The comeback of the rabbit-killing virus RHD during summer helped prevent what could have been a "very serious" rabbit explosion in Otago, Otago Regional Council regional services group manager Jeff Donaldson said.
Otago regional councillors this week discussed a serum testing report on the presence of the rabbit haemorrhagic disease (RHD) in the region's rabbit population.
It showed that while there was high immunity in the rabbit population, the virus still killed large numbers of rabbits.
Chief executive Graeme Martin said there was "quite a remarkable" death rate during summer due to the virus and other diseases which came with weather conditions.
The virus, which was introduced in 1997, had appeared in varying levels every season since then and when environmental conditions were favourable it could have a significant effect on the rabbit population.
Mr Donaldson said there were two variables involved this season: an amazing breeding season for rabbits, and the virus' remaining in circulation much longer than normal.
"It helped us. The rabbit explosion we could have had could have been quite serious."
However, because the virus continued to be active during the February-March testing stage, it meant immunity levels in rabbits were going to be higher.
Despite the strong showing by the virus this season, secondary control was still believed to be important if landowners were to control rabbit numbers, he said.
"They need to recognise [the virus] is not a silver bullet but a tool, and using secondary control methods with the virus will reduce the rabbit population."
The virus' presence did help keep the cost of controlling the population down, Mr Donaldson said.
A significant amount of research was being done on the virus, which the council was keeping a close eye on, and the identification of fly strike as an indicator could be a good tool.
Cr Doug Brown said ultimately, the virus had not done much to the rabbit population, and secondary control was still necessary.
The committee agreed the council should continue its biennial RHD serum testing programme.
