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United States Department of Agriculture
Bureau of Biological Survey

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Wildlife Research and Management Leaflet BS-64

Washington, D. C. iF September 1936.

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PROTECTING CROPS FROM DAMAGE BY HORNED LARKS IN CALIFORNIA

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By Johnson A. Neff, Assistant Biologist, Section of Food Habits
Division of Wildlife Research

Contents
Page $ Page

Pmt rEOGUctONe sts.) . os «a. « LL & Methods of prevention——Continued.
CmOMSmGananeas a a 6 ws le «+6 eine Attracting yvaltures!| = « « se)
Neiuic@nmsdemase. 6 5 « 6 = « 3 :. Scarecrows 6
Heasonron emacs: 0... MRE paner sonfetti 6
NeMCemus Od Gamage. 9. WM, 6 « eee es Paners on the ground .... =. 6
Gontrol methods . - . . . setts ors Stakes and flags... . 5 6
Methods of preventing damage. . Sar Continuous string Pisa tad 1h

Noise-making devices. -« ...- 5: Estimate of costs of continous .

Shooting or herding-off .. 5 string flagging. »« « « +». « « g

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Introduction

In certain parts of bald foenta the horned lark has become a serious
crop destroyer. The damage occurs mostly in the interior valleys from
Sacramento south to the Imperial Valley, and along the coastal strip from
San Francisco south to San Diego. The race of lark involved throughout most
of the area is the California horned lark (Otocoris alpestris actia). There
are a few recorded instances’ near oS ea c of damage by the ruddy horned
lark (Otocoris alvestris rubea). Certain attacks in the Mojave Desert region,
the Imperial Valley, and other desert valleys in southeastern California were
probably committed by other and as yet undetermined subspecies.

A bird fond of deserts, prairies, end fallow fields, in general, the
horned lark ranges from the snow line to sandy beaches, wherever there is
open country. After wintering in great numbers on the valley floors, most of
these birds leave the farming sections early in spring and migrate into the
foothills or into the dry grasslands and desert. Here the season of nesting
and rearing the young is spent.

There is a moderately constant population of horned larks resident in
stubble, grass, and fallow fields in the cropped area, but the mass of the
birds live in the wide expanses of the deserts, rolling mesas, foothills,

and dry grasslands that encircle the farming areas. During May and June the
young of resident horned larks may be noted about the fields. Beginning
usually late in June or early in July, when the early broods of youngsters

are just able to travel extensively, there is a movement from the open country
into the general farming district, and the population of horned larks in the
latter areas may show a sudden and great increase. Further increases in num-
bers may be noted throughout the remainder of the summer and early fall, as
additional bands flock in from their open-country range.

"The food of the horned lark consists largely of seeds picked up from
the ground." This statement by Beal is virtually as true today as it was
when Beal wrote it in 1910, a Analysis of the food items contained in 259
horned lark stomachs collected in California showed the annual food of the
birds to consist of about 91 percent vegetable, and 9 percent animal, matter.
Among the vegetable foods Beal listed corn, wheat, and oats from among the
cultivated crops. Seeds of weeds and wild grasses averaged 51 percent of the
total food. Insects were largely taken from March to June, and many of them
were fed the young.

Study of a small series of stomachs recently collected reveals little
change except that the birds! liking for succulent vegetable crops, practi-
cally unknown in Beal's time, has accentuated their vegetarian preferences.
In much of the State the item most frequently found in the stomachs of horned
larks is the seed of red maids (Calandrinia caulescens menziesii), maich
Sa in profusion over a wide area. Other seeds commonly found are those of

martweed (Polygonum), alfilaria (Eredium), rye grass (Lolium), spurrey
(cca. campion (Silene), and tarweed (Hemizonia), When available, wheat,
barley, oats, and milo maize may be taken from newly seeded grainfields. or
from stubble. Insect food during the period of crop damage is unimportant.

