Zoologica : scientific contributions of the New York Zoological Society

ZOOLOGICA

SCIENTIFIC CONTRIBUTIONS OF THE
NEW YORK ZOOLOGICAL SOCIETY

VOLUME 58 • ISSUE 2 • SUMMER 1973

PUBLISHED BY THE SOCIETY
The ZOOLOGICAL PARK, New York

NEW YORK ZOOLOGICAL SOCIETY

The Zoological Park, Bronx, N. Y. 10460

Laurance S. Rockefeller
Chairman, Board of Trustees
Robert G. Goelet
President

Howard Phipps, Jr.

Chairman, Executive Committee
Henry Clay Frick, II
Vice-President
George F. Baker, Jr.

Vice-President
Charles W. Nichols, Jr.

Vice-President
John Pierrepont
Treasurer
Augustus G. Paine
Secretary

William G. Conway
General Director

ZOOLOGICAL PARK

William G. Conway, Director & Chairman, Dept, of
Ornithology ; Joseph Bell, Curator, Ornithology ;
Donald F. Bruning, Associate Curator, Ornithology;
Hugh B. House, Curator, Mammalogy; James G.
Doherty, Associate Curator, Mammalogy; F. Wayne
King, Curator, Herpetology; John L. Behler,
Assistant Curator, Herpetology ; Joseph A. Davis,
Scientific Assistant to the Director; Walter
Auffenberg, Research Associate in Herpetology;
William Bridges, Curator of Publications Emeritus;
Grace Davall, Curator Emeritus

AQUARIUM

James A. Oliver, Director; George D. Ruggicri, S.J..
Associate Director; William S. Flynn, Curator;

H. Douglas Kemper, A ssociate Curator; Christopher
W. Coates, Director Emeritus; Louis Mowbray,
Research Associate, Field Biology

OSBORN LABORATORIES OF
MARINE SCIENCES

George D. Ruggieri, S.J., Director & Experimental
Embryologist; Ross F. Nigrelli, Senior Scientist;

Martin F. Stempien, Jr., Assistant to the Director &
Bio-Organic Chemist; Jack T. Cecil, Virologist; Paul
J. Cheung, Microbiologist; Joginder S. Chib,

Chemist ; Kenneth Gold, Marine Ecologist; Myron
Jacobs, Neuroanatomist; Klaus D. Kallman, Fish
Geneticist; Kathryn S. Pokorny, Electron Microscopist;
Eli D. Goldsmith, Scientific Consultant; Erwin J.

Ernst, Research Associate, Estuarine & Coastal
Ecology; Martin F. Schreibman, Research
Associate, Fish Endocrinology

CENTER FOR FIELD BIOLOGY
AND CONSERVATION

George Schaller, Research Zoologist & Co-ordinator;
Thomas Struhsaker, Roger Payne, Research
Zoologists; Donald F. Bruning, Research Associate

ANIMAL HEALTH

Emil P. Dolensek, Veterinarian; Consultants:

John Budinger, Pathology; Ben Sheffy, Nutrition;
Gary L. Rumsey, Avian Nutrition; Kendall L.
Dodge, Ruminant Nutrition; Robert Byck,
Pharmacology; Jacques B. Wallach, Clinical
Pathology; Edward Garner, Dennis F. Craston,
Ralph Stebel, Joseph Conetta, Comparative
Pathology & Toxicology; Harold S. Goldman,
Radiology; Roy Bellhorn, Paul Henkind, Alan
Friedman, Comparative Ophthalmology; Lucy
Clausen, Parasitology; Jay Hyman, Aquatic
Mammal Medicine; Theodore Kazimiroff, Dentistry;
Alan Belson, Resident in Pathology

Z00L0GICA STAFF

Simon Dresner, Editor & Curator,
Publications and Public Relations
Joan Van Haasteren, Associate Editor
& Assistant Curator, Publications &
Public Relations

Louise A. Purrett, Assistant Editor &
Feature Writer
F. Wayne King
Scientific Editor

AAZPA SCIENTIFIC ADVISORY COMMITTEE

lngeborg Poglayen, Louisville (Kentucky)
Zoological Gardens, Chairman; William G.
Conway, New York Zoological Society; Gordon
Hubbell, Crandon Park Zoo, Miami; F. Wayne
King, New York Zoological Society; John
Mehrtens, Columbia (South Carolina) Zoological
Park; Gunter Voss, Metro Toronto Zoo, Canada

© 1973 New York Zoological Society.
All rights reserved.

