Polar Bear Husbandry at the Moscow Zoo

I. V. Yegorov, Y. S. Davydov, Moscow Zoo, Russia

History of Polar Bears at the Moscow Zoo

The first information on the breeding of Polar Bears at the Moscow Zoo refers to 1940. In December of that year, the Polar Bears at the Moscow Zoo had a male cub, which was successfully raised by the female.

In 1945 a group was formed that consisted of a male and two females, but they did not produce any offspring. In 1949 the male was replaced, and in March 1950 the first mating was observed. From 1950 through 1952 this group produced three litters, of which two had one cub each and one had three cubs.

The following information on the Polar Bears at the Moscow Zoo refers to 1967, when a new group was formed, which consisted of two males and two females (Table 1).

Table 1. The composition of the Polar Bear group formed in 1967.

Sex	Name	Year of birth	Origin	Arrival at the Moscow Zoo
Male	Lel’	1964		10.11.65
Male	Sever	1965		16.09.67
Female	Snegurka	1965		10.11.65
Female	Zvyozdochka	1957	Wrangel Island	1959

This group existed until 1983 and bred regularly (Table 2).

Table 2. Breeding of the Polar Bears at the Moscow Zoo from 1970 through 1983 (since both males participated in the mating, the sire is not known)

Female	Date of mating	Date of birth Number of cubs	Notes
Snegurka		15.11.70 0/2	0/1 stillborn, weight 0.6 kg
Snegurka		18.11.71 0/0/1	At the age of 4.5 months (09.04.72) transferred to the cubs’ enclosure
Snegurka		17.10.73	Miscarriage
Snegurka		21.10.74 1/1	Died at the age of three days (24.10.74) Death weights: 0/1 – 0.54 kg and 1/0 – 0.64 kg
Zvyozdochka		23.11.74 1/0	At the age of 4 months (20.03.75), with the weight of 18.0 kg, transferred to the cubs’ enclosure
Snegurka		25.11. 75 1/1	Eyes opened on the 40th day. At the age of 5 months (30.04.76), with the weight of 18.4 kg, transferred to the cubs’ enclosure, female sent to Khar’kov
Zvyozdochka		29.11.76 1/1	At the age of 4 months (29.03. 77), with the combined weight of 36.2 kg, transferred to the cubs’ enclosure
Snegurka	March 12, 1977	05.12.77 2/0	Died of pneumonia at the age of six days (11.12.77). Death weights: 0.64 kg and 0.63 kg
Snegurka	From April 9, 1978	30. 09.78 0/1	At the age of 6 months (30.03.79), with the weight of 20.0 kg, transferred to the cubs’ enclosure
Zvyozdochka	April 2-8, 1978	08.11.78 0/2	At the age of 4.5 months (25.03.79), with the weights of 12.0 kg and 13.0 kg, transferred to the cubs’ enclosure
Snegurka		28.11.79. 0/1	Died at the age of three days (01.12.79)
Zvyozdochka		04.11.80 0/2	At the age of 4.5 months (20.03.81), with the weights of 10.0 kg and 10.75 kg, transferred to the cubs’ enclosure
Snegurka		02.12.80 0/1	At the age of 3.5 months (20.03.81), with the weight of 9.65 kg, transferred to the cubs’ enclosure
Snegurka	May 3-15, 1981	1.12.81 0/0/2	Killed by the female on 5.12.81
Zvyozdochka	From April 5, 1982	5.12.82 0/1	At the age of 4 months (4.04.83), with the weight of 17 kg, transferred to the cubs’ enclosure
Snegurka		9.12.83 1/0	Stillborn

This group ceased to exist in 1984 after both males died and the females were transferred to the Yerevan Zoo because of the beginning reconstruction of the enclosures of the “Polar World”.

The present group of Polar Bears was formed after the reconstruction of the enclosures was finished. Information on the composition of this group is presented in table 3.

Table 3. Breeding group of Polar Bears at the Moscow Zoo from 1995 to 2004.

