Our hamsters have only been in captivity for a relatively short time, so it is useful to know what their natural life in the wild is like. This may help us to understand and look after them better.
Let us first consider where they come from and their surroundings. Syrians lived in the Middle East in an arid country that is mainly desert or rather bare rocks, without a great deal of difference between the seasons. The days are hot and the nights cold, and food and water are scarce, so hamsters are nocturnal, living below ground to avoid the high daytime temperatures. Dwarf hamsters come from much colder regions.
The Campbells (or Djungarian) hamsters are from Mongolia, where they live among semi-deserts and sand dunes. There are few humans there, only nomadic sheep herders in summer. Temperatures fluctuate between daytime 100 degrees fahrenheit down to 40 degrees at night, and the winters are very cold. They are well adapted to cold with the entire body, feet included, covered in fur. They emerge just before sunset, forage for six or seven hours and return at dawn. They are most active between six and seven p.m.
Winter Whites, or Siberian hamsters as they are known in some countries, come from even farther North, mainly from Siberia although their territory overlaps with that of Campbells. The climate is also extreme. They live on flat steppes covered in short grass which are mainly agricultural, although they make their homes in pockets of land that are ungrazed or untilled. The land is sparsely populated, so both species are unafraid of humans. In the winter snow, they can change colour to white to avoid detection.
Roborovskis live mainly further south, but again on flat, sandy soil. They get up later in the day and are at their most active between nine and ten p.m.
Chinese hamsters come from a little further East, where it is more populated and stony. They have a more erratic activity time, being most active in evening and early night. They are able to climb in the more rocky terrain and have short tails which help them to grip. The climate is warmer, and they are not so well adapted to extreme cold.
The burrows of the species differ and are suited to the terrain in which they live. Syrians have burrows up to ten metres deep with several entrances which they dig in the sandy soil. The depth of the burrow protects them from the daytime heat. They are solitary animals by nature. Each hamster has its own burrow with surrounding territory. Campbells don't dig their own burrows in the hard ground, preferring to take over those left by other rodents.They break down the soil at the entrance to make several vertical escape and ventilation tunnels about one and a half inches in diameter and around four feet in length. They live in the original nest chamber which is about the size of two human fists. Just before giving birth, the female will build a special nest chamber which she will line with dried grass, or sheep's wool if she is lucky enough to find some. Chinese hamsters have less vertical burrows, often using natural holes and spaces among rocks, but often with two entrances. The burrows are near the surface, so Chinese tend to move quickly and are more nervous. If disturbed, they will either run or remain absolutely still to avoid detection. Roborovskis have very shallow tunnels, usually just below the surface with a single entrance.
The less well known mouse-like hamsters come from Afghanistan where they live among pine and cork oak covered slopes, using cracks in the rocks as communal nests which they line with sheep's wool.
Syrians hamsters are solitary dwellers and the females are larger and dominant. They will lure males to their nests for mating using scent and after mating drive him away. The young leave the nest after weaning when they are at their most vulnerable to predators such as birds of prey and desert foxes. They are therefore very nervous, and dislike shadows from above.
Russian Campbells live mainly in pairs. The ranges of females do not overlap and those of males do so only if they are visiting the same female. A female usually has a smaller range than that of the male, and it is inside the male's territory. Whilst they may share the burrow with a male, they may also be visited by other males from up to a mile away, for mating. These males often fight. As the winters are cold and food scarce, they have litters in close succession in the summer. Females may mate when they are as young as 35 days old, and then mate again on the night of the birth of a litter before lactation begins. After three or four litters, the female may die from exhaustion or become infertile. All breeding is controlled by hormones, on a strict timetable. Females are able to regulate reproduction including the timing and number of young. During the breeding season they require large amounts of protein, up to 60% of their diet. For the first twelve days of their lives the young cannot control their body temperature, so an adult needs to be on the nest and the father(s) or siblings are vital for the care of the offspring. The babies cannot grow if they are cold and as litters are born in such quick succession, they need to grow fast. If the father is present, 95% of the young are likely to survive, but if the female is alone only 47% live. This increases to 61% if an aunt or older sibling is present. The gestation period is short, 16 to 18 days on average, but may be as little as 13 days.
Winter Whites have more complicated lives. Each female shares separate burrows with at least two males, and each male will share with at least two females. Each pair has only one shared burrow, but each will also have a different burrow shared with another mate. When the female is ready to mate she moves from the one male to the other during that night. Again, the males share the care of the young, and if the males are killed or removed after mating, the eggs will not stick to the womb.
Roborovskis only breed during the very short summer, in June and July, having two or three litters closely together. The young born from the first litter are ready to produce young themselves by the end of that breeding season, but those from later litters will not have young until the following summer.
All these hamsters live on a mixed diet, eating what can be found in the dry areas they inhabit, consisting mainly of grasses and seeds plus moths, beetles, grasshoppers and other insects. They will eat eagerly any dead birds or animals that they find. They may have to range over wide distances in search of food, carrying it back in pouches to be stored in caches that are eaten later when times are hard. Winter Whites that live near agricultural and pastoral land find much of their food from drying cow pats which contain undigested seeds. This dung must be found when it is not too fresh or else it sticks to their fur, nor must it be too hard.
All the Russians use special marked highways that cover long distances. They are marked by scent, as the hamsters are small and cannot see very far ahead. They have at least six chemical signals coming from glands behind the ears, at the corners of their eyes, the entrance to the pouches, the abdomen, from the faeces and urine and in the females, from the vagina. They carry a map of the routes in their heads. They mark the entrances of their burrows by ritualised grooming, rubbing their paws over the ears, around the eyes and by scratching and rolling. The scent is transferred to their furry paws so that every step they take is marked. This scent lasts at least eight days. Another hamster coming to a grooming place will roll there to add its own scent.
Thanks in particular to Katherine Wynne-Edwards for permission to use information from her article in BBC Wild Life magazine and to Fred Petrij and Rob Dekker from their book on dwarf hamsters.