United States Department of Agriculture
Bureau of Biological S'.rvey

Wi Idl ife Research and Management Leaflet

■Washington, D. C.

BOTULISM, A RECURRING- EAZABD TO WATERFOWL

With Notes on Recent Outbreaks in the United States
Canada., and Australi a

By E. R. Kalrabach, Senior Biologist, Section of Food Habits
Division of Wildlife Research

A little-known, yet dismal

picture

Outbreaks since 1932 . . .

In the United States . .

In Canada

Content s

Pago

1

3
3
5

Outbreaks since 1932 — Cont'd
In Australia ........

Safeguards for the future . .
Literature cited

Page

6
7

8

A LITTLE-KNOWN, YET DISMAL PICTURE

Despite the great number of ducks and shore birds that have per-
ished from botulism l/ in the past quarter of a century, relatively few
sportsmen, naturalists, or bacteriologists have ever seen a wild bird
afflicted with the disease. Even fewer have witnessed a devastating out-
break. Reasons for this are not hard to find. Besides the fact that
outbreaks of botulism among wild birds are localized, sporadic, and often
of short duration, they are corollaries of stagnant, Steaming , ; malodorous
flats and fathomless mud. They also reach their peak usually beneath the
untempered sun of July, August, and September. Under such conditions the
"call of the wild" loses some of its appeal even among the more ardent
defenders of our thinning lines of waterfowl. By the time the hunting
season opens, however, the environmental conditions conducive to the mal-
ady may have so changed that it vanishes almost' as quickly as it appeared
This led some into the erroneous belief that the shooting that comes with
the opening of the season is all that is needed to remedy the situation.

l/ Referred to in earlier literature as alkali poisoning, duck
sickness, and western duck sickness.

Intelligent shooting with a rifle in infected areas is one of the few remedial
measures at man's command, hut promiscuous shooting by hunters whose main ob-
jective .is to kill "birds is quite a different thing.

i / VJ - • ' ; s 1

To those true sportsmen who have viewed the real tragedy of botulism
among wild fowl or have experienced the regret that comes from close contact
with an outbreak 'of devastating proportions, the reaction is quite different.
In compliment let it be said that there are those whom the sickening sight of
botulism has induced to lay aside the gun. At times of such crises, often
sudden and unavoidable, the toll of even one added gun is worth saving.

In the summer of 1910 a mysterious malady, demonstrated in later years
to be botulism (l)f±/, took a disastrous toll from waterfowl dwelling in marsh
areas adjacent to Great Salt Lake , Utah. That calamity first attracted na-
tional attention to a disease that is today considered one of the most de-
structive natural checks on migratory waterfowl and shore birds dwelling in or
migrating through the States west of the 100th meridian. Still fresh in the
minds of men who hunted for the market in those days are the impressions of
that epizootic. There are stories of how one could walk for miles along the
shore of Willard Spur and Bear River Bay at the northern end of Great Salt Lake
stepping from one dead body to another, and when wind and waves had drifted
them ashore, dense windrows of carcasses marked the edge. As the season ad-
vanced the accumulating bodies created a veritable wildlife shambles, and the
resultant decay made it almost impossible to inspect some areas. No one wit-
nessing the devastation that year felt the need or desire of counting the dead.
"Millions" seemed so fitting an estimate that the extent of mortality usually
was considered cn that basis.

It was not until later years, when attempts were made to improve sani-
tary conditions by gathering and disposing of the bodies, that actual counts
were made of the dead. In each of two successive years (1912 and IS 13) more
than 40,000 birds were ricked up in a month at the mouth of Bear River, Utah
(5). In 1914, 8,000 to 10.000 dead ducks were found on a 2-mile stretch along
one of the lower channels of the Weber River, and in 1S32 a conservative esti-
mate placed the season's mortality at the northern end of Great Salt Lake at
more than a quarter of a million birds. Interpreted, this is equivalent to
the present 1-day bag for each member of an army of more than 25,000 huntersl

Although the marshlands bordering Great Salt Lake have been the scene
of more extensive outbreaks of botulism among wild fowl than any other area
of equal size, the disease has been reported from the Prairie Provinces of
Canada to New Mexico, Arizona, and the Imperial Valley in California; and from
southwestern Minnesota., western Nebraska, and the Panhandle of Texas to the
west coast. TTnat appears to have been the same malady has also been reported
from Mexico, Uruguay, and Australia (JL, pp. 31, 32; and 2).