3

Some Observations on the Growth of Captive Alligators

(Figures 1-2)

Thomas D. Coulson

Department of Pharmacology, Louisiana State University Medical Center,

New Orleans, Louisiana 70112

Roland A. Coulson

Department of Biochemistry, Louisiana State University Medical Center,

New Orleans, Louisiana 70112

Thomas Hernandez

Department of Pharmacology, Louisiana State University Medical Center,

New Orleans, Louisiana 70112

Alligators collected in Louisiana coastal regions immediately after hatching were kept in
outdoor concrete tanks at about 30°C for periods as long as two years. They were fed ground
marine fish on five or more days of each week in all seasons of the year. They grew rapidly
reaching lengths of three feet in one year and almost five feet in two years, and they outweighed
severalfold wild alligators of the same age. Their mortality rate was only a fraction of that
estimated for comparable wild alligators. It appears that use of “brooders” is a practical (and
inexpensive) means of restocking depleted areas.

Introduction

A continuing demand for hides and in-
creased drainage for land reclamation
threatens many species of crocodilia with
extinction. Where conservation is practiced, it
involves prohibiting killing animals of any size, or
of those below a certain body length. The results
of these measures have not been encouraging, as
sufficient funds have rarely been made available
to provide enough men to police the waterways
and swamps, terrain that provides concealment
for the poacher.

Although attempts to increase the population
by establishing breeding colonies have not been
very successful in the past, encouraging results
have been obtained recently (Youngprapakorn,
Cronin, and McNeely, 1971) and it is to be hoped
that such methods will eventually permit restock-
ing areas depleted by hunters and hide collectors.
In the interim, a system whereby newly-hatched
crocodilians are taken from the nest and raised in
compounds for future release may offer promise
for immediate relief. Crocodilians, almost helpless
at birth, have few natural enemies when they have
reached a body length of three feet or more
(Mcllhenny, 1935).

The following account records some of the
observations derived from several years of
experience on the growing of young alligators in
captivity.

Materials and Methods

Over a period of several years some 600 alliga-
tors were obtained from the Louisiana Wildlife
and Fisheries refuge at Grand Cheniere, Louisi-
ana, through the cooperation of Ted Joannen and
Allan Ensminger. Those used in the first year
growth experiments were first fed on September 1 5.
At the conclusion of the growth studies, all were
returned to the swamps by agents of Wildlife and
Fisheries.

Alligator Tanks

The outdoor tanks for housing the newly
hatched animals were about 1.5 meters long by 0.6
meter deep by 0.75 meter wide, with a 5 cm drain
placed at each end at the bottom of a gentle slope.
They were of smoothed concrete about 5 cm thick
covered with a “press-metal” diamond shaped
mesh of about 2.5 cm holes. In winter the tops were
covered with ultra-violet transmitting thin poly-
ethylene sheets which also reduced evaporation
and conserved heat. Although all tanks were ex-

47

48

New York Zoological Society: Zoologica, Summer, 1973

posed to direct sunlight in the winter, a tall stand
of banana “trees” shaded them from the late after-
noon sun in the summer. Each tank was equipped
with a 500 watt immersion heater and the amount
of heat delivered was controlled by a heavy-duty
“power-stat” from inside the laboratory. The total
heating capacity at its maximum was sufficient to
maintain a 25 cm water depth at 30°C, except in
very cold weather (below 5°C) when water temper-
atures as low as 23°C were recorded. Although
this was not entirely satisfactory, inadequate
heating at the New Orleans site (Pitcher Plaza,
Louisiana State University Medical Center) was
experienced at scattered periods for no more than
20 days in the year.

