Wild Rabbits Thrive In Crowded Conditions

Press, Issue 29236, 21 June 1960, Page 13

Wild Rabbits Thrive In Crowded Conditions

••Ths Press" Special Service

WELLINGTON, June 20.

Crowding results in an improvement in the condition of the wild rabbit in New Zealand, scientific investigation has found. An intensive study was recently carried out by the animal ecology section of the Department of Scientific and Industrial Research, to find out whether population density had an effect on rabbits.

Summarising the findings, Dr. K. Wodzicki, officer in charge of the section, and Mr H. S. Roberts, of the department’s applied mathematics laboratory, said that it was suggested that a fairly high population was essential for the rabbit’s welfare. A total of 523 European wild rabbits from four controlled populations ranging from one rabbit to five acres up to 23 rabbits to one acre, in the North and South Islands, were examined. Their sex, age, body and adrenal weights and the amount of fat were recorded. Heavier in South Island

The season of collection did not affect the body weight. Rabbits from Gore were, however, significantly heavier than those collected from the Wairarapa at the same season and from population of similar density. Increasing population density did not lead to any noticeable

stress, as with rats or mice. On the contrary, the rabbits* condition, as evinced by fat content, improved. It was surprising to find that rabbits at a density of 23 to the acre were in better condition than those at lower densities. The suggestions of other previous workers had been that social habits might require a certain minimum population density for the wellbeing of the population. Other observations had suggested that in New Zealand climatic conditions of a medium rainfall, only in dense populations could rabbits produce and maintain the neatly-cropped short grass and some bare soil, which seemed essential for their wellbeing. In a preliminary report on age determination in wild rabbits, Mr R. H. Taylor, of the animal ecology section, described ways in which age was assessed. Population studies of the wild rabbit in New Zealand and elsewhere had emphasised the need for reliable methods of age determination, he said.