2/ Numbers in parentheses refer to the Literature Cited on page 8.

OUTBREAKS SINCE 1932

The foregoing are just a few of the high lights in the story of
"botulism manifested "before its cause Was discovered and "before information
regarding its history and range was compiled (l). The most important out-
breaks occurring within the past 5 years (1933-37) are discussed in the fol-
lowing paragraphs. It must be explained, however, that definite bacteriolog-
ical proof of the presence of this disease is rarely available. When such a
diagnosis is lacking, records have been included on the ba.sis of symptoms
noted, the course of the epizootic, and the nature of environmental condi-
tions.

It is emphasized, furthermore, that the reported outbreaks doubtless
constitute only a fraction of those that actually occur. The more disas-
trous ones and those that appear in frequented areas are likely to be re-
corded, but many minor on; a may be in inaccessible areas, and these, in the
aggregate^ may account, fpr^a^ignif i cant total of dead birds. Hence this
presentation does not purport to be a comprehensive summary of the outbreaks
of avian botulism that have occurred during the period indicated.

In the United States

In the United States, botulism among wild birds during the past 5
years has appeared in what might be termed normal frequency . and intensity
as judged by the history of the malady daring the past quarter of a cen-
tury. Although there have been no outbreaks of mammoth proportions com-
parable with that of 1910, mortality has been severe, and the disease has
appeared in an increasing number of localities. The latter circumstance
is of particular significance, since it may be indicative of a spread of
the organism and the malady or an increase in the prevalence of conditions
conducive to it.

In the Bear River section of Great Salt Lake, Utah, one of the old-
est known points of infection, conditions in 1933, 1934, and 1935 showed
improvement over those prevailing when the disastrous outbreak of 1932 oc-
curred (see page 2). Although several thousand dead were found there dur-
ing each of the 3 years, this number reflected a relatively favorable con-
dition in this highly infected area, particularly in view of the fact that
extremely low water prevailed. In 1936 mortality increased, and a con-
servative estimate of the losses placed the total number of waterfowl
succumbing to botulism in the Salt Lake Valley at 50,000, about a fifth of
the toll of 1932. Birds died not only on the deltas of all three rivers
flowing into Great Salt Lake— the Jordan, the ::iear, and the Weber — but many
thousands perished at other points in the valley even as far south as Utah
Lake, which, from experiences of earlier years, had become known as a point
of infection.

In 1936 the Biological Survey and the Utah State Game and Fish De-
partment cooperated in an extensive program of salvaging disabled birds
and frightening healthy ones from infected areas. In 1937 the disease
again appeared in marked intensity at the northern end of Great Salt Lake,

and rescue op orations, facilitated "by both "field and base hospitals,"
effected the recovery of many hundreds of waterfowl. Several hundred
ducks, including many ducklings, perished on the shore of Utah Lake as a
result of an outbreak soon after the hatching season.

During the period 1933-37 botulism appeared in numerous localities
in California. If reliance can be placed on the estimates made of the
number of dead ducks' and shore birds observed, the outbreak late in the
summer of 1933 on the deltas of the New and Alamo Savers in the Imperial
Valley of California is outstanding. Oh some sections of the shore line
the dead lay at the rate of 800 to the linear mile, while estimates of
mortality throughout the season reached many thousands. This condition
recurred in this same area during the following spring, when death from
botulism was confined largely to migrating shore birds. At the other end
of California, at 'Sixth Lake in Siskiyou County, the disease had manifested
itself for several years, conditions conducive to it prevailing as late as
1937, when rescue operations were carried out. Despite this salvage, it
has been estimated that fully 7,000 birds perished that year. The sickness
also appeared at several points in the San Joaquin "Valley, the scene of
outbreaks almost since the beginning of the recorded history of this dis-
ease among waterfowl.

