Birds known to eat the boll weevil


Material Information

Birds known to eat the boll weevil
Physical Description:
Bailey, Vernon, 1864-1942
U.S. Dept. of Agriculture, Biological Survey ( Washington, D.C )
Publication Date:

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Resource Identifier:
oclc - 18231240
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Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Front Matter
        Front Matter 1
        Front Matter 2
    Title Page
        Page 1
        Page 2
    Letter of transmittal
        Page 3
        Page 4
    Table of Contents
        Page 5
        Page 6
    Main body
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
    Back Cover
        Back Cover 1
        Back Cover 2
Full Text

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"Washington, D. C., July 25, 1905.
Sim: I have the honor to transmit herewith for publication as Bul-
etin No. 22 of the Biological Survey a preliminary report upon birds
Their relation to the boll weevil, by Vernon Bailey. In view of
he fact that this destructive insect continues to extend its range into
occupied cotton regions, it is obvious that no factor in the warfare
against it can safely be neglected. The relation of birds to the boll
reevil and the extent of dependence that can be placed upon the
former in limiting its inroads are not well understood. As requests
rom the cotton districts for information upon the subject have been
many and urgent, field investigations, of which the present bulletin
* the first outcome, are now being conducted by the Biological Sur-
rey, with a view to ascertaining the particular birds which perform
hie most important service in preying upon the weevil, to the end
hat special protection be extended to such species.
Acting Chief, Biological Survey.
Secretary of Agriculture.


lntodu o -------------------------------------------------------------- 7
J'iddnotes----------------------------------------------------- 8
Condition of cotton fields during investigations-------------------------- 12
.Conditions of bird life during investigations----------------------------- 13
Decrease in number of weevils ----------------------------------------- 13
Examination of bird stomachs.. ------------... -------------------------- 14
Investigations by Bureau of Entomology ----------------------------- 14
Conclusions and recommendations --------------------------------14
List of birds which had eaten boll weevils ------------------------------ 16




YFor several years past the cotton growers of Texas, as is well
Mown, have sustained enormous losses through the ravages of cotton
:I:l weevils. Remedial measures of various kinds have been tried,
9it, though some of these undoubtedly have proved more or less
tective, the number of insects does not seem to have been materially
hduced, and their progress into other cotton-producing districts has
en steady, the borders of their range widening yearly.
IThe extent to which the native birds feed upon this, one of the
iost destructive insect pests that have ever appeared in the United
states, is yet but imperfectly understood, and investigations are now
ng conducted by the Biological Survey with a view to determin-
g just what species feed upon the weevil and the extent to which
k enters into the fare of each.
SThe fact that for the past twelve years the weevil has been steadily
reading over the cotton-producing area forbids the assumption
6at birds are likely ever to exterminate the insects. Nevertheless,
a will appear from facts presented below, certain species prey upon
ke weevil to a greater or less extent, and it is probable that by care-
idly protecting such species and by encouraging their increase the
cod work they now do may be greatly augmented in the future.
Ius, the question of extermination aside, birds are likely to prove
n effective ally in checking the increase of the pest. The fact that
other species of weevils are a favorite diet with many of our insec-
ivorous birds has been proved by previous investigations.I More-
iver, it is well known that when a new insect first appears in a
district birds are somewhat slow in acquiring a taste for it and in
efficiently learning its haunts and hiding places to effectively pursue
pd capture it. It is probable, therefore, that some birds which at
:.resent are not known to attack the weevil at all will later acquire
i| taste for it, and that others which now feed upon it sparingly will
i' future feed upon it to % greater extent.
SThe present report is in response to urgent appeals from the
aS Food of Bobolink, Blackbirds, and Grackles. by F. E. L. Beal, Biological
trrey Bulletin No. 13, pp. 22, 44, 52, 69, and 189.


