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National Zoological Park

Washington, D.C. 20009

Phones:

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FONZ Board of Directors 1972-1973

Peter C. Andrews, President

Theodore Babbitt

Amy Block

Montgomery S. Bradley

John S. Brown

Timothy V.A. Dillon

Ronald Field

Donna K. Grosvenor

Stephen Hosmer

Joan L. Jewett

Robert Mason

Isabel J}. McDonnell

Shirley J. McNair

Lavelle Merritt

Ruth N. Nelson

John B. Oliver

Mary Poole

Nancy Porter

Gerald G. Wagner

Rosa M. Walker

Richardson White, Jr.

Executive Director

Warren J. Iliff

Editor: Austin Hughes

Design and Production by Tom Jones

Photographs by Tom Jones

Black Swan Cygnets

Zoo News — Mammals

Zoo News — Birds

Zoo Map

Zoo News — Reptiles and Amphibians

Deer

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the

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Zoo, c/o National Zoological Park, Washington,

D.C. 20009. second-class mailing permit

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On February 19th, three black swans (Cygnus

atratus) were hatched in one of the National

Zoo’s lower waterfowl enclosures (number 30d

on map). The cygnets — as the hatchlings of

swans are called — had light brownish gray

downy plumage and black bills in contrast to

the black plumage and red bills of the adults.

Exhausted by the effort of hatching, the

cygnets spent the first day of their lives asleep

beneath their mother’s wings. At first each

cygnet’s downy feathers were encased in waxy

sheaths which protected them from the liquid

inside the egg, but these gradually rubbed off

through contact with the mother’s wings and

body. By the next morning, the three young

birds — “ugly ducklings’? by no means — could

be seen swimming with their parents and an

old female (their maternal grandmother) or

following the adult birds on land.

Over a month earlier, the adult swans had built

a large nest of sticks, and the female had lined it

with nest down which she pulled from the

underside of her own body. This down — which

is white in all swans, even the black swan —

appears under the contour feathers on the

underparts of a female in breeding condition.

Both parents shared in incubating the pale

green eggs. In this species the female — or pen,

as she is known in the terminology of the old

English swan-masters — usually is charged with

the task of incubation at night, while the male,

or cob, takes over for her during the day.

When one of the birds relieves its mate, there

is an elaborate changing-of-the-guard ceremony.

The relieving swan approaches the nest, holding

its head high, raising its wings, fluffing out its —

neck feathers, and giving a special two-syllable —

greeting call; the bird on the nest replies with

the same call. The new arrival climbs on the

back of the nest and remains there for a

minute or two, continuing to call and bow its

head. Then the bird on the nest stands up, .

allowing the other to slide under its tail onto

the eggs. When leaving the nest, the bird that

has been relieved picks up two or three beakfuls

of nesting material and passes them back to its

mate.

Two days before the eggs are ready to hatch, th

first sound is heard from them: this ts a |

repeated soft clicking, produced by the cygnet’s

breathing. Later the cygnet makes its first,

high-pitched vocalizations, to which the mother

replies by calling softly. The hatchling has a

so-called egg-tooth on the tip of the upper

mandible of its bill which it uses to break

through the eggshell; the egg-tooth falls off

shortly after the bird has hatched. The

hatchling makes a first opening near the end

of the egg, then rests for several hours. Next,

rotating inside the egg, it makes a complete

circle of similar holes all around the egg.

Finally it stretches its neck and legs energeti-

cally to push off the perforated end of the

egg with its head.

As shown in classic studies by Konrad Lorenz

and others, newly hatched waterfowl will accep

as their parent the first large moving object

they see. This phenomenon is known as

imprinting. Cygnets, ducklings, and goslings

hatched in incubators may become imprinted on

their human caretakers and follow them as them

would follow their parents. In the wild, |

however, because the young waterfowl is able

to swim and walk so early in life, a strong

instinct to follow its parents is very important

for its survival.

If it does become temporarily lost, the black

swan cygnet has a shrill distress call, which

induces one or both of its parents to indicate

their location by calling back or perhaps to

come and recover the lost cygnet. The young

bird may use this same distress call to

indicate that it is cold or hungry. Another call —

a gentle trill — is used to indicate that the

cygnet is sleepy. Members of the brood also

give these calls as they nestle together to sleep,

their eyes half closed and their bills often buried

in each other’s down. On these occasions,

their calls induce the mother to brood her

young or cover them with her wing as they

sleep and probably also encourage all of the

cygnets to go to sleep at the same time.

The black swan is native to Australia, where it

inhabits lakes, marshes, bays, and coastal

lagoons. About one hundred years ago it was

introduced to New Zealand, and now it Is

widespread there. Its highest concentrations are

found on the southeast corner of Australia and

on Tasmania. It is common along both the

western and eastern coasts of the continent and

well inland from them; in addition, occasional

wanderers have been found in suitable habitats

throughout the continent. The erratic

Australian rainfall often produces temporary

wetland, of which the swans soon take

advantage, sometimes remaining to breed. The

Dutch navigator Willem de Vlaming first

discovered this species on an estuary in

Western Australia later called Swan River; and

specimens he brought back to Europe excited

great curiosity and incredulity, since a

“black swan” had long been proverbial for

an impossible occurence.

Black swans are highly gregarious, often

assembling in large numbers; in 1957 for

instance, 50,000 were counted on Lake Albert

in South Australia. Unlike other swans they are

colonial nesters. Breeding mainly takes place

in December and January — late spring and

early summer in the Southern Hemisphere.

There is a great deal of variation, however; in

some years black swans in the wild breed all

year round — as the National Zoo’s black swans

do — and in some years very few of the

species nest at all. It has been suggested that

the timing of the breeding season in the wild

is related to the availability in luxuriant

quantities of the marsh plants and algae on

which the swans and their young feed.