Water was changed about three times a week.
Those tanks housing alligators under one year of
age were provided with a two-foot square plywood
platform for basking, which cleared the surface by
less than two cm. Food was placed on the plat-
forms and it was necessary for the animals to leave
the water to feed. Larger alligators (up to 150 cm),
which were not provided with areas for basking,
did not appear to suffer from being forced to
remain in the water for months at a time.

Food

The diet consisted solely of marine fish, fed
whole to the large alligators, and ground coarsely
(bones, scales, and all) for the smaller ones. The
fish were obtained from a local wholesale fish
dealer (Louis Cognevitch) and the following is
roughly the ratio of the contributions of the
various species fed: southern kingfish ( Menticir -
rhus americanus ), 55 percent; Atlantic croaker
( Micropogon undulatus ), 15 percent; spotted sea-
trout ( Cynoscion nebulosus), 10 percent; and from
1 to 4 percent of striped mullet (Mugil cephalus),
red snapper (Lutianus campechanus), and black
drum (Pogonias cromis). The remainder repre-
sented at least a score of other species. Since the
fish were marine in origin, they probably contained
significant amounts of vitamin D, although the
availability of ultraviolet from sunlight may well
have rendered dietary vitamin D unnecessary. For
the small alligators (during the first year after
hatching), food was supplied ad lib. For those
beyond one year of age, feedings were restricted
in the winter to two or three times a week. No
vitamin supplements were given.

The total quantity of fish consumed was esti-
mated by weighing the fish placed in the tank,
followed by weighing the amount remaining in the
tank the next day. The uneaten portion was then
removed, and once again an excess of weighed
fresh fish was added, etc.

Results

Relationship Between Length and Body Weight

Total body length measurements and weights
may be determined with ease on alligators that are

below 180 cm in length. Beyond that size lengths
may be measured easily, but body weights are diffi-
cult to determine and most of those reported are
suspect. Length-weight relationships on several
species of crocodilia were reported by Dowling
Brazaitis (1966), but the actual number of indi-
viduals measured seems to have been small. In
view of the paucity of knowledge, several hundred
alligators of various sizes were weighed and the
total body lengths were determined. All of these
animals had been kept in the outdoor tanks and
pens for some time, and they had been well fed for
considerable periods. Although heavier than wild
alligators taken from the South Louisiana
marshes, they did not appear grossly corpulent.
The relationship between total length and body
weight of some of these captive alligators is shown
in Figure I. Specimens below 120 cm in length
were so numerous that the points ran together and
many were therefore omitted.

The observed slope of the curve corresponded
to the points marked with an X. The relationship
may be expressed in the form of a straight line by
plotting the log,,, of the weight in kg against the
login °f the total length in cm. J. D. Herbert (per-
sonal communication, 1971) derived a formula
which seems to apply to all alligators from those
newly hatched to those several meters long.
Y = ax + b (the equation for a straight line) appears
to apply if y = log,0 of the weight in kg, a = 3.35,
x = log10 of the length in cm, and b = -6.10. Not
enough information is available to verify the equa-
tion for alligators beyond three meters length, but
a few reports of length-weight measurements on
specimens beyond three meters (Dowling and
Brazaitis, 1966) suggest that the formula may
apply to all sizes. If it does apply, a well nourished
six-foot (183 cm) alligator would weigh 30 kg, a
seven-footer (213 cm) 50 kg, an eight-footer (244
cm) 79 kg, a nine-footer (274 cm) 1 17 kg, a ten-
footer (304 cm) 168 kg, an eleven-footer (335 cm)
229 kg, etc.