infested and threatened cotton districts for reliable information as to
the species of birds which feed upon the boll weevil. Field work for
the purpose of obtaining this information was begun at Seguin,
Guadalupe County, in southern Texas, October 31, 1904, and was
carried on at several localities in the boll weevil district until Decem-
ber 16. Investigations now in progress in the field and laboratory
will cover the remainder of the year, including the season of greatest
abundance and activity of the weevils, and will furnish material for
more general and definite conclusions.
In the course of their investigations of the boll weevil the Entomolo-
gists of the Department examined the stomachs of a large number of
birds collected in and around the cotton fields, and the results appear
mrn Bulletin 51 of the Bureau of Entomology, on the Mexican Cotton
Boll Weevil. These results have been tabulated and appear in the
summary of the present report.
The following field notes relate only to the birds found to have
eaten boll weevils.
Carolina wren (Thryothorus ludovicianus).-Carolina wrens were
common at Columbus, Eagle Lake, and Wharton, were fairly abun-
dant at Navasota, and a few were seen at Seguin. They were rarely
found in the fields, but were constantly dodging in and out of the
brush heaps, log piles, and vine tangles, running over the rough
bark of old trunks and roots and logs, peeking and peering and pick-
ing in all of the dark corners overlooked by larger species, and even
hunting among the dry leaves on the ground under logs and brush.
They were generally in pairs, and sometimes two pairs were found in
one brush heap, while almost every thicket or vine tangle contained
one or several of the birds. Those observed were apparently perma-
nent residents. Seven were shot, 5 of which had eaten boll weevils
for breakfast, and one of these had eaten 2, making 6 weevils to 7
birds at one meal. As all but one of the birds were taken after the
frosts, there is no reason to doubt that the good work of this species
goes on throughout the winter.
Titlark, Pipit (Anthus pend.ilraniiwts).-Titlarks were first seen at
Columbus, November 14, and this evidently was about their first
appearance. Large flocks were seen in the cotton fields the next day,
and at Eagle Lake and Wharton a few days later. At Navasota
they were still numerous in flocks of 100 or more at the time of my
departure, December 16. At Wharton and Eagle Lake, where most
of the birds were collected, flocks of 100 to 500 were constantly in
the cotton fields, seeking food as they ran or walked over the ground.
WhIien flushed they flew to another part of the field or to a neighbor-
ing field, disappearing among the cotton stalks. The eight indi-

D.I UJL. MUICA UW JL AUAULMAD ll L UAJIr WVlWI tify. tjuzznzuca %A11
;ahbutmndance of these birds, none of the other species collected
l lthaem as weevil destroyers, at least at this particular season.
Ris perhaps of interest to add that the titlarks breed in great
above timber line in the high mountains of New Mexico,
and northward, and winter in still greater numbers in
iei... rn Texas.
|Zia:.i: -reated titmouse, Tomtit (BEoolophus atricristatus).-Tomtits
fairly common at Seguin and Navasota, in their usual resident
bers. They hunt mainly over the branches and trunks of the
where they pry into all the cracks and crevices of bark and
Oen wood. Only 2 were shot, 1 of which had eaten a boll weevil.
SWestern meadow lark (Sturnella magna neglecta).-The western
rIeadow larks were seen from the train between Austin and San
rktonio, October 28, rising in flocks of 10 to 100 from almost every
Iwtton field along the railroad. In one field of not more than 20
Acres 108 birds were counted. At Seguin they were abundant from
IOetober 31 to November 12, and at Eagle Lake they were common
,to November 19 over the open country, or, sometimes, in company
wi,,th the more common Florida form, argutula, in "the fields. At
Navasota they were still abundant on the open prairie and in fields
up to December 16, but less common in the fields and wooded country
than argutula. These dates merely indicate that the meadow larks
shad arrived in full force from the north before my arrival in the
ield and remained in undiminished numbers to the time of my
A&parture after the middle of December. The greater number of
'those sent in for examination were shot from November 1 to 12 at
:SBeguin, where only neglecta was found. Here it was one of the most
abundant birds in the fields. In walking across a 40-acre cotton
ield I usually flushed 200 or 300 western meadow larks. In corn and
sorghum fields the birds were just as common, but as fully three-
f:ourths of the fields in this region are devoted to cotton the greater
numbers of birds were found in the cotton fields. The open nature
,of these fields, with the partial concealment and protection offered
iby the rows of cotton stalks, makes them favorite feeding ground
ior the larks.
E The 18 boll weevils eaten by the 64 birds probably represent a fair
.IAverage of the number of weevils eaten at one meal at this season.
allowing the birds at least two meals a day, the birds safely may be
assumed to destroy over 50 percent of their own number in weevils
-daily. This good work carried on throughout the fall and winter
r months can not fail to have an important effect on the next year's
,Ov of weevils.


