 4| 1| |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
fish | | | | 2| | 1 | 28| 14| 7| 7| 2| |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
bird | | | 1 | | | | | | | | | |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
eggshell | | | | 1| 1| 2 | 10| 5| 8| 1| 1| 1 |
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
mammal | 2 | 2 | | | 4| 2 | 8| 3| 5| 5| 8| 1 | 5
---------------+---+---+---+---+---+---+---+---+---+---+---+---+---------------
TABLE 3. AVERAGE, MAXIMUM, AND MINIMUM PERCENTAGES OF FOOD RESIDUES IN
PELLETS COLLECTED AT WINTERING CROW ROOSTS IN THE WESTERN PART OF THE
STUDY AREA--1952-53-54.
|Dec. 28-Jan. 11
| |Aug. 24-Sept. 6
| | |Sept. 7-20
| | | |Oct. 5-18
| | | | |Nov. 16-29
| | | | | |Dec. 14-27
| | | | | | |Dec. 28-Jan. 10
| | | | | | | |Feb. 8-21
===============================================================================
Number of| | | | | | | |
pellets | 62 | 5 | 38 | 65 | 56 | 22 | 96 | 32
---------+--------+-------+-------+--------+-------+--------+--------+---------
No. of | | | | | | | |
Collec- | | | | | | | |
tions | 1 | 1 | 1 | 1 | 3 | 1 | 1 | 1
---------+--------+-------+--------+-------+-------+--------+--------+---------
| 6.9 | 62.8 | 14.6 | 22.7 | 2.2 | | 3.3 | 2.8
wheat |(100-10)|(99-35)|(90-10)|(90-10) |(95-10)| |(90-30) |(50-10)
---------+--------+-------+-------+--------+-------+--------+--------+---------
| 29 | 1 | 22.4 | 31.2 | 41.2 | 42.5 | 32.4 | 21.6
sorghum |(100-5) | (5) |(95-5) |(100-10)|(100-5)|(100-5) |(100-10)|(100-10)
---------+--------+-------+-------+--------+-------+--------+--------+---------
sunflower| 26.3 | | 3.3 | 5.0 | 26.9 | 22.0 | 32.4 | 21.6
seed | (90-5) | | (95-5)| (60-10)| (95-3)| (90-5) |(100-5) |(80-10)
---------+--------+-------+-------+--------+-------+--------+--------+---------
| 11.4 | 19.0 | 12.4 | 4.5 | 14.0 | 11.4 | 14.1 | 1.2
corn |(100-10)|(40-15)| (95-5)| (85-30)|(100-5)|(100-10)|(100-5) |(20-10)
---------+--------+-------+-------+--------+-------+--------+--------+---------
| 14.1 | | | 4.9 | 5.7 | 5.5 | 4.6 | 37.2
oats |(100-10)| | | (80-15)| (70-5)| (75-5) | (95-5) |(100-10)
---------+--------+-------+-------+--------+-------+--------+--------+---------
brome | 1.4 | | | | | | .1 |
grass | (85) | | | | | | (10) |
---------+--------+-------+-------+--------+-------+--------+--------+---------
Other | 9.4 | | | 3.2 | 4.0 | 15.7 | 8.8 | 6.3
Grass | (95-5) | | | (80-20)|(90-10)| (95-10)|(100-10)|(50-20)
---------+--------+-------+-------+--------+-------+--------+--------+---------
| | | trace | | | | .1 |
grape | | | (2) | | | | (10) |
---------+--------+-------+-------+--------+-------+--------+--------+---------
| | | .4 | .5 | | | |
pokeberry| | | (15) | (30-2) | | | |
---------+--------+-------+-------+--------+-------+--------+--------+---------
| | | | .4 | | | .2 |
spurge | | | | (25) | | | (10-1) |
---------+--------+-------+-------+--------+-------+--------+--------+---------
| | | | | .1 | | .5 | .2
ragweed | | | | | (5) | | (10-5) | (5)
---------+--------+-------+-------+--------+-------+--------+--------+---------
misc. | 1 | | .8 | | | | .8 | .2
plant | (50-1) | | (30) | | | | (80-2) | (3-2)
---------+--------+-------+-------+--------+-------+--------+--------+---------
TOTAL | | | | | | | |
PLANT | 99.5 | 82.8 | 53.9 | 72.4 | 94.1 | 97.1 | 97.4 | 97.4
---------+--------+-------+-------+--------+-------+--------+--------+---------
grass- | .1 | 6.0 | 8.9 | 10.5 | 1.4 | | .5 | .3
hopper | (5) | (30) | (30-5)| (70-5) |(15-5) | | (15-5) | (5)
---------+--------+-------+-------+--------+-------+--------+--------+---------
| .1 | 9 | 17.8 | 12.1 | 1.7 | .9 | .4 | .9
beetle | (5) |(15-10)| (95-2)| (80-3) |(15-2) | (10-5) | (10-5) | (10-5)
---------+--------+-------+-------+--------+-------+--------+--------+---------
| | | 14.9 | 3.4 | | | |
ant | | |(95-73)| (85-5) | | | |
---------+--------+-------+-------+--------+-------+--------+--------+---------
| | | .7 | .8 | | | .5 |
crayfish | | |(10-5) | (50) | | | (50) |
---------+--------+-------+-------+--------+-------+--------+--------+---------
| .1 | | | | .1 | | .1 |
snail | (5) | | | | (5) | | (5) |
---------+--------+-------+-------+--------+-------+--------+--------+---------
| | | .1 | | | | .1 |