The Factor of Temperature

Although alligators inhabit a region which is
largely sub-tropical, it appears they need very high
temperatures for satisfactory growth and physio-
logical function (Brattstrom, 1965). If they were
exposed to the comparatively mild temperatures
of I8°C (65° F) some impairment of renal function
occurred (Coulson and Hernandez, 1964). A
normal alligator excretes massive amounts of
NH4HCO, which serves two functions, salt reten-
tion and nitrogen excretion. At temperatures
below 18°C, the ability to synthesize NH4HCO3
was reduced and as a consequence, NaCl was lost
to the urine (Hernandez and Coulson, 1957). In
addition to the renal effects, desire for food was
diminished or absent at temperatures below 22°C
regardless of the season. From the results of a pro-
longed series of experiments, it appeared that tem-
peratures between 29°C and 31°C were best for

Coulson, Coulson, <& Hernandez: Observations on Growth of Captive Alligators

49

Figure I. Relationship between total length and body weight in alligators up to 180 cm in length.
Each dot represents a single specimen. The X’s represent the apparent average. J. Herbert (personal
communication, 1971) derived a convenient expression from the data which appears to be useful for
all alligators from the smallest to the largest. The formula y = ax + b, the equation for a straight
line, applies if y = log,0 of the weight in kilograms, a = 3.35, x = log,,, of the length in centimeters, and
b = -6.10. Although reliable data on wild specimens is scarce, it is probable that the somewhat
thinner wild alligators would conform to a weight-length curve shifted to the right of the one above.

50

New York Zoological Society: Zoo/ogica, Summer , 1973

the alligator even in winter. High temperatures
also facilitated the absorption of the yolk sac, a
factor that appeared responsible for reducing the
reported high mortality rate (Joannen, personal
communication, 1971) to below 10 percent. Those
kept at cooler temperatures retained the yolk sac
for months, and a high percentage developed an
abdominal tumor of sufficient size to prevent food
from entering the stomach.

Growth Rates

The growth rates of alligators in these experi-
ments (Figure 2) were far greater than those re-
ported for wild alligators (Mcllhenny, 1935). The
curve was drawn from the median weights and
lengths of about 200 small alligators for the first
year and from about 25 for the second year. Some
10 percent of each group of new-hatched alligators
that were received failed to grow appreciably.

In all visible respects, the year-old alligators were
in excellent health, their skins were unmarred, their
teeth were straight, and they resembled wild
alligators twice their age, except for the fact that the
captive animals were heavier. The two-year-old
captive alligators were as long as local wild
alligators at four-and-one-half years (Mcllhenny,
1935) and about 10 percent heavier for their length.

Food Consumption

The food consumed was determined for scores of
alligators of various ages and weights over a period
of several years. The smallest alligators converted
over 40 percent of the weight of the food eaten into
body mass, and those alligators from one year to
three years of age converted about 25 percent. The
average cost for an alligator for the first year after
hatching was about 55 cents, and for the second
year, about $3.50 (calculated on the basis of five
cents a pound for fish).

Protrusion of the Cloaca

Large alligators (over five feet in length) that
were being fed at a maximal rate occasionally
developed a disorder of the cloaca in which the
entire region protruded ventrally by as much as two
inches. The disorder appeared to be the result of
pressure in the abdominal area caused by chronic
engorgement or by deposition of fat around the
cloaca. Abrasion of the lesion led to bleeding when
the animals were on dry concrete a good part of the
day, but if they were fasted and forced to remain in
water, the condition improved in a few days and no
permanent damage resulted.

Parasites

Most large alligators caught in the wild suffer
from intestinal parasites, usually round worms.
Infected animals were usually very lean and some
refused food for months. This problem was not
serious in the captive animals and the parasites
disappeared within a few months, if the absence of
round worms in the fecal matter was an indication.
Although no study was made of the types of

parasites in the wild specimens or of their incidence
in the captive animal’s intestines, it was our
impression that parasitism did not limit growth
under the conditions reported here. No attempts
were made to treat the infected animals with
antihelminth drugs.

Imported caimans (Caiman crocodilus croco-
dilus ) are infested with worms, and the mortality
rate of the small ones is very high even when kept
under the same conditions as the small alligators.
The possibility that imported caimans could infect
the alligators was a problem of concern; however,
there was no evidence that this occurred.

