New Zealand Journal of Ecology (1996) 20(2): 285- 288

Short-term effects of rabbit grazing on a degraded short- tussock grassland in Central Otago

Research Article
D. C. Norbury 1,2
G. L. Norbury 1
  1. Manaaki Whenua - Landcare Research, P.O. Box 282, Alexandra, New Zealand
  2. Present address: 13 Kamaka Crescent, Alexandra, New Zealand

Rabbits are serious economic and environmental pests in New Zealand's semi arid lands, yet there is surprisingly little quantitative information about their grazing impacts. This paper describes the shortterm gains in pasture yield following protection from rabbit grazing in a rabbit-prone, dry tussock grassland community in Central Otago. During the four most productive plant growing months of 1994 (September to December), a six-fold increase in pasture yield was observed after protection from rabbit grazing (139 kg dry weight ha(-1) with rabbits cf. 853 kg DW ha(-1) without rabbits). Rabbit counts were 30 to 42 rabbits per spotlight km. The following four months (January to April) were characterised by reduced pasture growth (3 kg DW/ha with rabbits cf. 337 kg DW ha(-1) without rabbits) and higher rabbit numbers (42-76 rabbits per spotlight km), and was a critical period of herbage depletion. These substantial differences in pasture yield indicate the potential benefits for pastoral production and land conservation following protection from rabbits.