A tactic to protect monarch butterflies in local parks from predation by rats has been given the green light.
The Social, Community Development and Housing Committee today approved a proposal to install pest-proof steel bands on trees in Abberley Park and Burnside Park before the butterflies start their overwintering behaviour.
This is when they roost in large numbers on tree branches.
Strategic tree banding was proposed for a number of overwintering trees by Christchurch City Council Ecologist Antony Shadbolt and Vicky Steele of advocacy group Project Wingz, who say the banding is likely to prevent significant monarch mortality at the parks. It is also a relatively cost effective measure, at about $1500.
Council staff were alerted by members of the community to high monarch butterfly mortality at some parks in winter 2016 and 2018.
Investigation showed they were likely to have been killed by black rats which are good climbers.
Dr Shadbolt says butterfly mortality at the sites will be monitored after the bands are put in place and compared with non-banded sites to assess the measure’s effectiveness.
Committee Chair Phil Clearwater says the plan is a good example of community groups getting involved and collaborating with the Council for a common aim.
The report presented to the committee by Dr Shadbolt and Ms Steele says monarchs are not considered to be a threatened or at-risk species in New Zealand but their overwintering sites are a novelty in urban parks and their presence supports Christchurch’s Garden City image and identity.
They are also one of the first wildlife species that young children recognise and are captivated by.
In addition to tree-banding, winter flowering plant species will be planted in the parks to help improve the butterflies’ survival rates.