They’re killing possums in the Town Belt. Possums are a pest in New Zealand and we need to get rid of them in order to allow the native birds to return. Apparently:
The Australian brush-tail possum was brought to New Zealand a century ago to establish a fur industry. Possums have decimated native wildlife, destroyed native forests, ruined crops and spread bovine tuberculosis.

While we’re warned to keep dogs away this stuff isn’t any good for cats either. How do I tell my three cats to stay away from whatever they shouldn’t eat — rat carcasses, for example.
A young looking dead possum.
This possum’s quite small and probably quite young. The poisoning’s working.
Updated October 2012 to replace lost photos.