In adjacent areas of southern Oregon, or. the chores of Upper
Klamath Lake, botulism appeared in moderate intensity in the fall of 1934.
Although no estimate is available of the number that died, more than 1,000
ducks were brought to recovery pens. Many of these birds regained their
strength, were banded, and released. In 1937 for the first time in several
years, the sickness broke out in the region of Malheur Lake in southeastern
Oregon.

A locality in which botulism among' wild birds was recently discov-
ered is Red Lake on the Leupp Indian Agency about 50 miles north of Win-
slow, Ariz., where an epizootic, apparently of botulism, occurred in the
summer of 1933. The lake "bed had been dry for several years, but the dis-
ease developed when rains flooded part of it during the summer and early
fall of that year, and at least 5,000 ducks are believed to have perished.
Estimates m«de earlier in- the summer at the peak of tho- outbreak placed
the toll at a much higher figure.

In 1937, reports of botulism came from two points in New Mexico,
each representing an additional locality for the disease in that State.
At Cheap John Lake, Catron County, 600 to 1,900 ducks died in September
and October; while near La Joya, about 6 miles north of San Acacia in
Socorro County, several hundred succumbed in an area not far from where
mortality was reported. 10 years earlier.

In western Nebraska, where, during recent years, the number of in-
fection areas has apparently increased, botulism has appeared in moderate
intensity at several points. In 1933 many ducks died at Gay Lake and on
other bodies of water near Irwin, and at some of these more birds perished
the following year. At Skunk Lake., northeast of Alliance, dead ducks were
found, at the rate of 50 to the quarter mile of shore in September 1934,

_ 4 _

and in the same year fully 1,000 dead were reported at Lake Turcott, south-
east of Alliance. Likewise the death rate was high at Deer and Black Steer
Lakes, in the same general vicinity, as late as 1937.

In South Dakota, ducks died from "botulism at Sand Lake, near Columbia,
in 1935, and 2 years later the disease appeared at Lake Oakwood, in the
eastern part of the State. In neighboring North Dakota the malady was not-
ed at Upper Des Lacs Lake for the first time in 1934, when many hundreds of
"birds died presumably from feeding on decaying insects and other inverte-
brates washed up on the shoreline. About a thousand died there in 1935,
and in 1936 an outbreak occurring at the same lake resulted in the death of
more than 13,000 birds, a loss outnumbering the wild-fowl production of the
surrounding area for that season. Ailing birds were salvaged, and the bod-
ies of the dead were buried by crews of CCC boys, while the healthy ones
were herded out of the supposedly infected areas. Long Lake, southeast of
Bismarck, a scone of severe mortality in former years, again was the site
of an epizootic of moderate intensity in 1937.. .

Two apparently newly infected areas were recorded in Minnesota in
1937, when certain sloughs in Big Stone County and Lake Shoakatan, Lincoln
County, were the scenes of botulism outbreaks. "Many hundreds" were re-
ported to have died in these sections along the western border of the State.

In Canada

During the summer and early fall of 1933, it was estimated that
15,000 to 20,000 ducks and shore birds died at Stobart and Namaka Lakes,
about 40 miles southeast of Calgary, Alberta, points where there had been
no previous record of disease. At Stobart Lake sick birds were reported
in the middle of July by Blackfeet Indians, and the shore line was lit-
tered with dead by the first week in August. Low water, high temperatures,
and stagnation characterized the environment at the peak of the outbreak.
Leeches, in great abundance at Stobart Lake, fastened themselves on the
helpless birds and were considered by some observers to be the cause of
the ma.lady. At Namaka Lake, however, where the peak of a similar epizootic
came a little later, leeches were not plentiful. R. M. Duthie, veterin-
arian of the Dominion Department of Agriculture, who studied the situa-
tion late in the course of the outbreak, concluded that it Was "strongly
suggestive of a toxemia of some kind" and subsequently stated that, although
certain symptoms characteristic of the disease appeared to be absent,
botulism may have been the cause. The leeches, he felt, did not play a
primary role, although it v;as generally admitted that the extent of the
mortality may have been increased materially by the annelids attaching
themselves within the air passages and thus strangling the helpless birds.
At a later time (1936) Shaw and Simpson (3) demonstrated that the organism
responsible for the outbreak at Stobart Lake was identical with that which
had caused the extensive mortality in this country.

