Holarctic Marmots as a factor of Biodiversity.
Rumiantsev V.Yu;, Nikol'skii A.A. & Brandler O.V. eds.,
3d Conference on Marmots (Cheboksary, Russia, 25-30 August 1997),
Moscow ABF 1997, 216p. : 176-177.
ON CANNIBALIZM OF STEPPE MARMOTS
Prof. Zhitkov' VNIIOZ,
During a period of 4 years we have been carrying out our observations on steppe marmots in a marmot nursery of VNIIOZ. The total number of marmots was 300 heads. We didn't observe any signs of aggression of marmots to each other during the periode of their catching, transferring in cages with 5-15 animals inside and during transportation by truck. A stock survival was 100%. At a nursery marmots were placed in special cages with a walking site and a house with 2...4 animals per cage.
For 4 years we recorded 21 cases or cannibalism. The peak of cannibalism falls on March-April (11 cases, 52%). At the beginning of hibernation (October-December) 8 cases were recorded (38%). When keeping animals of different sexes in pairs cannibalism was observed both in males and females to an equal extent.
Oniy one case of cannibalism in fingerlings was recorded. At the end of hibernation two fingerlings (a female and a male) ate all viscers in an adult female living with them. Simultaneously they ate a large amount of a hay litter of their cage. Finally both fingerlings died. They had a rectum prolapse. Caecum was entirely filled with densely pressed food.
We are not fully sure that in all cases of cannibalism a live animal was attacked.It is possible that a dead marmot became a prey. We recorded a predatory behaviour in four cases. Here is a typical example. Repeatedly a marmot-cannibal began eating a hibernating marmot and every time the latter woke up. That attack had been lasting for some hours. Later the traces of many bites were seen in the prey. The skin was injured, here and there muscular tissue was seen. Next day that marmot was dead. The bones of vertebral column and thorax were bited through, all viscers were eaten up. Later some "predators" continued eating the prey and left only the fur head bones.
Let's describe the reasons of cannibalism. The deficiency of food resources resulted in that fact that the organism received sufficient amount of certain nutrients that were necessary for hibernation. Among the marmots showing cannibalism 36.4% were with the signs of incomplete moulting. For the rest that index made up 19.8%. That reason resulted in decrease of resistance in marmots. They were prone to diseases more frequently. We observed a diverse respond to infectious diseases. The mazsaots with pasteurellosis become less active, their body temperature sharply decreases and they can't become cannibals. The outbreak of staphylococcosis observed during the first hall of hibernation provoked cannibalism. That disease was accompanied with abscesses that troubled the animals. The animals that had fallen ill awoke out of hibernation and sharply lost their mass. We recorded 14 cases of cannibalism (67%) in animals with staphylococcosis. Cannibalism arises in certain individuals irrespective of the severity of a disease, sex, age and mass of marmots.
In our nursery hibernation took plase under various microclimatic conditions. The temperature in a shed of one group of animals fell below -30oC. A low temperature regime during hibernation didn't cause any departure from the norm in healthy marmots of normal fatness.
To our opinion cannibalism depends on individual features of marmot psychics and is directly related to qualitative composition of food resources during the period of marmot ground activity.