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United States Department of Agriculture
Eureau of Biological Survey

lildlife Research and Management Leaflet BS-96

Washington, D. C. * November 1937 |

BLACKBIRDS AND THE RICE CROP ON TF2 GULF COAST

By E. Re KATMBACH, Senior Biologist
Section of Food Habits, Division of’ Wildlife Research

Contents
“Page Page
Introduction. 6 saree: ER ein ie, «6 alt Control by snooting a) eCerea a, 4
Mirae CtCK ss » tne «.5 8 it Barly Prolific rice escapes
Varied extent of damage... 2 GAMA SO. <aye ve cok eee Se ee
Memidiomine flocs. is « » « 6 2 Karly seeding of Blue Rose not
Legal status of blackbirds. . 2 AdvisabLe..c« si <4 <2 see ee
ntroduction

Blackbirds have been a source of trouble to rice growers of the Gulf
Coast of Louisiana and Texas ever since that grain was introduced into the
soutnern prairie region. Damage is inflicted in spring, when the sprouting
grain attracts the birds; in midsummer, when the crop is in the "milk" or
"dough" stage; and at harvest, wnen the shocked grain may be attacked not only
by the resident red—-winged blackbirds, the principal offenders, but also by
the larger boat-tailed grackles, or "jackdaws", and, if the crop is late,
by migratory blackbirds from northern States.

Area Affected

Some years ago a thorough study was made of this problem, particularly
to learn what measures could be adopted to lessen the annual losses. The
survey revealed interesting facts. In the first place, the area of severe

is a narrow one, being the southern edge of the rice district that borders on
the extensive marshes lying along the Gulf const. In some instances this zone
of severe damage may comprise a single tier of fields adjacent to the marsh.
Three or four miles from the borderline severe damage is of irregular oc-
currence, depending largely on the presence of trees or sloughs that attract
the birds. In the central and northern parts of the rice belt, where the land
has been longer under cultivation, and where most marshy areas attractive to
blackbirds have been drained, noticeable damage to the rice crop is seldom
experienced. Control measures thus are only locally required.

Varied Extent of Damage

Wot only ig the zone of severe blackbird damage narrow, but from
year to year there may be great fluctuations in its extent and severity.
Rains during the sprouting season tend to increase the damage by malzing the
ground soft and easily probed by birds. A harvest delayed by inclement
weather exposes the shocked crop to attacks not only of the resident black—
birds but also of migrants that arrive from the north in October and
November. Such climatic conditions as the prolonged drought that occurred
during the latter part of 1924 and the early part of 1925 also affect the
activities of the birds, causing then to avoid vast areas of burned-over
marsh that normally support a large breeding vopulation.

In 1924, tests made by a rice-growing company in Louisiana indicated
a crop loss as great as 22 percent on certain fields close to the virgin marsh.
In the following year similar tests, many of which were carried out in the
same fields, disclosed no appreciable damage. For the entire rice~growing
area of Louisiana, including the zone of severe damage as well as the great
acreage in which injury is infrequent, the average annual loss to the rice crop
caused by blackbirds probably does not exceed 1 percent of the yield. Although
such an estimate might appear to minimize the importance of the problem, it
must not be overlooked that the great bulk of the damage occurs in a limited
area and that in this area rice growers suffer severe losses. It was to remedy
conditions in such sections that experiments in blackbird control were con-
ducted.

Wandering Flocks

lackbirds are nomads. Daily they make trips to and from their feeding
grounds in the rice fields and their roosts in the marshes. Sometimes the
flocks number tens of thousands. With widely available food the birds may be
in a certain locality one day and miles away the next. At times, however, they
persist in levying toll on particular fields and may be found day after day in
the same section. Suddenly they may leave and, like a tornado, strike at
some distant point. Unlike field mice, ground squirrels, or other rodent
pests that are to be found not far from their runways or burrows, the presence
of blackbird flocks cannot be predicted with certainty. This is especially
true during the period of ripening grain and at harvest, when there is food
to be had everywnere. Even during the planting season, when the natural food
supply is at its lowest ebb and the newly seeded rice fields are the principal
attraction to the birds, their uncertain wanderings prevent the carrying out
of consistently successful control measures.

Legal Status of Blackbirds

On June 20, 1936, the President approved an act, 49 Stat. 1555, amend—
ing the Migratory Bird Treaty Act of July 3, 1918, to afford protection to
additional migratory birds by extending its provisions to the treaty between
the United States and the United Mexican States, which was signed on February
7, 1936, and ratified on March 15, 1937. Among the birds thus given protection
are those of the family Icteridae, including orioles, meadowlarks, and black—
birds. ,

wees

As blackbirds at times become seriously injurious to agricultural crops,
however, the Secretary of Agriculture, by virtue of authority conferred upon
him by the afore-mentioned legislation, issued, under date of June 26, 1937,
an order permitting the shooting of certain species when found committing or
about to commit such depredations. Among the species of blackbirds mentioned
in the order is the redwing, which is the chief offender in the rice fields
along the Gulf coast.- Under the provisions of the order, the owner or
custodian of any agricultural crop may kill these birds by shooting only,
"but not by means of any gun to which a silencer or any other like device
has been attached or otherwise affixed, nor from any blind, sink, pit, or any
other device or means of concealment, whether natural or artificial." The
birds killed pursuant to this order may not be "shipped or transported or
sold or offered for sale except that they may be transported to such place
within the vicinity as may be necessary to. bury or otherwise destroy their
carcasses." Any person killing birds under the provisions of this order
must submit, on or before January 1 of each year, to the Chief, Bureau of
Biological Survey, U. S. Department of Agriculture, Washington, D- Ce, a re-
port of his operations.