At their vast breeding assemblages in the wild,

black swan pairs engage in a distinctive court-

ship ritual; this same behavior can be seen when

the Zoo’s black swans are mating. First both

birds repeatedly dip their heads beneath the

water, gradually synchronizing their movements,

and they pause occasionally to hold their heads

upright with their necks close together. Mean-

while the wings are held low, often dragging

in the water. Eventually the cob mounts, taking

hold of the pen’s neck feathers with his bill.

After mating, both swans rise half out of the

water, their necks extending straight up, and

nod their heads repeatedly. Then they swim

together in a circle, bathe and preen, and wag

their tails vigorously.

In the wild black swan cygnets normally stay

with their parents until they are six months old.

By this time they have increased in weight to

about seven pounds — over 25 times their

weight on hatching. Meanwhile their gray

downy plumage has been replaced by their

first coat of black contour feathers. At the age

of about 55 days — when the cygnet weighs

some two pounds — the feathers have appeared on

the shoulders and wings; tail feathers may

have started to grow slightly earlier but are not

readily visible. The Zoo’s current black swan

cygnets will reach this stage in late April. Next

to appear are the feathers on the belly, flanks,

and head and then the flight feathers on the

wing. Before these feathers appear in the Zoo’s

cygnets, the birds will already have been

pinioned. In other words, as is the practice

with all captive waterfowl kept in open ponds,

the part of the wing on which the primaries,

the major flight feathers, are located will have

been removed on one wing, rendering the

bird’s wing surface asymmetrical and thus

useless for flight. Down remains longest on the

back and underside of young black swans;

all other areas but these are feathered when

the cygnet is between 75 and 95 days old.

Zoo visitors will be able to see the current

cygnets going through these growth stages.

In addition, as black swans have done at the Zoo

for many years, the pair at the lower waterfowl

pond will probably mate and nest again this spring,

possibly laying a new clutch of eggs as soon as

early May.

A SOINEWS

Mammals

Red Kangaroo Joey

On February 25th, a movement was noticed tn

the pouch of the younger of the Zoo’s two red

kangaroo females (number 9i on map),

indicating that she had a joey. It was impossible

to say.exactly when the joey had been born;

but it would probably be several months

before the infant was regularly visible. However,

since the young of this species remain in the

pouch some 235 days, emerging occasionally

in the later months, visitors can expect to see

the joey in and out of the pouch throughout

the summer.

Reproduction in this species of kangaroo

(Macropus rufus) is better known than in most

marsupials; dramatic films of red kangaroo

births finally established the true nature of

kangaroo birth, which had been the subject of

learned controversy as long as these unique

animals had been known to science. It had

often been supposed that the infant — born

in an almost embryonic state and weighing

only about one thirtieth of an ounce or one

thirty-thousandth of its mother’s weight —

was assisted into the pouch in some way by the

mother. It was demonstrated, however, that

the young must climb into the pouch on its

own, hoisting itself through its mother’s fur

by means of its strong forearms. The mother

assists it only in that she makes the path from

the vagina to the pouch opening nearly

horizontal by sitting back in a slouching

posture with her tail tucked forward between

her legs.

The red kangaroo is named for a bright red

powder-like substance secreted from the skin

of the male’s chest and throat in breeding

season, which he rubs on his back with his

hands. This species is found on plains and in This female kangaroo is carrying an infant in her

near-desert areas throughout Australia. Recent Pouch (number 9/ on map).

investigations have shown interesting adapta-

tions in the red kangaroo’s reproductive life

for the harsh conditions under which it lives,

where infant mortality is very high.

only develops to the point where it comprises

It has been discovered that in the wild 60 to 70 about 100 cells. It remains at this stage of

percent of all red kangaroo females carrying development until the joey in the pouch

young in the pouch are pregnant with another — either dies or becomes independent; then the

offspring. It seems that females frequently second joey’s development continues, and it

copulate soon after giving birth, but the embryo is born about four weeks later.

New Bat Species

Two new species of bats have been placed on

exhibit in a cage to the right of the front door

between the branches of trees in forests. As

most other bats apparently do, it navigates by

of the Small Mammal House (number 15 on map) means of echo-location; in other words, it is

One, Linneaus’ short-tailed bat or the

common short-tailed bat (Corol/lia perspicillata),

is represented by two males and two females,

while the other, the somewhat larger Geoffroy’s

long-nosed bat (Anoura geoffroyi), is

represented by one male and one female. Both

species are native to Central and South

America and are members of the same family,

the American leaf-nosed bats (Phy/lostomidae),

so named for the fleshy ‘‘leaf’’ present on the

snouts of most of the species. They are quite

active and can readily be seen flying around

their unlighted enclosure with a swift, fluttering

flight.

Bats constitute the largest order of mammals

except for the rodents; there are some 2,000

species known. They are believed to have first

evolved the power of flight about 60 million

years ago in order to pursue winged insect

prey, and a majority of species are still

insectivorous. However, throughout the history

of the order, various species have adapted to

various other diets. The common short-tailed

bat is an example of a fruit-eating species as

are the large grey-headed fruit bats (Pteropus

poliocephalus) \ocated in the nocturnal room

at the Small Mammal House. Geoffroy’s

long-nosed bat also feeds to a certain extent

on the pulp of fruit; but it derives the bulk of

its nourishment from a still more unusual diet —

the nectar of flowers.

The common short-tailed bat is one of the most

abundant bats from Central Mexico to Peru

and southern Brazil. It feeds on a variety of

fruits, including ripe bananas, plantains,

mangoes, guavas, and wild figs, and it is

important for disseminating the seeds of a

number of fruit-bearing plants. At the Small

Mammal House, they appear to thrive on the

bananas hung at various locations around their

cage. Members of this species evidently have

a well-developed sense of smell, which they use

to locate their food in the wild; they are said

to forage twice a night, returning each time to

special roosting sites to eat and digest any

fruit they have found.

