Saiga are nomadic animals and undertake seasonal migrations from summer pastures in steppe grassland to winter pastures in desert areas (8). Large groups of saiga migrate southwards to the winter grounds, covering up to 72 miles in a day (6). The rut begins in late November and males gather groups of around 30 females in 'harems', which they defend aggressively (5). During the rut, males' noses swell up and the hair tufts below the eyes are covered in a sticky secretion (2). Males do not feed much during the rutting season, when they take part in violent fights that often end in death. The male mortality rate can reach 90 percent during this time, due to exhaustion (5). Surviving males begin to migrate north at the end of April (6). Females give birth at this time, usually to two young, which are initially concealed in vegetation; all the females within the herd will give birth within a week of each other (6). Once the calves are a few days old, the whole herd breaks into smaller herds which head northwards to the summer feeding grounds (9). Once there, smaller groups break off, reforming again for the journey south the following autumn (6). Saiga graze on a number of different grasses, herbs and shrubs (1). The unusual swollen nose is thought to filter out airborne dust during the dry summer migrations and to enable cold winter air to be warmed before it reaches the lungs (6).