Sex	Name and International Studbook #	Year of birth	Origin	Arrival at the Moscow Zoo
Female	Murma, 1202	1990	Barents Sea	18.05.95
Male	Wrangel, 1201	1990	Wrangel Island	18.05.95
Male	World, 0865	1991	Kazan Zoo	26.01.94 (died on 09.02.02)
Female	Simona, 1616	27.11.94	Leningrad Zoo	31.05.97
Male	Umka, 1618	1991	Taimyr peninsula	23.04.03

Husbandry conditions

The Polar Bears are housed in two enclosures of the so-called "Polar World". The enclosures have outside areas paved with cement and pools. The large outside enclosure is 9.5 to 11 meters wide and 42 meters long. It is shaped almost as a semi-circle, and there is a pool along the perimeter on the visitors’ side, which is 4.5 meters deep and 5 meters wide on the bottom and up to 9 meters wide at the top. The bears are separated from the visitors by 40 mm thick triplex glass, and the pool is filled with water. The stone back wall of the enclosures is up to 8 meters high. The second enclosure has an outside area that is 10 meters wide and 7 meters long, and it also has a pool on the visitors’ side that is 4.5 meters deep and 2.5 meters wide. There are steps going down into the pool, and the bears are separated from the visitors by triplex glass that is 2.5 meters high. The back walls of the enclosures have sliding doors through which the animals can get into their bedrooms. There are eight bedrooms (3.5 x 6 m; 3.5 x 4.5 m; 3.0 x 4.0 m and five bedrooms measuring 3.0 x 3.0 m). Three of the 3.0 x 3.0 m bedrooms have brick birthing dens measuring 1.5 x 3.0 x 1.5 m with entrances measuring 1.5 x 1.8 m. The animals are separated from the keepers by wire.

It should be noted that the Polar Bears are kept separately from other carnivores, surrounded only by birds, and the bedrooms and birthing dens are isolated from the public, so that the level of city noise there is decreased.

The diet of the Polar Bears at the Moscow Zoo is represented in table 4.

Table 4. Polar Bear diet at the Moscow Zoo.

Food item	Winter	Summer
	Per animal per day in kg
Meat	3.0	3.5
Fish	4.5	4.75
Rye bread	3.0	3.0
Oatmeal	1.0	1.0
Carrots	1.0	1.0
Lettuce	1.0	1.0
Bone meal	0.02	0.02
Feed yeast	0.05	0.05
Cod liver oil	0.05	0.05
Premix (additive)	0.05
Cereal greens	0.03
Total food:	13.97	14.37

While preparing for birth, the female is gradually given less food, and after birth the amount of food is gradually increased until it reaches the amount of the regular diet. The cubs live with the mother until they are almost a year old and are given the same diet, but during the first months when the female begins eating, the meat and fish are cooked, and raw products are introduced gradually. Food for the cubs is also introduced gradually, depending on the amount eaten. During the preparation for breeding, the animals’ main diet is supplemented with vitamins and minerals in cod liver oil, feed yeast and meat-and-bone meal.

Sexual behavior and birth in Polar Bears

The first estrus was noticed when the females were 3.5 years old. The males become sexually mature later, by the time they are four years old. Mating in Polar Bears is observed in the spring, in March and April. At that time the male starts intensive courtship of the female in estrus, but if there is no estrus, the animals remain calm. During the period of estrus the male often sniffs at the female, he follows her all the time, producing bubbling sounds, while his lower lip is extended and protruding. The animals often play with each other, but until the female is ready for mating, she does not let the male come close to her. Mating can take place several times a day, at any time during the day and night. After mating the animals rest. During the breeding season they sleep hugging each other, quite close or not far from one another. After mating, when the breeding season is over, the animals are not separated right away, but remain in the same enclosure. They remain calm and do not pay any attention to each other. They sleep separately and sometimes quarrel over food, while the female that has been bred tries to yield to the male by letting him have the best pieces. In those cases the male is separated from the female earlier, if possible, but usually it is done 1.5 months before parturition. According to our observations, the gestation lasts from 228 to 262 days.

The pregnant female eats well at first, but the closer she gets to the time of parturition, the less she eats, practically refusing food. Pregnant females often rest in the birthing dens, where hay is placed a month before parturition. The females do not scatter hay, but collect it and make nests out of it.

Our females give birth in October or November. Most often it happens in the morning, but it is impossible to determine the exact time of birth, as the females usually give birth in the birthing dens, and only the sounds produced by the newborn signify that a birth has occurred.

Feeding a lactating female.

During the two weeks before parturition the female eats poorly, mostly consuming vegetables, and three days before parturition she stops eating altogether. The digestive tract is being cleaned of food and is plugged up by plant matter.