These bats spend their days in tunnels, mines,

caves, hollow trees, and buildings, often in

colonies numbering in the thousands. Other

species, including Geoffroy’s long-nosed bat,

may share the roosting site. The common short-

tailed bat is known for its rapid straight flight

in open areas, but it is also able to maneuver

with considerable agility when flying in

able to locate obstacles in its path by emitting

high-pitched vocal signals — inaudible to

humans — and gauging the distance of objects

from which they are reflected.

Geoffroy’s long-nosed bat shows remarkable

adaptations for its unusual diet. Its tongue has

bristles for lapping up nectar; and when

extended to its full length — as it is when the

bat reaches with it into the corolla of a flower —

it is longer than the bat’s head and body

together. It is believed that these bats play a

valuable role in cross-pollinating some of the

night-blooming plants on the nectar of which

they feed, in a manner analogous to the way in

which bees and other insects cross-pollinate

other flowering plants. Evidently pollen

rubbed off on the bat’s head and shoulders as

it feeds from a flower is frequently carried by

the bat to another flower of the same species.

Paca Born

A pair of pacas (Cuniculus paca) in a cage at

the rear of the Small Mammal House (number

15 on map)gave birth to a single young in early

February. The infant of these large rodents was

first spotted by keepers on February 5th, when

it was about three days old. It was very

precocious and already moving around quite

freely at that time; a day later it was seen

eating solid food. By the time it was a month

old, it was always the first to emerge from the

pacas’ nest box at feeding time.

The young paca’s precocious development is

rather unusual for a rodent. Mice and rats

(family Muridae), for instance, give birth to

10 to 15 blind and hairless young in a litter,

while the paca gives birth to one or occasionally

two well-developed offspring. However, the

young paca has a protracted adolescence and

stays with his mother up to five or six months,

much longer than most young rats or mice do.

These Central and South American rodents,

which as adults may weigh over 20 pounds,

are nocturnal forest-dwellers. They spend the

day in burrows which they dig themselves in

banks, among tree roots, or under rocks. The

burrow usually has several escape exits. Pacas

prefer areas where water is available nearby;

they are excellent swimmers, and readily take

to water to escape from predators.

The young paca born in February at the Small

Mammal House (number 75 on map).

Sugar Glider Births

Two of the females in the sugar glider group on

exhibit in the nocturnal room at the Small

Mammal House (number 15 on map) have

given birth to single young. Like other

marsupials, sugar gliders give birth to their

young in an extremely undeveloped condition

and nurse them in a pouch; thus the young

were not noticed until February 24th, when

they were both in the pouch and were both

estimated to be between a month and two

months old.

The sugar glider (Petaurus breviceps) is a

classic example of what is known as parallel

evolution. It has evolved parachute-like

membranes between its front and hind limbs

and gliding habits that closely parallel those of

the ‘flying squirrels’; flying squirrels, however,

are rodents, not marsupials, and are thus not

closely related to the sugar glider. Sugar gliders

have been reported to glide from tree to tree

for distances up to 50 yards. Like our familiar

North American flying squirrels, they are

strictly nocturnal; and another characteristic of

the sugar glider that parallels the flying squirrel

is its large eyes, adapted for improved night

vision.

During the day, sugar gliders sleep in nests in

hollow trees. For this reason, although they are

among the most common of Australian

mammals, they are not often seen. They line

their nests with leaves, which they usually

collect by hanging from their hind feet, picking

the leaves with their forefeet, and in turn

passing them to the tail, which coils around

them and holds them while the sugar glider

returns to its nest. While the animal is gliding,

the tail functions as a rudder, so when carrying

nesting materials the sugar glider cannot glide

but must climb back along the branches.

The name ‘‘sugar glider’ derives from the fact

that in captivity members of this species have

proved to be very fond of sugar. In the wild,

their “sweet tooth”’ is satisfied by feeding on

blossoms. In addition, they eat insects and

fruits.

Like all marsupials, the sugar glider has a

very short gestation period; it is only three

weeks between conception and birth in this

species. The young are fully independent of

the mother by the time they are about four

months old, but they may remain in their

parents’ nest for several years. Groups made up

of parents and their offspring of previous

years may number up to a dozen, all sharing

one nest with the same tolerance for one

another’s close proximity that can be seen in

the Zoo’s sugar glider group.

Renovations Scheduled

The planned renovation of the National

Zoological Park is scheduled to begin this fall.

At that time two of the Zoo’s older buildings,

the Monkey House (number 27 on map) and

the Puma House or Lesser Cat Building

(number 29 on map), will be closed for

complete remodelling. The animals in these

buildings will either be kept in other parts of

the Zoo or sent to other zoos, either on loan

or permanently.

Several months later, the Lion House (number

23 on map) will be closed. This building will

be replaced by spacious grottos covering the

entire current Lion House hill, to be occupied

by all of the greater cats. Before the building’s

closing, however, the complex process of

relocating all of its inhabitants will begin. The

sloths and tree kangaroos will find temporary

homes in the Reptile House (number 79 on

map). Other animals will be sent to other

zoos, some temporarily, some permanently.

The Zoo’s famous white tigers will be loaned

to Chicago’s Brookfield Zoo, the home of the

male tiger currently on loan to the National

Zoo. This male has incidentally bred with both

the normally colored female Kesari and the

white female Mohini.

Rendering—Drawing by architects Faulkner,

Fryer, and Vanderpool of the new Monkey House;

there will be larger cages and a smaller number

of species on exhibit.

PECTIVE > MONKEY HOUSE - EXTERIOR

FAULKNER, FQYER AND VANOERPOOL © ARCHITECTS FEeQuaRy q ANTS.