Crops Damaged

Horned larks are given great opportunity for damage by the widespread
abundance of cultivated products attractive to them. In the irrigated valleys
almost all kinds of green table vegetables are raised, large acreages of vege~
tables and sugar beets are grown for seed, and beans cultivated for the dried
product. In these valleys also are great flower~seed producing areas. On the
lower hills and unirrigated rolling lands additional thousands of acres of
similar crops adapted to dry-farming are grown. Production continues some-
where in.the State throughout the year.

Among the vegetable crops severely damaged by horned larks are lettuce,
carrots, beets, spinach, turnips, and peas. Plantlets of field and truck
crops destroyed include those of black-eyed peas, beans of nearly every type,
sugar beets, cantaloupes, water melons, and tomatoes. Flower plantlets of
many varieties, in commercial seed plantings, are frequently devoured.

ee ee es et

aly Birds of California in Relation to the Fruit Industry, part 2,
by F. E. L. Beal. Biological Survey Bulletin No. 34.

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‘Nature of Damage

Damaze by horned larks usually begins as the first plants break
through the surface of the soil, and it may continue until the plants reach
a height of several inches. The horned lark nips off parts of the tender
plantlets, or in the case of small, weak-rooted seedlings such as lettuce,
it may pull up the entire plant. In any event, if nipped off below the
erowm, the plantlet dies. In more robust kinds, such as beans, the first
cotyledons may be nipped off, the plant being thus destroyed. If the seed-
ling is not destroyed in any early stage, secondary leaflets and adventitious
buds are speedily consumed as they appear. They are often pruned back so
persistently that the plants are permanently dwarfed and as a result produce
no fruit or seed.

Although the most severe attacks are usually upon tender plantlets,
in certain years extensive depredations have occurred upon bean and pea blos-
soms late in the summer. This may be so serious as virtually to wipe out
the crop in an entire district. In a few instances horned larks have been
observed picking the outer leaves of head lettuce to such depth that exces-
sive waste was occasioned in discarding the perforated leaves. In one case
it was noted that as turnip seedlings appeared through the ground the birds
literally dug up the drill-track to feed upon the germinating seeds.

Laboratory analysis of the stomach contents of horned larks engaged in
these attacks usually fails to give an accurate idea of the damage done.
A certain quantity of the green vegetable tissue will be found in the stomachs
of the birds; yet in many instances it is noted that by far the major portion
of the plant tissue torn from the plantlets is dropped on the ground; further-
more, many plantlets may. be pulled up or broken off and left without any
evidence of the removal of any of the leaflets. Probably depredations upon
green crop plants result from a search for moisture. ;

On dry-farmed areas, where plant growth is slow, the damage may extend
over a long period and thus cause excessive loss. In irrigated fields, where,
the plants grow rapidly, the attack is usually of relatively short duration.
On the other hand, irrigation of fields in an otherwise arid area and without
green vegetation may cause an abnormal concentration of birds, resulting in
severe losses.

The first evidence of damage by horned larks is usually the.denuding of
Fiants from a small-arca near the center of a field, distant from cover or
fences. As the attack continues the bare spot may spread with startling
rapidity, until in severe depredations only a narrow fringeof undamaged plants
may remain about the borders of the field.

Season of Damage

In general, attacks by horned larks upon crops are closely correlated
with the dry season. Most of the depredations occur after the natural vege-
tation of the surrounding range or grassland has dried up, and they may
continue until the first fall rains come. Because of the great variation
in conditions within the State, one can say only that the greater part of
the damage occurs bétween mid-June and November.

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Several periods of subnormal rainfall have brought increased damaze
to crops by these birds, apparently because of scarcity in their natural
habitats of vegetative growth necessary for food. In contrast, in the winter
of 1934-35 an abnormally heavy rainfell occurred over the entire State, and
during the summer of 1935 damage by horned larks averaged less than 20 percent
of that inflicted during the preeedsns five-year period.