fish | | | (5) | | | | (5) |
---------+--------+-------+-------+--------+-------+--------+--------+---------
| | | 1.8 | | | .9 | |
snake | | |(60-5) | | | (20) | |
---------+--------+-------+-------+--------+-------+--------+--------+---------
| | | | | .3 | .4 | .6 | 1.1
eggshell | | | | |(10-5) | (10) | (10-5) | (20-5)
---------+--------+-------+-------+--------+-------+--------+--------+---------
| 2 | 2.2 | 1.9 | .8 | 2.4 | .7 | .4 | .3
mammal | (10-5) | (5-1) |(20-5) | (10-5) |(60-5) | (10-5) | (10-5) | (10)
---------+--------+-------+-------+--------+-------+--------+--------+---------
TOTAL | | | | | | | |
ANIMAL | .5 | 17.2 | 46.1 | 27.6 | 5.9 | 2.9 | 2.6 | 2.6
-------------------------------------------------------------------------------
TABLE 4. FREQUENCIES OF OCCURRENCE OF FOOD RESIDUES IN PELLETS COLLECTED
AT WINTERING CROW ROOSTS IN THE WESTERN PART OF THE STUDY
AREA--1952-53-54.
===================+====================================================
| Dec. 28-Jan. 11
| +-----------------
| | Aug. 24-Sept. 6
| | +-----------
| | | Sept. 7-20
| | | +----------
| | | | Oct. 5-18
| | | | +-----------
| | | | | Nov. 16-29
| | | | | +-----------
| | | | | | Dec. 14-27
| | | | | | +----------------
| | | | | | | Dec. 28-Jan. 10
| | | | | | | +----------
| | | | | | | | Feb. 8-21
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
Number of pellets | 62 | 5 | 38 | 65 | 56 | 22 | 96 | 32 |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
wheat | 11 | 5 | 10 | 27 | 3 | | 5 | 4 |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
sorghum | 45 | 1 | 22 | 36 | 44 | 16 | 74 | 18 |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
sunflower seed | 43 | | 5 | 12 | 32 | 9 | 68 | 19 |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
corn | 14 | 4 | 11 | 5 | 12 | 8 | 27 | 3 |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
oats | 18 | | | 8 | 9 | 3 | 12 | 24 |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
brome grass | 1 | | | | | | 1 | |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
other grass | 15 | | | 5 | 5 | 7 | 15 | 5 |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
grape | | | 1 | | | | 1 | |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
pokeberry | | | 1 | 2 | | | | |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
spurge | | | | 1 | | | 5 | |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
ragweed | | | | | 1 | | 8 | 1 |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
misc. plant | 4 | | 1 | | | | 2 | 2 |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
grasshopper | 1 | 1 | 23 | 38 | 10 | | 5 | 2 |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
beetle | 1 | 4 | 38 | 48 | 15 | 3 | 6 | 4 |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
ant | | | 7 | 6 | | | | |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
crayfish | | | 3 | 1 | | | 1 | |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
snail | 1 | | | | 1 | | 1 | |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
fish | | | 1 | | | | 1 | |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
snake | | | 2 | | | 1 | | |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
eggshell | | | | | 2 | 1 | 9 | 3 |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
mammal | 2 | 3 | 5 | 7 | 10 | 2 | 5 | 1 |
-------------------+-----+-----+-----+-----+-----+-----+-----+-----+
Literature Cited
ALDOUS, S. E.
1944. Winter habits of crows in Oklahoma. Jour. Wildlife Management,
8:290-295, 1 fig.
ALEXANDER, F. M.
1930. Notes on the birds of south-central Kansas. Wilson Bull.,
42:241-244.
BARROWS, W. B., and SCHWARZ, E. A.
1895. The common crow of the United States. U. S. Dept. of Agric. Div.
Ornith. and Mammal., 6:1-98, 2 figs.
BLACK, C. T.
1941. Ecological and economic relations of the crow with special
reference to Illinois. Unpublished thesis, Univ. of Illinois, Urbana,
Illinois.
HAYES, W. P.
1918. Studies on the life history of two Kansas Scarabaeidae. Jour.
Econ. Entom., 11:136-144.
1920. The life histories of some Kansas Lachnosterna. Jour. Econ.
Entom., 12:109-117.
HERING, P. E.
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_Transmitted November 9, 1955._
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