The construction in the Lion House area will

also necessitate the evacuation of the

enclosures behind the building (numbers 22a-0

on map). One of the results will be that the

young pair of tapirs now located there

(number 22e on map) will have to be moved to ©

the Zoo’s other tapir enclosure (number 26e

on map). The older pair that formerly occupied

this enclosure have been sent — along with

their recent offspring — to the Salisbury,

Maryland, Zoo.

Other current construction includes the

preparation of enlarged outdoor yards for the

giant pandas (numbers 10 a-b on map); work

is scheduled to be completed by labor day.

Each of the new yards will cover a quarter of

an acre — four or five times the size of the

pandas’ present yards — and will be planted

with willow trees and bamboo. A moongate

will connect the two enclosures. It will be

covered with wire mesh through which the

pandas will be able to see each other, and it

will be opened for mating when the pair are

sexually mature in 1975 or 1976.

TOF cs ee Oy ty ae tag ' PN

CAGES: MATIGNAL 7OCe

Coscoroba swans, located on the waterfowl pond

behind the Bird House (number 5 on map),

Coscoroba Swans

One of the most interesting of recent waterfowl and southern Brazil through Tierra del Fuego.

acquisitions is a pair of Coscoroba swans

(Coscoroba coscoroba), currently on exhibit in

an enclosure behind the Bird House (number 5

on map). These handsome white birds with

pink bills and legs may at first sight appear

to resemble very large geese rather than

swans. Their necks are proportionately

shorter than those of typical swans (genus

Cygnus); and their legs are not set so far back

on the body as in familiar swan species,

resulting in far less awkwardness on land.

Indeed, many authorities question whether

Coscoroba coscoroba should properly be called

a swan at all; as can be seen from a comparison

of its broad, flattened bill with a goose’s

narrow bill, however, the differences between

it and true geese (Anser and Branta) are even

greater. It is currently considered to be

intermediate between the true swans and a

group of rather primitive waterfowl known as

the whistling ducks or tree ducks (genus

Dendrocygna).

Coscoroba swans are found in the southern

third of South America from northern Chile

They are believed to feed mainly on water

weeds, seeds, and some aquatic invertebrates.

They usually build their nests in shallow

water, piling up a small island of reeds and mud

and lining a hollow in its center with grass

and down. The young do not resemble those

of true swans; for, rather than being wholly

gray, they have a band of pure white across the

back of the head and black markings on the

top of the head, on the face, and on the back.

Among other recent acquisitions (number 30d

on map) are a male and two females of another

are a male and two females of another

interesting waterfowl species, the falcated duck

(Anas falcata). These relatives of the mallard

breed in eastern Siberia and winter in China,

Korea, and Japan. The species is distinguished

by the long, curving nuptial plumes that adorn

the drake’s shoulders. These silvery feathers

appear only in the spring and summer breeding

season; the Zoo’s male is wearing them at

this writing.

A hoopoe in the indoor flight room at the

Bird House (number 5 on map).

Hoopoes Nest

Boat-Billed Heron Chicks

Spring was heralded by increased activity among On March 8, three boat-billed herons

many of the avian species in the Indoor Flight

Room at the Bird House (number 5 on map).

Among the most noticeable were the six

hoopoes (Upupa epops) in the room. Males of

this species fought with each other, sometimes

taking hold of each other’s bills in mid-air, and,

chattering noisily, repeatedly pursued other

males and females around the room. At least

three males divided up the room, each choosing

a perch from which he gave the unforgettable

“hoop-hoop”’ call for which this species is

named. On one occasion a male was seen

courtship-feeding a female, flying up to her to

present her with a large cricket he had found.

Finally at least one pair began to nest and laid

two eggs in one of the nest-boxes set in the

artificial cliffs of the room. Often the male

could be seen flying up to the nest entrance

to feed his mate, who spent most of her time

inside the nest incubating the eggs. When the

young hatched in late March, they were fed by

both parents. They would not emerge from the

nest until a month old, when they would be

little different from the adults in plumage but

with much shorter bills. |

(Cochlearis cochlearis) were hatched in a

large, disorderly stick nest in the spacious

marsh bird cage at the rear of the Bird House

(number 5 on map). The young herons had

gray down on their bodies and black heads.

Their bills were short and relatively narrow, in

contrast to the remarkably developed bills of

the adults.

No one knows for certain what type of diet the

boat-billed heron has evolved its unique bill to

feed on. This species is nocturnal in the wild

and inhabits dense mangrove swamps from

southern Mexico south through Brazil, where

it is seldom seen. Some have reported that it

feeds on a typical heron diet of worms,

crustaceans, amphibians, and fish; but others

have doubted whether its unwieldy bill could

be used to capture such active prey as frogs

and fish and have expressed the opinion that

ijt must be used to strain through mud for

slower-moving lower animals. One use of the

bill is known; in courtship, both males and

females clatter their bills and erect their long

black crests:

A 3 OMAP

. Connecticut Avenue pedestrian entrance

. Connecticut Avenue vehicular entrance

Deer and antelope areas (a-})

. Great Flight Cage

Bird House

. Pheasant and crane line (a-r)

. Raptor cages (a-d)

. Delicate-hoofed stock building (a-c)

. Hardy-hoofed stock complex (a-1)

. Panda House (a-c)

COMNOTAWN =

esas

. Elephant House

. Water birds (a-e)

. Hawks and owls (a-c)

. Goat mountain areas (a-e)

. Small Mammal Building

. Lesser Pandas

. Prarie dogs

. Bears and monkeys (a-m)

. Reptile House

. Tortoise yard

. Monkey House

. Hardy Animals (a-o)

. Lion House

. Komodo Dragon

. Bears (a-})

. Water animals (a-e)

j 13c

13a |

. Sea Lion pool

. Wolves, foxes, and wild dogs (a-l)

{Messer Cats

. Waterfowl ponds (a-d)