Florida meadow lark (Sturnella magna argutula).-The Florida
meadow larks were first found at Eagle Lake, November 18, where
they were more numerous than neglecta, with which they were asso-
ciated in the cotton fields. At Wharton they were common and the
only form found. By the nature of the country they were restricted
to the large cotton and cane fields which occupy the only clearings in
the heavy forest; and until the sugar cane is cut, usually late in
November, the larks were practically restricted to the cotton fields.
At Navasota they were common up to my departure, December 16,
and their favorite resorts were the cotton and corn fields of the tim-
bered river bottoms. Here the western meadow lark was associated
with them to some extent, but seemed to prefer the open prairie
strips of this half-forested region. In abundance and habits the
Florida form does not differ greatly from the western meadow lark,
and the conclusions in regard to one would apply in a general way to
both. The slightly smaller proportion of boll weevils eaten by
argutula is probably due to the fact that the specimens were collected
later in the season.
Common phwebe (Sayornis phobe).-The common phoebe was the
only member of the flycatcher group seen, and it was common at
every locality visited from November 1 to December 16. It is a winter
resident only in this part of Texas, arriving usually in October
and remaining till April. As it did not diminish in numbers up to
the middle of December, it evidently remains in full force throughout
the winter. It frequents brushy and open country and is often found
during feeding hours sitting on top of a cotton plant or cornstalk
out in a field. In walking across a cotton field half a dozen birds
were sometimes seen. Most of their food was taken on the wing, but
they often dived to the ground in pursuit of insects. The fact that
2 out of 10 birds had eaten boll weevils suggests that the several
other species of flycatchers which spend the summer in the boll-
weevil region may do important service in snapping up weevils on
the wing during the period of greatest activity of the insect.
Redwing blackbird (Agelaius phiirtieuis).-A few redwing black-
birds were found at Seguin November 7; two days later several small
flocks were seen; and b)y the 12th they were fairly common in flocks
of 20 to 50. At Columbus a few were shot from a flock of 100 or more
in a cotton field November 15, and other large flocks were seen. At
Eagle Lake. on the edge of the prairie, November 16 to 19, the red-
wings in flocks were innumerable, and I could only estimate them
ut hundreds of thousands of individuals. Numbers of cowbirds were
in these flocks, but most of them were redwings. At a distance the
flocks looked like clouds of smoke, but nearer, as they rose and
wheeled and circled over the fields, they suggested rapidly moving
clouds or (ldust in the desert. As they settled down, they blackened