Donecda tone cannot be entirely blamed on aridity, however, for sporadic
attacks occur even during midwinter after heavy rainfall. Damage is noted
also on slopes immediately above the ocean where moisture always is present.
Moreover, these birds exhibit at times a marked propensity to continue feed-
ing upon certain fields once ‘they have acquired a taste for the succulent
young plants, even though an abundance of natural food may be available in
closely adjacent areas.

In many districts it has been necessary to modify cropping methods
to guard against the attack of the larks. In certain areas crops especially
sought. by them are no-longer planted; summer—growing crops are, if possible,
planted in May in order that the plants may be large enough to escape the
attack that begins late in June; and maDene rowing crops are often not sown
until after the first rains in the fall: even then, a prolonged fall -drought
frequently occasions a severe bird attack.

Severity of Damage

the severity of attack naturally varies with seasonal and topographic
circumstances, crop production methods, availability of natural foods, and
with the density of the horned lark population. It must also be considered
in computing economic losses that some of the crops attacked require an es-
pecially fertile, hence high-priced, soil. ‘The cost of preparing the soil
for seeding often is increased by specialized methods demanded, and irriga~
tion and cultural methods add to the overhead, making the culture of some of
these crops a costly undertaking. Losses are therefore Keeny edstrs

Innumerable records of estimated losses from depredations and costs
of control operations are available, from which only a few illustrative exam-
ples are noted. In 1927, near Murray, in Kings County, a packing company
planted 40 acres of spinach. Just as the plants began to emerge from the soil
@ concentration of horned larks destroyed approximately 34 acres of the erop 3
within a 48-hour period. In 1932 the same company planted 240 acres of spinach
in the same vicinity. Costs of $2,000 were incurred in labor and ammunition
in an effort to protect the-crop, yet fully 40 acres were totally destroyed.
No spinach has been planted in that area since 1932.

In 1933 severe losses were suffered in Riverside County in plantings
of sugar beets for seed. American production of this seed is an infant
industry, and the damage in retarding its development here was. far greater
than the cash appraisal of actual losses in time and material. .

In 1934, in San Luis Obispo County an agricultural official estimated
that fully 500 acres of beans and lettuce were destroyed. During the same
period there was reported from Santa Barbara County the loss of well over

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1,000 acres of beans in the Santa Maria district alone; the writer person-
ally inspected several ranches wheré fields as large as 200 acres were totally
destroyed. During the same season, agricultural officials estimated that
fully 1,500-acres of crops were destroyed in Monterey County. Numerous other
instances are cited in "The Need for Studies in Bird Control in California,"
by W. L. McAtee,2 and there are scores of other such reports in unpublished
notes.

Control Methods

Methods that involve the killing of the horned larks are not discussed
in this leaflet. Although such methods have been partially developed, their
application is so involved with climatic, topographic, and ecologic conditions
that it is not advisable to discuss them here; nor is it practicable to
depend on them for crop protection except under occasional favorable local
conditions. Their use is not recommended unless under trained supervision.

Methods of Preventing Damage

The development of effective methods of preventing attack by horned
larks has been progressive, limited only by the ingenuity of the persons
concerned. It is the purpose of this leaflet to discuss briefly the various
methods that have been seen in actual use and to comment upon their effec-
tiveness.

Noise-making Devices.--Sometimes one may see one or more men slowly
patrolling a field in which crop damage is occurring id beating energeti-
cally and constantly upon tin pans or cans. This method is commonly prac=
tised only where low-waged foreign labor is employed, and effective crop
protection by its use demands so large a number of men for any sizable plant-
ing that it immediately becomes uneconomical and impractical. In any case,
if too few men are used, the bands of horned larks drift along ahead or
alight in another part of the field where they continue their feeding.

Shooting or Herdineoff.--Herdins off with guns has proved too costly
in labor and ammunition, and is generally inefficient and impracticable. The
horned larks keep just out of gun shot, and because of their groundlike color
they are difficult to see at any distance. The Kings County packing company's
planting of spinach in 1932, already mentioned, was patrolled by 24 men, one
to each 10 acres, at a cost of $1,300 for labor and $700 for ammunition, yet
&@ Sixth of the planting was a total loss. Although some exceptions may be
noted, this is a fair example of the futility of the herding method.