. Police Station—Restrooms—First Aid

. Restaurant

. Picnic Area

. Window Shop

. Souvenir Kiosk

. Rock Creek Parkway entrance

. Friends of the National Zoo Offices

. FONZ Education, Editorial, and Tour

Guide Offices

nm Telephone

6 ? Restrooms

K- Trackless Train Stops

we Parking

———-—» Walking Tour Route

(From the Trackless Train

Stations)

eo Ce,

A OMAP

oma

SOMNOOAWN =

Connecticut Avenue pedestrian entrance

Connecticut Avenue vehicular entrance

Deer and antelope areas (a-j)

Great Flight Cage

Bird House

Pheasant and crane line (a-r)

Raptor cages (a-d)

Delicate-hoofed stock building (a-c)

Hardy-hoofed stock complex (a-i)

Panda House (a-c)

. Elephant House

. Water birds (a-e)

. Hawks and owls (a-c)

. Goat mountain areas (a-e)

. Small Mammal Building

. Lesser Pandas

. Prarie dogs

. Bears and monkeys (a-m)

. Reptile House

. lortoise yard

. Monkey House

. Hardy Animals (a-o)

. Lion House

. Komodo Dragon

. Bears (a-j)

. Water animals (a-e)

. 9€a Lion pool

. Wolves, foxes, and wild dogs (a-l)

. Lesser Cats |

. Waterfowl ponds (a-d)

. Police Station—Restrooms—First Aid

. Restaurant

. Picnic Area ~

. Window Shop

. Souvenir Kiosk

. Rock Creek Parkway entrance

. Friends of the National Zoo Offices

. FONZ Education, Editorial, and Tour

Guide Offices

é9

¥-

eee

Telephone

Restrooms

Trackless Train Stops

Parking

———-—- Walking Tour Route

22k

22!

(From the Trackless Train

Stations)

22)

Reptiles and

Amphibians

The male of the Zoo’s pair of Chinese alligators,

at the Reptile House (number 19 on map).

Chinese Alligators

The National Zoo’s pair of Chinese alligators

(Alligator sinensis) are among the oldest

animals in the collection, having arrived here

in 1937; but recently they have shown signs

of new liveliness. This past winter, the pair

were moved to new quarters — a spacious

enclosure on the right hand wall of the

Reptile House (number 19 on map) similar to

those occupied by the Zoo’s other full-grown

crocodilians — and they soon began behaving

in a way that raised hopes of an almost

unprecedented breeding of this rare species in

captivity. They were observed mating in

December, and thereafter several signs seemed

to indicate that the mating may have been

successful. The female’s abdomen appeared

swollen, indicating the possibility that she was

carrying eggs. Moreover, she began roaring —

carrying eggs. Moreover, although she is

considerably smaller than the male, she became

aggressive towards him and kept him away from

her vicinity. She also stopped eating — again

normal for a female prior to laying her eggs.

While it is too early to tell as yet, keepers

continue to watch the female Chinese

alligator closely for further signs of impending

nest-building and egg-laying.

The Chinese alligator is found only in the flood

plains of the lower Yangtze valley, although its

distribution is presumed to have been much

wider in the past. It is a rare species and is

seldom exhibited in captivity. Almost nothing

is known of its habits in the wild.

Rat Snake Exhibit

Rat snakes are among the most beautifully

colored of North American reptiles. A new

exhibit at the Reptile House (number 19 on

map) shows some of the many differently

colored forms of this species that are found in

the United States. This exhibit contains three

races of rat snakes — Elaphe obselata obselata,

Elaphe obselata quadrivittata, and Elaphe

obsoleta lindhiermeri. These are colored,

respectively, black, yellow, and blotched gray.

This species has often been called the most

arboreal of our snakes. Certainly they do spend

a large amount of time in trees, seeking such

prey as birds, tree frogs, and squirrels. The

name “‘rat snake’ derives from the other

large constituent of their diet — small rodents

such as rats and mice.

A yellow rat snake.

Deer, known to scientists as the family Cervidae,

are found throughout four continents — Asia,

Europe, North America, and South America —

and also appear in the northwest corner of

Africa. In addition, they have been widely

introduced by man on Australia, New Zealand,

and several oceanic islands. Though they range

in size from a twenty-pound full-grown South

American pudu to an 1,800-pound bull moose,

most of the forty living species in this family

are unmistakable as deer; the antlers carried

by the males of most species are alone sufficient

to distinguish them from any other mammals.

The National Zoo has an extensive collection

of members of this family, consisting of 48

individuals of seven species. There are sizable

breeding herds of muntjac (Muntiacus muntjak ),

sika deer (Cervus nippon), Eld’s deer (Cervus

eldi), Pere David’s deer (E/aphurus davidianus),

and reindeer (Rangifer tarandus). There are

also three axis deer (Axis axis) and one

white-tailed deer (Odocoileus virginianus).

Muntjac are tiny and quite primitive deer;

adults are less than two feet high at the shoulder

and weigh between about 35 and 75 pounds.

Native to the forests of India, China, and

Southeast Asia, they are represented at the

National Zoo by a group consisting of one adult

male, two breeding females, three young males,

and three young females (number 3c on map).

Six of these animals were born at the Zoo.

Of the more typical deer, the sika deer of Japan,

Formosa, and eastern China has been

represented in the National Zoo’s collection

since 1905; 197 of this species have been born

here since that time. The current herd consists

of one adult male, two adult females, and one

yearling of each sex. In addition there are two

juvenile males — already bearing short antlers

sharing a mixed exhibit (number 3j on map)

with two African pygmy goats (Capra hircus),

a pronghorn (Antilocapra americana), and the

Zoo’s single male white-tailed deer and three

axis deer. A close relative of the sika deer, the

Southeast Asian Eld’s deer or brow-antlered

deer, is represented by two adult males, three

Even more precarious is the survival of Pére

-David’s deer; this species, which fossils show was

native to northeastern China, has not existed in

the wild for hundreds of years. It was preserved

only in an Imperial Game Park in Peking; and,

when it was exterminated there during the

Boxer Rebellion, it was saved only by carefully

organized breeding of the few individuals that

had found their way to European zoos. Since

1968, births in the National Zoo’s herd

(number 3h on map) have contributed eleven

individuals to the worldwide total of approxi-

mately 450 Pére David’s deer.