f io of 1,000 or so to different parts of the fields. As these
s5avettled among the cotton stalks, it was probably mainly for
:.nd weed seeds, which with broken rice comprised the contents
of the crops and gizzards, but the fact that 2 out of the 27
duals shot had eaten boll weevils is of some significance in
Adoration of the vast numbers of the birds.
eitem savanna sparrow (Passerculus sandwichensis alaudinus).--
em savanna sparrows were abundant at all of the localities
Hted during the time of my stay in Texas. They are so small and
*Cospicuous as to escape general notice, but as I walked through
cxeotton fields they were constantly darting out from before me,
luging to right and left to avoid flight, or flying a short distance
Dropping again into the grass. Out of 18 shot only 1 was found
.Ihave eaten a boll weevil, so the importance of the species is not
F.Bt, even considering the abundance of the individuals.
W.hiite-throated sparrow (Zonotrichia albicollis) .-White-throated
I ows were first seen at Eagle Lake November 16, where they
the place of the white-crowned sparrow found at Seguin. They
iere common at Wharton and extremely numerous at Navasota up
0 the close of my work. Their favorite feeding grounds were in the
tickets and brushy borders of fields, where they were constantly
i"stling among the weeds and leaves in search of food. Of the 9
iecimens collected only 1 had eaten a boll weevil.
Brown thrasher (Toxostoma rufum).-One brown thrasher was
m&n at Columbus November 15 and one at Wharton November 17.
A. few were seen at Liberty November 21, and they were common
throughout the Big Thicket country near Saratoga and at Navasota
up to December 16. At Navasota, where all of the specimens were
procured, December 10 to 15, they were fairly abundant in the -
thickets and brush rows around the edges of fields. Individuals
were easily located at some distance by the noise they made scratch-
ing and running among the dry leaves, and a good many were shot
In the hope that they were unearthing and eating boll weevils. Of
he 28 specimens, however, but 1 had eaten a boll weevil.
Texas bobwhite (Colinus virginianus texanus).-Thirty-five speci-
nens of Texas bobwhite were collected at Seguin between November
| and 12, where at the opening of the hunting season they were
abundant, Later a few flocks were seen at or near Columbus, Eagle
Lake, Wharton, and Navasota, but at all of these places they were
comparatively scarce and the flocks were scattered and wild. At
Seguin almost every field and pasture contained one to three coveys
Of 10 to 20 quail, which were generally to be found not far from their


chosen roosting thickets or feeding grounds. On many of the farms
one or more flocks had taken up quarters close to the houses or in the
orchard or garden and had become comparatively tame. At Mr.
Neel's place, where most of my work was done, a flock of about a
dozen birds lived in the orchard, garden, and barnyard, and when
frightened rarely flew beyond these limits. The farthest from the
house that I ever found them was in the edge of the adjoining cotton
field, where toward sundown they were often seen feeding. Mr.
Neel called my attention to the fact that about one-third more cotton:
had been gathered from the part of the field near the house, where
his 100 chickens and these quail habitually fed during the summer,
than over the rest of the field. At the farther end of this field
another flock of 8 or 10 quail lived in the mesquite brush and made
daily rounds out into the field to feed. The birds were shot in other
fields farther from the house, and in all cases either out in the fields,
where they were usually found feeding during the morning and
evening hours, or in the brush along the edges of the fields, where
they roosted at night and were generally found during the middle of
the day.
The fact that at this time the quail were feeding almost exclusively
on weed seeds was evidently due to the great abundance of freshly
ripened seeds. During the summer months the quail, especially
the young, are known to feed to a much greater extent on insect food,
and it is reasonable to expect that later in the season, especially dur-
ing the winter and spring months, after the weevils have left the
cotton, the quail scratch them up from under leaves and rubbish.

At the beginning of the field work at Seguin, October 31, 1904,
cotton picking was just completed; but owing to recent rains a sec-
ond crop of leaves, buds, and young bolls had started on the tops of
the cotton plants, and the weevils were actively engaged in feeding
on the buds or young bolls within the cover of the closed squares.
The weevils apparently were less abundant than during the summer
months, an(d as their breeding season seemed to have closed they were
l)robabl)ly also less active. Otherwise, the conditions so far as related
to the weevils were essentially the same as in summer. These condi-
tions were unchanged up to November 12, when the first hard frost
of the season occurred over most of southern Texas, including Se-
gulin, where investigations were in progress at the time. Most of the
cotton was killed, and )y the third day the weevils had left the dead
and dried-ul) cotton tops and disappeared. Still, a few fields or parts
of fields escaped the frost, and from November 13 to 20, in the vicin-
ity' of ('ollulnbus, Eagle Lake, and Wharton, a large number of birds
wer(e shot in and around these fields to determine whether they were