Gout

This classical disease of man had been reported
in “alligator, species unknown,” (Appleby and
Siller, 1960), but the article did not state whether
the animal was captive or wild. In the early years of
the growth studies, this disorder occasionally
proved a problem in the well-fed captive alligators.
If an alligator is in a period of rapid growth, most of
the nitrogen ingested is converted quickly into
body protein and the amount excreted is not
beyond the capacity of the kidneys. On the other
hand, if an alligator is accustomed to daily
feedings, it is possible for it to ingest protein and
digest it faster than it can remove the amino acids
by the route of protein synthesis. The unused
ammo acids pass their nitrogen to ammonia
formed in the kidney and to uric acid synthesized in
the liver (Coulson and Hernandez, 1964). When
they were “overfed” for a long period, uric acid was
deposited in the joints, over the sternum, and
eventually in the soft tissues in massive amounts.
Paralysis occurred first in the front legs and later in
the back legs, and death resulted apparently from
damage to the kidneys which were packed with
urates. The problem was most severe in winter, at a
time when the growth rate was the lowest. If the
alligators were fasted for a week or so after the
appearance of the first signs of paralysis, all
recovered quickly and the regular feedings were
resumed. Fortunately, alligators under a year of
age were not as prone to develop the disease and
food restriction was seldom necessary. When the
nature of the problem was understood, no further
deaths occurred from gout. Aside from a few
“infant mortality” deaths in the first few weeks after
hatching, there have been no deaths from any cause
in an average population of 100 alligators in the
past three years.

Discussion

Alligators are carnivorous. In their natural
habitat, small ones eat insects, crayfish, small fish,
frogs, etc., and large ones eat fish, rodents, and
other small mammals, snakes, turtles, birds, in-
sects, and assorted crustaceans. Since turtles are an
important item of the diet, it is evident that
alligators are accustomed and prepared to handle

BODY WEIGHT IN KILOGRAMS

Coulson, Coulson & Hernandez: Observations on Growth of Captive Alligators

51

BODY LENGTH IN CENTIMETERS

Figure 2. Weights and total body lengths of captive small alligators over a two-year period. The
data for the first year were derived from the median weights and lengths of about 200 alligators, and
that for the second year from 25 alligators. The median weights of the two-year-old captive alligators
were about 14 times that of wild specimens of the same age ( Mcllhenny, 1935).

52

New York Zoological Society: Zoologica, Summer, 1973

large amounts of bone. The problem of digestion is
apparent if one considers the nature of the shell of
the common slider turtle ( Chrysemys scripta ), one
of the favorite foods (personal observation). In
defense against the mechanical problems involved,
the stomach is a powerful organ, and the lumen is
supplied with more hydrochloric acid than is found
in any other known animal (Coulson, Hernandez
and Dessauer, 1950). Almost all of the calcium and
phosphate of the bone is excreted by way of the gut,
and when alligators receive a natural diet, the feces
are almost entirely calcium phosphates and car-
bonates (Coulson and Hernandez, 1964). It would
be logical to assume that in any captive colony large
amounts of bone should be supplied in the food.
Deficiencies of calcium phosphate and vitamin D
in the diets of alligators kept in the laboratory or as
household pets often lead to the development of
severe rickets characterized by misshapen limbs
and a curious shortening of the head (personal
observation).

The cost and availability of chicken necks has
led to their widespread use for alligator food by
roadside exhibitors. This may not be in the best
interest of the alligators, since most chickens pro-
duced commercially have received the synthetic
female sex hormone, stilbesterol. The possibility
of hormonal sterilization should be considered.

The Rate of Growth

It is of course not possible to state what the rate
of growth would be under “ideal” conditions. Alli-
gators in the wild grow at rates determined by such
factors as the temperature of the water and of the
air, the hours of sunshine, and the amount and
type of food available. It has been stated that small
wild alligators grow about a foot a year for five
years and somewhat more slowly thereafter (Mc-
llhenny, 1935). Those taken from the wildlife ref-
uges in coastal Louisiana grow little from the time
of hatching to spring, picking up rapidly in June,
and tapering off again in October. From Novem-
ber to April, they are said to be “hibernating,”
although in the true sense they do not hibernate
as their metabolic rate is the same in winter and
summer if the temperature is constant (Hernandez
and Coulson, 1952). However, growth and the
natural appetite associated with it is not dependent
entirely on temperature, and alligators will not
grow as fast in winter as in summer (Figure 2) at
the latitude of New Orleans (30°N). It would be of
interest to follow the growth rates of alligators kept
in equatorial latitudes, and at least one such exper-
iment is under way (T. Joannen and A. Ensminger,
1971, personal communication).