Control by Shooting

Unless special authorization for other means of control is granted by
the Secretary of Agriculture, shooting is the only aggressive method available
to the rice growers in the zone of severe damage. By the more philosophical,
the expense of this means of control is considered an annual item necessary
for successful production of the crop and it is provided for with as much
certainty as any other element of crop production. The large rice-—growing
Companies advance ammunition to their tenant farmers just as they do seed and
fertilizer. Cheap black—powder shells and 1le-gage, double-barreled or re-
peating shotguns are used almost exclusively in this patrol work.

An idea of the efficiency of shooting as a means of crop protection
may be gained from the experience of a farmer living 4 miles southeast of
Gueydan, La. In one year he shot 4,500 shells costing $135. This expense,
with the labor involved in patrolling, was necessary to protect 230 acres that
yielded 2,600 sacks of rice. Judging from previous experience, this farmer
estimated that his crop would not have exceeded 1,000 sacks had the fields not
been patrolled. This indicates an expected loss of 1,600 sacks. Assuming
that his estimate was approximately correct, it would follow that his ex
penditure of $135 for ammunition, $35 for a gun that was burned out, and an
unstated amount for labor--possibly a total of $250--resulted in the saving,
at prices current at the time, of rice worth more than $7,800. Stated
differently, the cost of protection, which was fairly adequate, represented an
outlay equal to about 2 percent of the value of the entire crop.

In large fields distant from human habitations and livestock a rifle
may be used in place of the shotgun with increased economy and efficiency.
This procedure, by no means new to rice growers in California, has been
neglected in the rice fields of the Gulf coast.

For safety and convenience in reaching all parts of the field, a shoot-—
ing tower 15 to 20 feet high, built of scantlings, should be erected near the

2H

center of the area to be protented. Frem this vantage the bird minder can

see where he is shooting end direct his shots downward into the water or soft
mud of the rice field where they will do no further harm. By using 22-

caliber, long-rifle cartridges in place of the shotgun ammunition, this

element of cost can be reduced to about one-fifth. The longer range of the
rifle enables a person to patrol a larger area, and thus the cost of labor is
reduced to about one-fourth of that ordinarily expended when the shotgun is used.
Furthermore, tlackbirds respond more reacily to the impact of a rifle ball

than to bird shot and are more inclined to leave the fields after a shot or two.
In actual practice flocks of blackbirds numbering into the hundreds have been
eriven Grom stands of rice at distances jot 600) yards. By this onecedumes mated
minding is changed from an exhausting, nerve-racking, and often hopeless oc-
cupation to one that under some conditions might be considered leisurely and
comfortable. It must be emphasized, however, that rifle fire can be resorted
to safely only in areas of large fields away from human habitations and live-—
stock grazing.

Ovservations of the movements and habits of the redwings of southern
Louisiana disclosed that no flocks large enough to inflict serious damage
appear before the first of September. At that time of year all the Early
Prolific rice has passed beyond the milk and dough stages and, in fact, most
of it has been shocked. In some years even the threshing and hauling of this
strain of rice to the mills is well under way early in August. It 1s evadenp,
therefore, that this part of the rice crop or any other equally early strain
Will escape serious blackbird damage when in the milk and dough stages.
Because of this 4% would seem, other things being equal, to be an advantage to
sow only early-maturing rice in those fields that have been found particular—
ly susceptible to blackbird attack, Offsetting somewhat the adventage thus
gained, however, the early-maturing strains that ripen before the large flocks
of redwings have congregated also have an early planting period that invites
damage at sowing and sprouting time.

Harly Seeding of Blue Rose not Advisable

Despite advice to the contrary based on experimental work at the Crowley
(La.) Rice Experiment Station of the U. §. Department of Agriculture and State
Agricultural Experiment Station, many planters of the Gulf coast section begin
sowing even the late-maturing Blue Rose variety so early that not only do low
temperatures and cold rains frequently cause the seed to rot, but the early
sprouts are also exposed to the attacks of the droves of blackbirds not yet
scattered for the nesting season. Extensive cxperiments have demonstrated that
little is gained culturally by seeding the late-maturing Blue Rose as early as
February or March, and to do so invites early-season damage by blackbirds. ‘The
rice grower in the zone of blackbird damage confronted with possible serious
injury to sprouting rice sown in February and March, or even early in April, and
to the crop in the milk and dough stages late in Ausust and early in September
Cannot escape both possibilities by crop handling of varieties that nave a grow—
ing period of about 140 days. He can, however, avoid much of this trouble by
seeding his main crop of Blue Rose after the middle of April, and at the same
time he will be at no greater disadvantage at harvest time.

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