Attracting Vultures.--In some sections the rancher obtains all the
available heads of slaughtered cattle from the community slaughter house,
mounts them upon short poles, and places them at intervals over the field.
Some farmers collect all the available white chickens in the vicinity, kill
them, and scatter the dead bodies at intervals over the field. Both these

Os a ee ee ee ee

2/ California State Department of Agriculture, Monthly Bulletin
XXI (4-6): 269-286. April~June 1932.

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practices are based upon the. theory that vultures, attracted by the baits,

will frighten away the horned larks. These methods, however; are ineffective,
as horned larks, coming from their roosting places in stubble or grassfields,

generally appear in the fields soon after sunrise, whereas the vultures @o not
take wing until the air has warmed up, often two or three hours later. Hence

the horned larks have considerable opportunity for feeding before the vultures
appear. Furthermore, horned larks have been observed time after time feeding
within 15 feet of vultures and evincing no fear. _

The use of the dead white chickens, however, has a secondary effect of
some slight value. As the carcasses are eaten by predators a mass of white
feathers is liberated. In much of the area where damage by horned larks
occurs, there is a strong breeze nearly every day, and the white feathers
flutter across the fields before the wind. As long as feathers are moving
in sufficient density, they have some effect in repelling larks.

Scarecrows.--A great variety of scarecrows has been devised. General
faults of these are: First, that they are usually sparsely distributed, and
second, that they have nc motion. To remedy these faults costs more than
other methods here recommended. As a rule, scarecrows are rank failures.

One rancher built and placed in his field a number of home-made wind-
mills with blades ebout 2 feet long. In the strong midéay sea breeze common
in that district the winémills whirl vigorously and me considerable noise.
Horned larks remained at some distance from these machines, but the cost of
placing them over a field in numbers sufficient to protect the crop would be
prohibitive.

Paper Confetti.--OQne ingenious rancher, in a district which has a con=
stant sea breeze, hit upon the idea of tearing old newsprint into small pieces
and throwing them into the air at the windward margin of the field whence
they were rolled and tumbled across the field by. the breeze. As long as the
density of torn paper was sufficient end the motion continued, horned larks
avoided the field. Naturally the rancher tired of the constant attention
demanded and did not continue the trial. Shortly afterward, homed larks came
back into the field and destroyed elmost the entire planting.

he methods here discussed that
ect is that of placing pieces

Papers on the Ground.--The first of
appear to have any continuing protective ef
of paper on the ground, weighted down with clods of earth. The degree of
success depends upon the frequency of Gistribution of the papers over the
field, and the use of strips of paper weighted at one end rather than large
sheets of paper that have little motion. In most of the ceases observed, this
method did not give complete protection, although in a few it was clearly
succéssful. In localities where the crops attacked are germinated in water-
saturated soil or are irrigated several times during the period of attack,
this method has little merit.

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Stakes and Flags.--Next in merit in the progressive study of horned
lark repulsion is the "stake and flac" method. Here stakes, often laths, are
fixed in the soil and strips of cloth or paper attached to their tops. The
"flag" usually is tied to the top of the stake with e “hort string, but some-

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times it is tacked in that position. Flagging affords crop protection in
direct ratio to the density of stakes and flags, and to the care given in
replacing flags torn away by wind or rain. For complete protection the
stakes cannot safely be placed more than 25 feet apart in each direction,
and in the case of persistent attack should be not more than 20 feet apart.

Continuous String Flaggine.--The best of the protective methods ob-
served,namely, "continuous string flagging," has come into wide use during
the past few seasons. The materials necessary are:

Heavy stakes, such as laths or car strips, at least 4 feet long.
Strong cotton wrapping twine, 4- or 6-ply.
Paper or cloth streamers, 2 to 2 1/2 inches wide, 20 to 24 inches long.