Fortunately, our alligators were able to stand
considerable crowding without apparent adverse
effects on growth rates, a factor of importance
when the cost of housing facilities is considered.
An area of 600 square feet, half with water and half
dry, is sufficient to house and feed about 5,000
alligators from the time of hatching to one year of

age. In the second year, at least ten times as much
space would be needed for the same number of
animals.

Unanswered Questions

The fact that one can grow alligators in captivity
at a great rate does not mean that one can neces-
sarily reduce the time required for the develop-
ment of breeding stock. Wild egg-laying females
are beyond five or six feet in length, but we do not
know whether they must also be over five or six
years old. If size is the sole determinant of breeding
capacity, three-year-old captive alligators would
be more than large enough; if age is the determi-
nant, domestic females would be full-grown by the
time they can breed.

Of the hundreds of alligators housed at the Lou-
isiana State University unit over the years, males
have exceeded females by better than three to one.
Others have commented on this phenomenon as it
seems to be true for crocodilians generally.

Literature Cited
Appleby, E. C., and W.G. Siller

I960. Some cases of gout in reptiles. J. Path. Bact.,
80: 427-430.

Brattstrom, B. H.

1965. Body temperature of reptiles. Amer. Midi.
Natur., 73(2): 376-422.

Coulson, R.A., T. Hernandez, and H.C. Dessauer
1950. Alkaline tide of the alligator. Proc. Soc. Exptl.
Biol. Med., 74: 866-869.

Coulson, R. A., and T. Hernandez

1964. Biochemistry of the alligator: a study of metab-
olism in slow motion. Louisiana State Univ.
Press, Baton Rouge, La.

Dowling, H.G., and P. Brazaitis

1966. Size and growth in captive crocodilians. Int.
Zoo Yearbook, 6: 265-270.

Hernandez, T„ and R. A. Coulson

1952. Hibernation in the alligator. Proc. Soc. Exptl.
Biol. Med., 79: 145-149.

1957. Inhibition of renal tubular function by cold.
Am. J. Physiol., 188: 485-489.

McIlhenny, E. A.

1935. The alligator’s life history. The Christopher’s
Publishing House, Boston.

Youngprapakorn, U., E. W. Cronin, and
J. A. McNealy

1971. Captive breeding of crocodiles in Thailand. In
Crocodiles. Intern. Union Conserv. Nat. Publ.
New Series, Suppl. Pap. 32. pp. 98-101.

NEWS AND NOTES

%

Some Observations on the Maned Wolf,
Chrysocyon brachyurus , in Paraguay1

During the spring of 1972, while investigating
two species of armadillo under a grant from the
American Philosophical Society (Philadelphia),
several facts regarding the maned wolf (Chryso-
cyon brachyurus) and its status in Paraguay were
obtained.

Adults rarely appear on the animal market in
Asuncion. Exporters know from experience that
adult animals rarely acclimate to their captive
conditions and they generally refuse those adults
brought in by trappers. As a consequence, trappers
prefer to capture pups and young wolves. These
appear on the animal market during November,
December, and January.

Five animals were exported from Asuncion in
1970-71. One shipment contained three animals
destined for Europe; the status of these specimens
is unknown at present. Early in 1972, several sub-
adults were purchased by a dealer in Asuncion (El.
Stellfeld, personal communication). All arrived
at the dealers in severely debilitated condition,
refused to feed and died before exportation could
be accomplished. These animals were originally
destined for European zoos. Since that time, one
export of this species occurred from one of Asun-
cions’ five animal dealers (P. Rodriegez, personal
communication; and M. Elauptman and E. Koopf-
man, personal communication). This animal was
seized at Miami, Florida, by federal authorities.
It too was severely debilitated and died almost
immediately.