The final species in the Zoo’s deer collection,

the reindeer, is distributed in northern wood-

lands and tundras around the globe. Twenty

subspecies have been named; those native to

North America are usually known as caribou.

The Zoo’s population (number 3d-e on map)

includes individuals of the barren-ground

caribou (Rangifer tarandus arcticus) and of the

Siberian reindeer (Rangifer tarandus sibiricus ),

as well as one cross between these two sub-

species and two individuals of unknown race.

Deer are grouped in the order Artiodactyla or

even-toed hoofed mammals. Like other members

of this order, they support their weight on two

hoofed toes, which are descended from the

third and fourth of the original five toes that

the ancestors of all mammals had. The first

digit has been lost, while the second and fifth

are vestigial; they form the so-called ‘‘dew-

claws’’ or pseudo-claws at the side of a deer’s

foot, which never touch the ground except

when it is very soft. Deer are included ina

suborder of the Artiodactyla known as the

ruminants, distinguished by the remarkably

complex digestive system they have evolved.

Like other members of this suborder — which

also includes giraffes, pronghorns, antelope,

cattle, sheep, and goats — deer lack incisors on

the upper jaw. In their place, there is a pad of

tough flesh against which the lower incisors

press to tear off grasses, leaves, or other plant

food. As soon as it is broken off in this way,

the food is swallowed without being chewed.

adult females, one female yearling, and one male Ruminants have a four-chambered stomach,

fawn born this past January (number 3i on map),and each mouthful as it is swallowed passes

There are three races of Eld’s deer; the Zoo’s

herd belong to the Burmese race (Cervus eldi

thamin), also known as the thamin. The other

two races have been considered in danger of

extinction for some time; now experts fear that

the thamin too is in danger of succumbing to

uncontrolled hunting and the conversion of

its habitat for agriculture and the grazing of

domestic animals.

to the first of these chambers, a large storage

pouch known as the rumen. When the animal

is finished with its grazing or browsing, it

withdraws to a safe place and, by contracting

the rumen, brings a portion of the food it

has gathered back up into its mouth. Then

mouthful by mouthful it carefully chews

this stored food — or “‘cud,”’ as it is usually

called — with its molars and premolars;

when swallowed again, the fully masticated

Eld’s deer on brow-

antlered deer (number

3i on map).

cud bypasses the rumen and is digested by the

rest of the stomach. This system of digestion

is of obvious value in protecting the ruminant

from predators, since the animal is able to

gather and store a large quantity of food in

a relatively short time and then retire to chew

and digest at leisure in a protected place.

Another advantage derives from the presence

of bacteria living symbiotically in the rumen.

These bacteria break down the cellulose in

the walls of plant cells — which the ruminant

alone lacks the necessary enzymes to digest —

and thus liberate the more nutritious cell

contents.

Deer use this remarkable digestive apparatus to

feed on a considerable variety of kinds of

vegetable matter. Most are both grazers and

browsers; in other words, they eat both grasses

and the leaves and shoots of trees and shrubs,

though the percentage of each of these types of

food may vary from species to species and

from season to season. Some species include

more exotic elements in their diets. The

reindeer of the arctic tundra, for instance,

consume large amounts of lichens and mosses.

The adaptability of deers’ feeding habits is

shown by the ease with which most species

adapt to a new diet in captivity. All of the Zoo’s

deer thrive on alfalfa hay and a commercial

food for horses in pellet form. Some species

are also given a specially formulated vitamin-

B- and selenium-supplemented ‘“‘sweet feed”’

at certain times of the year; and all are able

to graze on the grass growing in their enclosures,

which is replanted periodically, and are

occasionally given freshly cut boughs to browse

on.

Antlers are, of course, the most obviously

unique characteristic of deer. It is true that

various other hoofed mammals have also

evolved head weapons and adornments;

antelope and their relatives have horns with

bony cores, rhinoceroses have boneless horns

that grow from the hide, and giraffes and okapis

These ancestral deer were quite small compared

to the most familiar recent species. As do such

primitive present-day species as the muntjac,

they had elongated canines on their upper jaws;

but they had no antlers — not even such very

simple antlers as those worn by the male

muntjac. Among modern species, the Chinese

water deer (Hydropotes inermis) and the musk

deer (Moschus moschiferus) are also antlerless

but have elongated upper canines.

The male muntjac’s antlers are straight, short

spikes, adorned only by one tiny hooklike

- branch near the base of each antler. Other

species at the Zoo illustrate some of the

variety of shapes of multi-branched antlers that

occur in other members of the family. The

sika deer’s antlers represent one of the most

familiar types; other members of this genus

such as our familiar American elk or wapiti

grow antlers with essentially similar structure.

In these species, the antler is based on a main,

rear beam, which may have a number of

forward-directed points or tines growing from

it; and a large forward-directed branch known

as the brow-tine grows from the base of this

beam. Stags grow an increasing number of

points as their age increases, although it is

incorrect to suppose that they add a new point

each year. When the stag becomes old, however,

the antlers tend to degenerate and have fewer

points than those of a stag in his prime. In the

sika deer, the maximum number of points per

antler is usually four including the brow-tine,

although stags with five or even six points per

antler occasionally occur. At this writing, the

Zoo’s full-grown male sika deer is carrying

antlers with three points each. The Eld’s deer

belongs to the same genus as the sika deer and

wapiti, but its antlers differ in one notable

particular. The brow-tine is elongated and

forms one continuous curve with the rear

beam of the antler; this is the source of the

alternative common name of this species,

brow-antlered deer.

have permanent skin-covered bony proturbances

on their heads. But all of these structures are

permanent, while the antlers of deer are grown

and shed each year. The anomalous pronghorn —

neither deer nor antelope — annually grows and

sheds pronged sheaths of horn that surmount

paired permanent bony plugs on its head. The

antlers of deer, however, have no horn in their

make-up but consist simply of bare bone.