After the female has given birth, she is not fed, and her den is not cleaned. Nobody enters her enclosure in order not to disturb her. We find out that birth has occurred by the sounds produced by the female and the cubs. From the first day after birth the female has permanent access to running water. When the female leaves the birthing den, usually a month after parturition, she is given a small amount of cooked meat (100 grams) and fish (200 grams). If the female starts eating, the amount of food is gradually increased. The food is placed very carefully in a certain place far from the den, always at the same time, while it is important that the female should leave the den and wait to be fed. If the female starts showing signs of anxiety, the keepers immediately leave quietly.

Behavior of females and cubs.

As it is impossible to completely exclude all disturbances of lactating females in a zoo, and also because of the close proximity of the males, the females start leaving their dens already a month after parturition. They leave the cubs for short periods of time after having covered them with hay. During these outings we feed the female, and if she doesn’t show any signs of anxiety, we try to observe the cubs. We succeeded in seeing the cubs for the first time when they tried to climb out of the den at 1.5 months of age. In order to prevent the cubs from leaving the den too early, the female piles up hay in front of the exit. At the age of two months the cubs can already move well around the cage and try to eat the food that is given to the female.

When the cubs are four months old, they gain access together with the mother to the outside enclosures with pools filled with water. At first the cubs have a great fear of water. The females try in every way to entice them into the pool, but the cubs stay on land or play in the shallow water. Gradually they become more comfortable and get more and more interested in the water, dipping their faces in and splashing water with their paws. This behavior lasts for about a week. At some point the cubs work up enough courage and jump into the deep pool, but immediately climb out onto land. Initially they swim poorly, but they play in the water more and more often. Soon the cubs can swim and dive well. During all this time the female constantly observes them, helps them to climb out of the water and sometimes takes part in their games. The cubs remain with the female until they are almost a year old.

During the last ten years the Moscow Zoo had two fatalities in Polar Bear cubs. We believe that the first one was caused by the female being disturbed by a sharp loud sound that made her leave the den on the ninth day after parturition, which resulted in the cub’s death. The second case involved the offspring of the other female. One of the cubs fell into the pool that had been drained of water, and was killed. After the cubs’ deaths the females remained subdued for two to four days, looking for the cubs and producing crying calling sounds. Females display similar searching behavior and refuse food after the cubs have been taken away. If during this time the female is placed together with the male, she displays aggression towards him. The males do not confront the females in this condition, but run away, hiding in the pool filled with water. This anxiety in the female can last up to four days, and then her behavior becomes normal.

Information on the breeding of Polar Bears at the Moscow Zoo from 1998 to 2004 is represented in table 5.

Table 5. Breeding of the Polar Bears at the Moscow Zoo from 1998 to 2004.

Mother (Name and #)	Father (Name and # )	Date of mating	Date of birth and number of cubs	Date cubs shipped out and receiving zoo
Murma 1202	World 0865	12.03.98	14.10.98 1/0	27.12.99 Guangdong (China)
		10-15.03.00	16.10.00 2/0	Died on 10.02.01 08.11.01 Karlsruhe (Germany)
	Umka 1618	08.05.03	26.11.03 1/0	24.12.03 Doltsau (China)
Simona 1616	Wrangel 1201	08-15.04.99	03.12.99 1/0	Died on 12.12.99
		10.04.00	20.11.00 2/0	31.05.02 to Beijing 24.06.02 to Asahikawa (Japan)
		08-10.04.02	21.11.2002 1/1	0/1 17.11.03 Wuppertal (Germany)

Thus, despite considerable psychological pressures (the Zoo is located in the middle of a noisy city, and the number of visitors reaches three thousand people a day), it can be considered that our Polar Bears have adapted well to their captive environment. At this time, the bears have formed two successfully breeding pairs: Wrangel-Simona and Umka-Murma.

After reconstruction the Moscow Zoo resumed its work on the preservation and breeding of Polar Bears in captivity.

Literature

Сосновский И.П. История зоологических парков мира. Зоопарки и их роль в сохранении диких животных.
Сборник научных трудов, изд. Кайнар, Алма-Ата, 1989,
с.3-13.

Sosnovsky I.P. History of Zoological Parks of the World. Zoos and Their Role in Wild Animal Conservation.

Scientific proceedings, Kaynar Publishing House, Alma-Ata, 1989, pp. 3-13.

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