Irish elk
At Ballybetagh Bog, over 100 Irish elk individuals were found, all small antlered bucks. This indicates that bucks and does segregated during at least winter and spring. Many modern deer species do this in part because males and females have different nutritional requirements and need to consume different types of plants. Segregation would also imply a polygynous society, with stags fighting for control over harems during rut. Because most of the individuals found were juvenile or geriatric and were likely suffering from malnutrition, they probably died from winterkill. It is possible that most Irish elk specimens known had died from winterkill, and winterkill is the highest source of mortality among many modern deer species. Bucks generally suffer higher mortality rates because they eat little during the autumn rut. For rut, a lean stag normally may have fattened up to , and would burn through the extra fat over the next month.