.... .later, at Navasota, December 10 to 16, long after all the cot-
B td. been killed and dried up and the weevils forced to seek
.quarters, 100 birds were collected, mainly in woods, brush,
Siyeed patches surrounding the cotton fields. As no boll weevils
M*be found in the cotton fields at this time it is fair to assume
Mey had gone into winter quarters. Such, briefly, was the status
cotton fields in relation to the weevils during the investigations.
t the several localities the species of birds inhabiting the cotton
varied from time to time. At Seguin western species predomi-
H while at Wharton and Navasota mainly eastern birds were
ii During the time covered by the investigations the resident
birds were leaving and the winter species were arriving.
i y of the insectivorous summer residents, such as orioles, flycatch-
swallows, martins, night-hawks, and whip-poor-wills, had disap-
d when the work began, and their places were filled by numerous
-~~-ting migrants of the sparrow family. Moreover, the well-
....wn change of food habits of resident species, like the quail, which
...largely insectivorous during the summer and mainly seed-eating
Ming the fall and winter, when the present investigations were
efly made, must be taken into account in estimating their value as
s years of weevils.
I1 'Of the 354 birds killed, approximately 10 per cent had eaten boll
weevils. Examination of the stomachs collected at different dates
thows a slight decrease in the number of weevils eaten as the season
Ivanced. In round numbers, those eaten during the period of green
htWton, October 31 to November 12, were 11 per cent of the number of
drds killed; for the period of change from green to dry after the
first hard frost, November 13 to 20, 10 per cent of the number of
; for the period of dry cotton after the disappearance of the
vils, December 10 to 16, 8 per cent. The fact, as stated above,
t fewer weevils appear in the stomachs of birds shot during the
Period than in the earlier one, is evidently due to the diminished
*apply of weevils.
Out of the 38 species of birds collected which had not eaten boll
ls, 17 species were represented by only 1 specimen each, hence
Negative evidence in regard to these is of little significance. If
ter numbers of the same species had been collected or if they had


been collected at another season they might appear among the number
of enemies of the weevil.
It being found impracticable in the field to determine with any
degree of certainty whether or not the birds had eaten boll weevils,
all stomachs were preserved and sent to Washington, where they were
examined and the boll weevils identified by Prof. F. E. L. Beal,
of the Biological Survey.

In Bulletin No. 51, published by the Bureau of Entomology, on the
Mexican Cotton Boll Weevil, are given the results of the examina-
tion by Mr. E. A. Schwarz of the stomachs of 17 species of birds.
These birds are added to the list presented below, and indicated by
stars, and the data are utilized in the general conclusions. Except
those of the mourning doves and quail, the stomachs were taken from
birds collected at Victoria, Tex., and of these 100 were obtained
during the last week of February, 7 during June, 3 during July, 26
during August, and 380 between September and December."a
Out of the 17 species of birds, 11 species had eaten boll weevils,
as appears in the following table. These 11 species comprised 237
individuals, of which 44 individuals had eaten boll weevils. The 6
species of birds that had not eaten weevils were mourning dove,
quail, redwing blackbird, lark sparrow, grassfinch, and blue-gray
Eliminating the mourning doves, which practically never eat
insects, and the quail, which eat very few at the season when these
were collected (November), there remains a total of 255 bird stom-
achs examined, of which 44 contained boll weevils.

The total number of stomachs examined in the Biological Survey
and Bureau of Entomology, aside from mourning doves and quail,
was 570. Of these, 78, or 13.6 per cent, contained boll weevils. The
total number of weevils eaten by 78 birds was 101, or 17.7 per cent of
the total number of stomachs.
With reference to the comparatively small number of cotton boll
weevils eaten by any of the birds examined it should be borne in
mind that during the time when most of the birds were collected
adult weevils were not numerous. During the earlier period of the
field work (October 31 to November 12) the insects were practically
a The Mexican Cotton Boll Weevil, by W. D. Hunter and W. E. Hinds, Bulle-
tin No. 51, Bureau of Entomology, Department of Agriculture, 1905, p. 151.

