Young sparrowhawks (less than one year old) weigh less than adults. They are especially light in the two months after leaving the nest. There is probably a high death rate at this time, particularly for males. This may be because the smaller males catch smaller food. They cannot catch some of the bigger prey that females can. This means they need to eat more often. A female sparrowhawk of average weight can survive for seven days without eating. A male can survive only four days.