The stakes are driven firmly into the ground, and may be 50 or more
feet apart in the row. Those at each end must be braced. (See accompanying
illustration. )

The cotton wrapping twine is stretched from stake to stake, half-
hitched about the top of each, continuously across the field. The cord used
need not be large, but must be strong enough to withstand the strain of ten
or more streamers to each 50-foot section, in the prevailing winds of the
Gistrict where used. Four-ply cotton wrapping twine is standard.

Paper or cloth streamers 2 to 2 1/2 inches wide by 20 to 24 inches long
ere prepared. These streamers should be fastened to the cord at 5-foot in-
tervals, making 10 streamers to each 50-foot section between the stakes.

There is no definite rule in regard to the material of which streamers are

made. In general, white cloth or paper is used; cloth is of course more durable.
When cloth is used, a good quality of heavily sized muslin is preferable;

lighter grades will wear out by whipping in the wind and may curl up and roll
into strings that have little effect.

Old newspapers may be used, but any soft paper lacks durability and it
takes time to replace those that tear away. Heavy butcher's paper is fairly
cheap, quite durable, and sufficiently light in color to work effectively.
Some growers use black or varicolored streamers with success; but it appears
that color has little to do with the effectiveness of the method, and that the
motion of the streamers is the major feature of value. Unless for a local
reason, however, there is distinct economy in the use of colored streamers,
it is well to use white because of better visibility. Additional effect may
be obtained if the rancher plants his crop in rows at a wide angle to the
prevailing wind direction, and thus obtains greater motion of the streamers.

One rancher employed the waxed paper used for lining lettuce crates,
which was cut into streamers 2 1/2 by 21 inches, the tail of each streamer be-
ing slit for fully 15 inches. This was in a locality where the daily sea breeze
was strong, and the split streamers attained a maximum of motion, accompanied
by a crackling and snapping noise that could be heard for a long distance.
Horned larks showed a marked aversion to the noise of these streamers and vould
not even fly over the fields except at a considerable height. A two-ply, heavy
crepe paper, the two plies stuck together with asphaltum, also is used. It is

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PLAN FOR STAKING AND FLAGGING ONE ACRE.
208..X 208

FP}
ia 4 PLY COTTON CORD

| '— PAPER OR CLOTH
pie | STREAMER
t

Wy y
SSE ORS)

NI a — NZ, a WY Sz we Wi a NZ; ete Ny wy Wh VN \V Ye Wi VW
{ / ~. 2 ™ RS Ty ASA AD 4 FS A~A ~~ 4 Si = RXN2 =: S; : ’ N
SSX rr SS SSS SSS SSE SSNS SS SNES
NYWQAYN =~ SOS SSS NOS SS SSS
Sc, && Ss w—wWS i. nsked BEOWSSSSSSSS
YSERA. SSS
RYSSSgann“n“~“vsSssePSS

PLAN OF END STAKE AND FIRST TWO STREAMERS
CONTINUOUS STRING FLAGGING

==

durable and will stand wp in heavy wind end through severe rains. Split-
tailed streamers of this paper are said to be very noisy and effective. It

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is reported to be cheaper than muslin and more durable than the cloth streamers

When paper streamers are to be used it is suggested that prices includ-
ing euttings be obtained from a local company. Machine cutting of the streamers
at the paper mill will add little to tne cost, while cutting streamers by nand
on tne ranch is a long and laborious tack.

Peper streamers may either be pinned to the cord or tied to it with a
short string; the latter is considered best as it permits maximum motion. ‘The
end of the streamer must be folded back so as to give additional strength where
tied. When the period of demage has passed, the streamers should be removed
from the cord and the cord rolled up and vreserved for use the following season

Cloth streamers also may be tied to the coré with a short string, or
whey may be knotted directly to the cord as it is being stretched from stake
to stake. When cloth streamers are used, the cord with streamers attached
may de wound. upen notchec boards and kept intact wtil egain needed.

