Experimental Ecological Studies on a Subalpine Rabbit Population I. Mortality Factors Acting on Emergent Kittens

Abstract

In the first of three studies on the causes of mortality and the physiological status of emergent kittens of Oryctolagus cuniculus (L.), the time and place of death were detected by means of radios attached to the animals. The overall mortality rate of 2.7% per day was due to mammalian predators (1.5% per day), birds of prey (0.7% per day) and to other unidentified causes. In a second study, using different techniques, a similar estimate of bird predation was obtained. In the third study the effects of birth date and population density of kittens on a range of physiological measures were tested. Density, over the range used, had little effect on the physiological status of the animals, but the birth date significantly affected the growth rate and the proportion of lymphocytes in the white blood cell count. The animals born later in the season also suffered from mild macrocytic anaemia.