Interestingly, the earliest deer we know of had

no antlers. The deer family seems to have made

its first appearance approximately 40 million

years ago in Asia; and by the Miocene period —

from 25 to 10 million years ago — deer had

spread throughout Europe and North America.

Other genera represented at the Zoo have some

still more unusual forms of antlers. The reindeer

is the only species of deer in which the females

regularly grow antlers, although very rarely

females of some other species are found with

diminutive antlers. There is a forward beam and

a rear beam on each antler in both males and

females, and there are points on both beams.

The number of points is much greater in males

than in females, and the male’s antlers are

considerably larger. One male of the barren-

ground caribou had 52 points on a pair of

antlers. Pére David’s deer also has unique

antlers. A front beam grows almost straight

up from the forehead, and the other branches

grow backwards from this.

The growth of antlers is a phenomenal process,

the exact nature of which is as yet not

entirely understood. First, the young male

develops a pair of skin-covered protuberances

from the frontal bone of the skull known as

pedicels or pedicles; these will be the bases on

which each year’s set of antlers will grow.

Experiments have shown that if the pedicles

are removed, antlers are never developed; and

there is some evidence that the formative

tissue of antler originates in the connective

tissue of the skin that covers the pedicles. In

any event, the antler begins as fibrous tissue

below the pedicle skin. More and more of this

fibrous tissue develops; and, as it continues to

grow, it is gradually turned to bone at its

base. Bone-forming calcium is carried from

the cavity of the skull to the growing antler

by means of an elaborate system of blood

vessels. Meanwhile, the blood-rich pedicle

skin grows too and provides a covering —

called “velvet’’ — for the developing antler.

When the antler has reached its full size and is

fully ossified, the bone at its base becomes

increasingly dense, forming a ring known as

the coronet or burr just above the pedicle

which eventually cuts off the blood supply

from the cavity of the skull to the antlers.

Subsequently the velvet too loses its blood

supply and dies. The dry velvet begins to

peel off, a process which the stag frequently

helps to accelerate by rubbing his antlers on

shrubbery. When the velvet is shed, the stag

is said to be “in hard antler.”

In temperate climates, stags of most species

are in velvet during the spring and summer

and by the fall mating season or ‘“‘rut’’ are in

hard antler. The sika deer of Japan, for

instance, have finished shedding the velvet

Male reindeer in velvet

(number 3a-b on map).

about mid-September, and the rutting season

lasts from that time till the end of October.

Stags of most Temperate Zone species

retain their antlers throughout the winter

and drop them in the spring, the next year’s

growth beginning shortly after the previous

year’s antlers are dropped. In the sika deer,

most males drop their antlers in May in the

northern hemisphere, although older

individuals may do so in April and younger

ones in June.

As this sort of schedule suggests, antler growth

and the male’s annual reproductive cycle are

closely connected. Experiments have shown,

for instance, that the male hormone testos-

terone plays an important role in stimulating

antler production. Male deer castrated as

fawns will not ordinarily grow antlers;

however, if such a castrated male — ora

spayed female — is given testosterone injec-

tions, it will grow small antlers. Moreover,

in Temperate Zone species the growth of

antlers closely parallels cyclic changes in the

testes. The testes are small and inactive in

spring when the previous year’s antlers are

being dropped and new antlers are beginning

to grow. As the development of the antlers

proceeds, the testes enlarge, and sperm

production increases, reaching a peak that

coincides with the period of hard antler and

the mating season.

The mechanism responsible for the annual

growth and shedding of deer antlers is only

beginning to be understood; but recent

investigations have shown that photoperiod

— the amount of light to which the animal

is exposed each 24 hours — plays a crucial

role. In one study, sika deer stags were kept

under artificial light so that the effects of

different ‘‘day lengths’’ on their antler

production could be ascertained. It was found

that new antler growth was usually stimulated

by a period of days containing gradually

increasing amounts of light per 24 hours that

took place subsequent to a period of gradually

decreasing amounts of light per 24 hours.

This corresponds, of course, to the natural

beginning of new antler growth as days begin

to lengthen in the spring following the

decrease in day length the previous fall.

However, the length of the artificially con-

trolled “‘year’’ could vary greatly. Sika deer

stags could be made to grow as many as four

sets of somewhat stunted antlers in one

calendar year if subjected to four artificially

produced three-month cycles of decreasing

and increasing day lengths during that time.

Pére David’s deer stag

(number 3h on map).

Female reindeer (number 3a-b on map), This is

the only species of deer in which females

regularly bear antlers.

Stags also tended to produce only one set of

normally sized antlers over a two-year period

if subjected to a cycle of day lengths twice

as slow as the natural one.

Further study, however, showed that there Is

no simple cause-and-effect relationship between

photoperiod and antler growth. When sika

deer were exposed to ‘‘days”’ of constant length

for a prolonged period of time, they adjusted their

antler growth in interesting ways. When exposed

constantly to exactly equal ‘‘days’’ and

“nights,”’ stags failed to shed their antlers at

all. When exposed to unvarying eight-hour,

sixteen-hour, or 24-hour ‘‘days,”’ however,

they developed an antler cycle equal in

length to about 85 percent of the solar year.

This and other evidence seems to indicate

that there is a built-in rhythm on which

antler-growth is based and that this rhythm

is stimulated and modified to a certain

extent by photoperiod. Interestingly, such

tropical species as the eld’s deer shed their

antlers each year, but each stag has a cycle

of his own which he does not necessarily

share with any other stag. In addition, stags

of this species are able to breed throughout

the year. Male muntjac, too, produce motile

sperm throughout the year; and on Java,

some males of this species can be seen in

velvet in the-spring and some in the fall.