Not infrequently, maned wolves are captured
in the northern Argentina provinces of Chaco and
Formosa, and are brought to Asuncion for sale
and export to foreign zoos. Elowever, the majority
of the maned wolves offered for sale in Asuncion
are true Paraguayan animals.

The only restriction now applied to the exporta-
tion of this species from Paraguay is a health cer-
tificate issued by the Departmento de Accion y
Control Pecuario of the Ministeriode Agricultura
y Ganaderia. This however, is a formality and can
be obtained without difficulty by the resident
exporters. There is an indication that in the near
future restrictions will be forthcoming to drasti-

1 This work was supported in part by a grant from
The Johnson Fund of the American Philosophical
Society ( Philadelphia).

cally limit the number of mammal exports in gen-
eral (P. Rodriegez, personal communication).
These restrictions, if put into effect could further
restrict the number of maned wolves offered for
sale to exporters in Asuncion.

There is an extremely high incidence of internal
parasitism in most wild-caught maned wolves
(Matera, Saliba, and Matera, 1968). It appears
that disease rather than man or his continued land
use may be the single greatest detrimental force
acting on wild populations of the maned wolf in
Paraguay. The maned wolf is not hunted for meat
or fur by local people but may be the occasional
target of some hunter for lack of better game. Its
pelts are not offered for sale on the fur market in
Paraguay while the skins of most other carnivores,
such as puma ( Felis concolor ), jaguar ( Felis onca ),
ocelot (Felis pardalis ), and Geoffroy’s cat (Onci-
felis geoffroyi) are usually available.

There are no current studies under way on the
status of wild maned wolve^ in Paraguay, and
there are no reliable figures available regarding
actual numbers in the wild. It appears that there
are no areas of concentration of this species but
rather that the animals range is broken and dis-
continuous. When sightings are made of more
than one wolf at a time, it is usually an adult female
with offspring. This species is not known to travel
in groups. Several weeks spent by the author in the
habitat of this species in Paraguay revealed no
actual sightings of this species, only several-day-
old foot imprints in soft soil. In all cases these
appeared to be adult animals that were on the
move.

Literature Cited

Matera, E. A.. A. M. Saliba, and A. Matera

1968. The occurrence of dioctophymiasis in the
maned wolf, Chrysocyon brachyurus. In Int.
Zoo Yearbook, 8: 24-27.

Dennis A. Meritt, Jr., Lincoln Park Zoological
Gardens, Chicago, Illinois 60614.

53

Scent Marking in the Red Brocket, Mazama americana

(Figure 1)

Male roe deer have long been known to possess
a specialized scent gland, containing both
sudoriferous and sebaceous glands, on the
forehead (Schumacher, 1936). They frequently
mark with this gland during the rutting season
by rubbing it against vegetation (Kurt, 1968).
Recently, forehead-rubbing as a means of scent
deposition was described for the first time in a New
World cervid, the blacktailed deer, Odocoileus
heminous columbianus ( Miiller-Schwarze, 1971).
This species does not possess a forehead scent-
gland visible to the naked eye, but histological
investigation revealed that the sudoriferous glands
on the forehead are well developed (Quay and
Miiller-Schwarze, 1970).

We have observed forehead-rubbing in a second
New World cervid, the red brocket, Mazama
americana. One of us (N.V.) studied a captive
group of four male and three female brockets at
the New York Zoological Park (Bronx Zoo) for
15 hours. The deer were easily recognized in-
dividually on the basis of physical characteristics.
They were observed in a 30 by 6 meter enclosure
with a dirt substrate, small patches of grass
scattered about, and a large tree in one corner.

Three of the four males displayed forehead-
rubbing. The male which did not display had
antlers in velvet during the period of observation
(January to April, 1972). The males marked four
objects: a root of the tree, a small branch lying
on the ground, a branch of a tree sticking through
the fence of the enclosure, and one spot on the
fence itself. The male typically approached the
object to be marked, sniffed it thoroughly, licked
it several times, and then rubbed his forehead on
it (Figure 1). This behavioral sequence was some-
times repeated two or three times. The deer then
walked away and sometimes urinated nearby.
Sometimes a male sniffed or stood close to one
of the branches but did not rub on it. We never
saw a female brocket forehead-rub, although
female blacktailed deer do (Miiller-Schwarze,
1971; 1972). Two females did sniff objects which
males had forehead-rubbed.

