sentences:  Conversely, the number of hares and rabbits have tended to decrease.The reason seems to be the outbreak of myxomatosis in 1953 that caused havoc in the population, and, since the end of the 20th century, Rabbit haemorrhagic disease causing the decline of the species.The scarcity of these rodents could pose longer term problems for the survival of species of birds of prey that feed on them.