In the sika deer and other Temperate Zone

deer, the antlers’ most apparent function is

in the intensive combats that take place

among males at the onset of the rut. Another

preparation for these combats can be seen in

the dramatic thickening of the musculature

of the neck that takes place after the velvet

begins to shed. Evidently this increased

development of the neck is helpful in

supporting the weight of the antlers and in

antler-fencing, and in a stag in his prime it

The Zoo’s sika deer herd (number 3g on map).

must also have a decided psychological

effect. These fights are essentially tests of

strength and endurance; since a stag is able

to lock antlers with an attacking opponent,

serious injury to either combatant is relatively

rare. As the rut progresses, each mature stag

gathers a herd or harem of hinds to breed

with; and he will continue to threaten or

fight any other stag that approaches his herd

too closely.

The annual production of antlers — which in

some species may weigh as much as a quarter

of the animal’s permanent skeleton — obviously

must put a severe strain on the stag’s system;

and it is felt that such a biologically taxing

process must have had some very important

function to have been of selective value. But

several scientists have questioned whether

their function in inter-male combats is

sufficient to account for the evolution of

such elaborate structures. In the red deer

(Cervus elaphus) about one percent of males

are antlerless; and yet these so-called

hummel stags appear to be no less able to

obtain and breed successfully with herds of

females than are antlered stags. Male muntjac,

it has also been pointed out, have evolved

antlers but use mainly their elongated canines

in their combats.

There is some evidence, however, that a major

function of antlers, at least in some species,

is to be found not in their use as weapons but

in the psychological effect they have on other

deer of the same species. The growth of antlers

is only one of several changes in the appearance —

of males that accompany the rut in non-tropical

species. The thickening of the neck muscles is

another, and there are also changes in the pelage

that take place at the same time. For instance,

stags of the sika deer and other species develop

heavy neck manes in the fall. In autumn, rein-

deer grow longer white hairs in among the

brown summer hair, producing a striking gray

color which is particularly impressive on the

neck. All these changes in the region of the

head and neck — which is the area first seen by

another of the same species — cannot fail to»

have an effect.

Other evidence from the reindeer provides —

further suggestions of the value antlers can

have as social signals. For example, the antler

combats that take place between male

reindeer at the time of rut have been reported

to take place only between males of approxi-

mately equal age and, therefore, approximately

equally sized antlers. Older males come into

rut earlier than younger males, so that older

males begin to gather herds of females before

younger males. At this time, younger males

will defer automatically to an older male and

avoid conflict with him. When the younger

males come into rut and begin to show

aggression towards other males, they tend to

fight with males of about their own age which

are also just coming into rut at the same time.

The size of the antlers quite possibly help

such males in recognizing each other.

When a male sees a male of similar age

approaching he may avoid fighting but warn

the other male away by means of various

threatening signals. This is particularly likely

to happen after harems have been formed.

One such signal involves the antlers, which

the male reindeer rubs on a nearby shrub or

tree as a warning. Stags of many other

species of deer rub their antlers on branches,

often stripping them of leaves, apparently as

a kind of warning mark. :

The reindeer is aberrant, of course, in that

the females bear antlers; and the female

reindeer’s antlers seem even more clearly to

play arole as social signals. Interestingly, the

adult female’s antler-growth cycle does not

correspond with that of the adult male. In

Scandinavia, male reindeer shed the velvet

during August and are in hard antler for a

rut that lasts from late August to late October.

In early winter, the males begin to drop their

antlers, although all do not do so at once. In

this respect, they differ from such typical

deer as the sika in that they are antlerless in

winter. Breeding female reindeer, on the other

hand, do keep their antlers until spring; they

shed them at calving time in April and soon

afterwards begin to grow a new set. In

winter reindeer live in mixed herds of males

_and females. In these herds, the dominance of

females increases greatly with respect to the

then mainly antlerless males, and evidently

_ the possession of antlers plays a large role in

enhancing the females’ status.

In the far northern winter, the life of the

reindeer is very difficult, and usually the

lichen, brush, and grass on which they feed

can only be found by digging through the

snow. With their front legs the reindeer dig

feeding craters in the snow about sixteen

inches wide, and usually certain animals

regularly defer to others for first access to

the craters. Calves born the previous spring

follow their mothers and depend on them to

find food; and thus the females’ relatively

high social status at this time has direct value

for the survival of their offspring and, thus,

for the perpetuation of the species.

The barren-ground caribou of the Canadian

north make large-scale annual migrations to

traditional calving grounds in the north every

spring; pregnant females initiate these mass

movements, travelling in herds that number in

the thousands, while males follow several

days behind them. When they reach the

calving grounds, as many as 80 percent of all

the year’s births may take place during a four

or five day period. Other non-tropical deer

also regularly give birth in the spring when

conditions are optimum for the fawns’

survival. Tropical species — in keeping with

their lack of a definite mating season — may

give birth at any time during the year,

although there may be a birth peak of several

months when vegetation is at its most

luxuriant. On the Indonesian island of

Lombok, for instance, where there are well-

marked wet and dry seasons, most muntjac

births take place during the rainy season.

At the National Zoo, too, the tropical species

— the muntjac and Eld’s deer — give birth

throughout the year. Young of the former

species were born this past November and

January, and one fawn of the latter species

was also born in January, 1973. But for the

rest of the Zoo’s deer, spring and early

summer are the regular time for birth as they

are for non-tropical deer in the wild. At this

time in 1972, a sika deer, two reindeer, and

five Pére David’s deer were born; and Zoo

visitors should be able to expect a similar

number of fawns this year.

Back cover: Sika deer stag (number 3g on map),