Department of Conservation (DOC) staff are out in the field in Northland monitoring tracks and waterways after the region's first major 1080 drop in decades.
The aerial pest control operation went ahead at the weekend over Russell State Forest and Cape Brett, despite a last-minute bid to stop it in the Māori Land Court.
A DOC spokesperson said staff were now taking water samples and picking up any baits that fell on walking tracks.
They were also collecting any dead animals found in waterways to stop them from washing downstream.
In Cape Brett forests, hapū who supported the operation were doing the job.
DOC said the weather was fine for the 1080 drop and it was expecting a good kill rate of pests that have brought the forests to the point of collapse.
Monitoring beforehand showed 80 percent of tracking tunnels were visited by pests.
DOC said a forest where possums, rates and stoats were under control would show a hit rate of under 5 percent.