Again, in 1934, there was limited early-season mortality among
Franklin's gulls nesting at Stobart Lake, and later in the year botulism
reappeared among ducks when the water level had lowered considerably.

- 5 -

Between August 15 and September 15, 960 si ok birds were gathered and were
given wholesome living conditions; of these 72 percent recovered. The
waterfowl toll at Stobart Lake in 1934 was estimated at 5,000.

In 1933, 4,000 ducks were reported to nave died at Twelve Mile Lake,
near Bow Island, Alberta. Although no study was made of this outbreak,
the indications are that botulism was .the cause.

Of interest, because of its northerly location, is the mortality
among ducks reported by J. Dewey Soper, Chief Federal Migratory Bird Offi-
cer of the Prairie Provinces of Canada (4) . For some years vague reports
of dying ducks had come to Dominion officials from the Lake Claire Indians,
and during the summer of 1933 opportunity was afforded to search for and
locate the infected area. In that season it was found to be on the shores
of a body of water north of TCelstead Lake, at a point v/est of Lake Atha-
basca. Although the mortality was not extensive and bacteriological proof
of its cause was lacking, conditions typical of those conducive to bot-
ulism prevailed. Should this outbreak have, in fact, been botulism, and
Mr. Soper believes it was. it constitutes the most northerly occurrence of
the disease among wild birds of which the writer has knowledge — 58° 30'
north latitude.

Mention may be made of excessive death rate among Franklin.1 s gulls
on the Delta Marsh at the south end of take Manitoba in June 1934. Bed-
heads, ruddy ducks, and coots also were affected.. There is no conclusive
evidence of the cause of the disease, yet it occurred during a period of
high temperature and in an environment where a lowered water level had
exposed extensive mud flats. These circumstances, together with the fact
that the water of Lake Manitoba is somewhat alkaline, are suggestive. This
area likewise lies directly north of points in the Dakotas where botulism
is known to have occurred. In 1937 newspapers recorded the death of ad-
ditional hundreds of waterfowl in the same area..

In Australia

A recital of recent manifestations of botulism among wild birds
would be incomplete without mention of the noteworthy discoveries made in
Australia by E. Murray Pullar in 1934 (-2). Not only do Pullar's findings
reveal that botulism is a threat agairst the well-being of wild fowl even
on that distant island continent, but they lend a measure of corroboration
to the discoveries made in this country (1).

During the Australian summer of 1931-32 botulism was reported at
four points in northern and western Victoria. All the outbreaks were
associated with hot, dry weather (shade temperature being 95° to 110° F.),
low water, and an abundance of rotting vegetation. Hundreds of birds died
under conditions strongly suggestive of epizootics that have occurred in
the western United States. In the following summer (1932-33) a severe
outbreak occurred at the Hume Reservoir, along the Murray River, where
the deep mud, rotting vegetation, and decaying bodies afforded an excel-
lent medium for the causative organism.

- 6 -

Of particular interest to "bacteriologists are Pullar' s conclusions
regarding the identity of the organism causing the Australian sickness.
This he; found to he Clostridium parabotulinum ( Seddon) , which, as inter-
preted "by American research workers in this field, is considered to he
simply a closely related variant of the organism responsible for outbreaks
among wild ducks on this continent, C. botulinum type C

Although Pullar states that the Australian disease does not always
appear to he associated with alkaline waters, he apparently had in mind
waters of a high saline content, since he f ound that the water of the Hume
Reservoir possessed an alkaline pH of 7.6, while those at other points of
infection were even brackish. As nointed out hy the American workers (l),
moderate alkalinity appears to he highly favorable, perhaps a prerequisite,
for the well-heirg of the causative organism, while excessive alkalinity or
high concentrations of salines may destroy the toxin or inhibit growth of
the bacterium.

