Grazed crop losses reach £100m a year
Grazed crop losses reach £100m a year
CROP losses due to rabbits, often underestimated by farmers, are now reckoned to be £100m a year.
Populations are back to 35-40% of pre-myxomatosis levels nationally and increasing at 2% a year, says CSL researcher Gordon McKillop.
On winter wheat, one grazing rabbit can cut output by 65kg, equivalent to £7.50 a rabbit, Dr McKillop suggests. Multiply that by a typical rabbit grazing population of 40/ha – commonplace in much of lowland England – and the overall loss adds up to £300/ha (£120/acre).
Grazed winter wheat plants tend to recover in the late spring and summer, leading many farmers to under-estimate the extent of their losses, he comments. But grazed plants go on to produce fewer ears and fewer grains per ear. Grain quality is not affected.
First year results of research to measure the effects of rabbit grazing on spring barley suggest a yield loss of 30kg of grain a rabbit, or £3.90. In perennial ryegrass the loss is put at 130kg wet weight, or 20kg of dry matter worth £2 a rabbit.
Dr McKillop believes those figures can be used to judge whether it is cost effective to control rabbits in a given situation.
Gassing is still the preferred method of rabbit control, and probably so efficient because it targets female rabbits, suggests further CSL research.
Results from the excavation of seven warrens after normal gassing procedures in the winter of 1995-96 were reported by CSLs Graham Smith. Four of the warrens were found to contain three new-born rabbits, five juveniles and nine adults. Significantly, only one of the juveniles was a male. All the adults were female and all showed signs of pregnancy or lactation. *