could be estimated, and in no case did they average more
..... to a hill of cotton, and rarely more than one to three hills.
W athe number of weevils consumed in a field equals 17.7 per
o the number of birds occupying that field per day, or, by allow-
h birds two meals a day, 35.5 per cent of their number, the
".... on of weevils is after all comparatively rapid; but as this
..... .... "..:..
W depends largely on the abundance of the weevils-the more
I .... the weevils naturally the greater the number eaten-their
plete extermination by birds is hardly to be expected. It is
bible to learn just how many times a day a bird's stomach is
and emptied, but it is well known that birds with crops fill
IMI crop and stomach twice a day. Most insectivorous birds are
fhout crops, however, and as they usually feed more or less con-
4ouously from early morning to evening it is not improbable that
& stomach is filled and emptied five or six times daily. As exam-
ftions of bird stomachs are based upon only a small portion of the
[*y's food, the number of weevils detected is probably far less than
jare actually destroyed daily. Even the incomplete data thus far
p obtained, however, suggest that without the aid of the birds no cotton
an be raised in the weevil-infested area.
SUntil two years ago the protection afforded birds by law in the
State of Texas was very inadequate, and many of the most important
[insectivorous species were slaughtered for sport or for their plumage.
"Thus their numbers were greatly reduced and some kinds were
nearly exterminated. In 1903 a State law was passed providing for
the protection of all nongame birds and fixing a close season for
Turkeys, grouse, quail, and doves, but giving no protection to kill-
deer, plover, snipe, and many other insectivorous shore birds which
are now legitimate game at all seasons. The law in respect to the
shore birds should be changed, since it is known that at least one
species of plover, the killdeer, feeds upon cotton boll weevils to a
greater or less extent, one of the two specimens examined having eaten
three adult insects. The fact that the killdeer remains in and about
the cotton fields the year through emphasizes the importance not only
:of extending protection to this particular bird at all seasons, but of
protecting as well the other plovers and shore birds which have simi-
;1h ectivorous habits. The desirability of such protection is em-
JZed by the fact that formerly the upland plover, one of the most
sectivorous of all species, abounded on the Texas prairies. It was,
ever, slaughtered by the wagon load for market, and now where it
.e. swarmed it is comparatively rare. It is highly probable that
is species would lend efficient aid in the warfare against the weevil

were it permitted to winter unmolested within the borders of the
State. Moreover, the present law protecting the nongame birds, such
as meadow larks, grackles, orioles, and flycatchers, is to no small
extent disregarded, and many of the most beneficial birds are being
destroyed. An efficient warden service would no doubt aid in pre-
serving the birds, but the bird laws of a State can be made really
effective only when supported by public sentiment, prompted by a
widespread knowledge and appreciation of the services birds render
to man. When the value of these services in the present war against
the boll weevil is understood throughout the cotton States it must
result in an enlightened public sentiment in favor of the birds.
The necessity of extending every possible protection and encour-
agement to insectivorous birds within the cotton-producing districts
of Texas and other Southern States is strongly urged.



ber of

Carolina wren ..---....-!
Titlark, Pipit------------
Tomtit, Black-crested I
titmouse ........------..----.
Western meadow lark.. -
Florida meadow lark ...- I
Common phoebe------
Redwing blackbird ... -
White-throated spar-
row ................
Western savanna spar-
row........... --- ..--.
Brown thrasher.......
Texas bobwhite .........

ber Num-
that ber
had of boll
eaten wee-i
boll vils
wee- eaten.

5 6
4! 5


* Brewer blackbird -----
* Cowbird.-- --
* Jackdaw, Great-tailed
grackle ...............-----------i
* Western meadow lark!
* Mockingbird ........-.
* Butcherbird -..-----...-.
* Killdeer...............
* Baltimore oriole ......
* Dickcissel .............
* Scissor-tail flycatcher.
* Common phoebe ......


Num- ber
her of that
birds eaten
ined.a- boll

10 5
31 4

10 2
153 23
17 3
7 2
2 1
3 1
1 1
1 1
2 1

475 79

.See Bulletin 51, Bureau of Entomology, 1005.

of boll


F iM

* Examined by Mr. E. A. Schwarz.


*. :


* *-:i

". "

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