SAFEGUARDS FOB. THE FUTURE

With events in Australia paralleling somewhat the. course of early
ones in North America, certain questions arise concerning the possible
future course of "botulism among waterfowl. Are added extensions of the
range of this malady to he expected not only in North America and possihly
South America, hut also in Australia? Is this to become a world-wide plague
and a threat to wild fowl wherever they are unable to find wholesome living
conditions? Is the organism itself undergoing a "period of ascendancy," or
ar© man-made conditions working to its advantage? In the United States
many workers believe that man-made conditions have had much to do with the
course of events in the West during the past two decades and that a restor-
ation of wholesome, adequate, and stable water supplies will go far toward
remedying the deplorable condition.

Tims the engineer often must he called upon to stand shoulder to
shoulder with the naturalist and conservationist if future catastrophes,
which will destroy added thousands of western wild fowl, are to he pre-
vented. The preservation of these remaining birds is dependent not only
on the creation of adequate breeding grounds (and no one questions the
grave necessity of this) . hut the birds raised there must also be provided
with paths, of migration reasonably free. from, an over- re earring scourge,
that has taken a toll of millions. The two must go hand in hand. Unless
this can he assured, the "best efforts to restore "breeding grounds for wild
fowl may, in some years, be largely nullified.

With present knowledge of measures for combating the ravages of
botulism among wild fowl and with the relatively limited means available
for actually carrying out programs of prevention or rescue, the fact re-
mains that for years to come many waterfowl are destined, to perish without
the possibility of human intervention in their behalf. Despite the ex-
tensive efforts being made to restore wholesome habitat:;,, it will he utterly
Impossible in many areas and at many times to prevent sudden and unex-
pected onslaughts of this sickness. Until methods and finances permit a
more effective control of this disease than is now possible, sportsmen
also mast realize that here is a natural and often unpreventable drain on
wild fowl that apparently did not exist in equal intensity in earlier days.

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UNIVERSITY OF FLORIDA

3 1262 08928 0068

Until these losses can "be curbed-, it behooves every duck hunter to bear
in mind that the toll of even a single gun may be important it. those western
areas where the malady strikes with devastating effect. The assertion, heard
all too frequently at such tiiaevsy that "what we shoot is nothing compared
with the loss from disease," though true locally, cannot be entertained as a
palliative for increased shooting privileges. It is conceivable that as a
result of serious outbreaks, as have at times occurred in the Salt Lake Valley,
the breeding stock of Considerable regiors, as we31 as a lerge part of the
waterfowl produced, may be nearly wiped out. Such outbreaks cannot be pre-
dicted with certainty, but when they do appear, sound management practices
as well as good sportsmanship calls for a zealous conserving of ev^ry indi-
vidual that can be saved or is fortunate enough to escape the ravages of the
disease.

LI TERATUHE CITED

(1) Kalmbach, E. H.

1934, Western duck sickness, a form of- botulism; with bacteriological
contributions by Millard E. Gunderson. U. S. Dept. Agr.
Tech. Bull. 411, 81pp., illus.

(2) Pullar, I. M.

1934. Enzootic botulism amongst wild birds. Aust . Vet. Jour. 10 ( 4),

128-135, illus. August.

(3) Shaw, H. If. , and Simpson, G. S.

1935. Clostridium botulinum, type C, in relation to duck sickness in

the Province of Alberta. Jour. Bact. 32: 79-88.

(4) Soper, J. Dewey

1934. A waterfowl r jconnaissance of Wood Buffalo Park . Trans.
Twentieth Amer. Game Conf . 1934: 258-265.

(5) wetmore, A-

1918. The duck sickness in Utah. U. S. Dept. Agr. Lull. 672, 26 pp.,
i llus .