Meny of the crops attacked by horned larks are from in bed-rows;
others are grown in single rows on a flat-surfaced field. The distance between
rows or beds will determine the exact distance between the rows of stakes and
streamers. For example, in a bed-rowed crop where the centers of the beds
are exactly 2? inches apart, 2 row of stakes ean be placed in the centcr of
each tenth bed, or about 23 feet apart, or in the center of each twelfth bed,
or 28 feet apart. The rows of stakes and streamers should never be placed
more than 30 feet apart, and it is doubtful whether any situation would arise
that would demand the placing of the rows closer than 20 feet apart. In
common field usage the rows of stakes average about 25 feet apart.

This method of prote¢ting plantlets against attack by horned larks is
strongly recommenced to agricultural officiels and ranchers faced with this
problem. When properly done it is an efficient method of preventing loss.
No time should be wasted on trials of uneertain and-:Jess efficient methods.
It is 7S 28 install conti pao string flaseine in advance of, or at the
first sign axteck un on, the crop.

This method I§ NOT FECOMMETOAD for protection against birds of any
Species other taan horned larks.

gstimate of Costs of Sontinuois String Flepeing

the cost of epplying the contimuovs string flegeing methot is moderate

“when one cons sldcrs the immense losses somotines occasioned by failure to

A sap the crop... Costs will va ary with wages in each lo@ality. For materiels
ee 4% will be from approximately €5¢ per acre, with paper streamers, to

ap Toximately $l, 85 acre, with cloth. This estimate is. based upon the
matériais necegsary we stake and fing one acre, 208 by 203 feet, with the
stakes placed 50 feet apart in the row and the rows spaced 25 feet apart, the
prices being obtained in January “1936 in the trading center of an area in
which hundreds of acres of crops are protected each year by this method. It
should be noted that this carries the stakes and flags to the border of the

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acre. ‘The stakes on the wouncary, therefore, will serve the adjacent acre,
which will thus ee one less row; however, an adjacent acre at the ends
of rows i require the same quantity of twine and flags as the original,
thoush the adjecent acre at the sides will require one row less.

heath, 4=f OO treet si on ee +e 2 2° S.- See Boe per bunds
Car strips, 4! by 1/2" b by 1 3/4n, . . 70¢ per hundreé, $5.30 per
thousand.

iyine:

Four-ply cotton vrapping twine may be procured at varying prices,
rancing from 76¢ to $1.25 for a 2-pound cone. One dealer offeréd
a2 1/2-pound cone for 80¢. The best grade of 4-ply cotton wrap=
ping twine runs about 2,000 linear feet per pound.

Streamers:
White muslin, heavily sized, good grade, ranged from 9¢ to 15% ver
yard at various stores. Bolts averaged 540 square feet (36 inches
by 180) feet).

Heavy, light-tan butcher's paper. A 24-inch roll, approximately
4,000 linear feet, weighing 40 to 42 pounds, was priced at
$4.25 per hundred-weight. Prepared streamers of this material, cut
piy/2 by 24 inches by a paper company, were offered at 40¢ per
thousand.

Streamers cut from waxed lettuce-paper were offered by a paper
company at 70O¢ per hundred. Lettuce ae undoubtedly could
obtain the sheet paper from their packing houses at considerable
reduction.

For the basic acre to be flagged, the following materiais should

costs

Vith muslin:
Stakes (car strips)--45 ... ‘ uk Ae eRe
4-piy cotton wrapping peeeee! OC oO ft. Bis owe eh SU Gan OREaS
Muslin streamers, 2 by 24 inches--360-°...°. .-. - « » 1.15
$1.85

With pepcr:
Stekes (car strips)—=45 ... care
4-ply cotten wrapping twins-~2, 000 ft. 3] cisretnh . &. Saae
360 already~cut butcher-paper streamers . 1. .« s» -» =» + Q.15
$0.85

3/ Ba a on offer of 2-pound cone for 76¢. 1,800 linear feet is
necessary for the continuous string, and 200 feet are allowed for tying.

tT Oss