Reproduction in the European hare in southern Sweden

Abstract

Reproduction in the European hare Lepus europaeus Pallas populations was studied in three study areas in South Sweden during 1974–1976; two on the mainland and the third on the Island of Ven in Öresund. The monthly birth rates was calculated on the basis of the age of juvenile hares shot in autumn. The first births always occurred in February, indicating that the onset of the breeding season was governed by day length rather than by climate. Later, the reproduction rate was determined by temperature, snow cover, and precipitation. Low temperatures in spring delayed the reproduction; high temperatures in autumn favoured a prolongation of the breeding season. Low precipitation in May‐July caused a decline in reproduction in July in a sandy pasture area, mainly because water amount was low in the green forage. Annual fertility, estimated on the basis of placental scars, varied between 6.8 and 8.9 young per female. There was a significant negative correlation between fertility and population density. The largest variations were recorded in one‐year‐old females, and on average the values were significantly higher in three‐year‐old females. 68% of all females examined had three litters annually; four litters were found in only 13% of all females. The mean litter size for the whole period was about 2.9 in all areas. The size of the first litter was significantly higher in females producing one or two litters than in females with three or four litters. The postnatal losses were on average 30–35% lower in the island population than in the mainland populations (73–84%), probably due to lack of predators, sparse road traffic, and inhibited juvenile dispersal.