In a group of four captive male blacktailed deer,
the frequency of forehead-rubbing by individuals
was positively correlated with the frequency with
which they won agonistic encounters, and the
behavior may be a means of agonistic interaction
in addition to threatening, chasing, and fighting
(Miiller-Schwarze, 1972). We did not observe
enough agonistic behavior in the brockets to
judge whether or not dominant males did more
forehead-rubbing. A correlation between a
high frequency of scent marking and high social

rank and between marking and aggressive
behavior patterns has been found in many other
mammals (Ralls, 1971).

Forehead-rubbing may well be found to occur
in many species of Odocoilenae in addition to the
roe deer, the blacktailed deer, and the red brocket.
The forehead skin of the brocket has not been
studied histologically, but probably contains
sudoriferous glands similar to those of the black-
tailed deer. Areas of well-developed sudoriferous
or sebaceous glands are probably more common
in mammals than generally recognized and may
well be equally as important in their chemical
communication systems as the better known
macroscopically visible scent glands.

Both male and female brockets urinated fre-
quently in small quantities in specific areas of the
enclosure. They sniffed a urination area, lip-
curled, and then urinated. Two hours after
the deer had been let outside into the enclosure,
the urination sites were easily visible as dark
spots on the ground. The smell of brocket urine
is pungent and quite noticeable to a human.
On one occasion the deer urinated 56 times in a
two-and-one-half-hour period. It is probable that
chemical signals in the urine are important in the
social life of brockets.

Red brockets have small or rudimentary tarsal
glands (Frechkop, 1955) and were not seen to
urinate on them while rubbing them together as do
blacktailed deer (Miiller-Schwarze, 1971).

We thank Dr. D. Muller-Schwarze for critical
reading of the manuscript and helpful suggestions.

Literature Cited

Frechkop, S.

1955. Sous-orde des ruminants ou selenodontes.
Pp. 568-693 in Traite' de Zoologie (P.-P.
Grasse, ed.). Vol. 17, Masson et Cie, Paris.

Kurt, F.

1968. Das Sozialverhalten des Rehes, Capreolus
capreolus capreolus L. eine Feldstudie.
Mammalia Depicta., Paul Parey, Hamburg,

102 pp.

Mulller-Schwarze, D.

1971. Pheromones in blacktailed deer. Anim.
Behav. 19: 19: 141-152.

1972. Social significance of forehead rubbing in
blacktailed deer (Odocoileus hemionus
columbianus). Anim. Behav. 20: 788-797.

Quay, W. B., and D. Muller-Schwarze

1970. Functional histology of integumentary gland-
ular regions in blacktailed deer (Odocoileus

55

56

New York Zoological Society: Zoologica, Summer, 1973

hemionus columbianus). J. Mamm. 51: 675-
694.

Ralls, K.

1971. Mammalian scent marking. Science 171: 443-
449.

Schumacher, S.

1936. Das .Stirnorgan des Rehbockes (Capreolus
capreolus capreolus L.), ein bisher un-

bekanntes Duftorgan. J. Mikr-anat. Forsch.
39: 2 1 5-230.

Nicholas Volkman and Katherine Ralls,
Sarah Lawrence College, Bronxville, New York
10708, and the Rockefeller University, New York,
New York 10021.

New York Zoological Society: Zoologica, Summer, 1973

Figure 1. Male red brocket forehead-rubbing on a small branch lying on the ground.

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Contents

PAGE

3. Some Observations on the Growth of Captive Alligators. By Thomas D.
Coulson, Roland A. Coulson, and Thomas Hernandez. Figures 1-2... 47

News and notes:

Some Observations on the Maned Wolf, Chrysocyon brachyurus, in
Paraguay. By Dennis A. Meritt, Jr 53

Scent Marking in the Red Brocket, Mazama americana. By Nicholas
Volkman and Katherine Ralls. Figure 1 55

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Published October 18, 1973