No evidence of negative effects of aerial 1080 operations on red deer (Cervus elaphus) encounters and sightings in South Westland forests

Recreational hunters are concerned that aerial 1080 operations in New Zealand’s forests may adversely affect deer hunting, but data are rarely gathered in a way that enables such effects to be assessed. Between 2011 and 2015, we recorded two relevant indicators of the recreational hunting experience – number of red deer (Cervus elaphus) encounters, and number of individual red deer seen – in 865 person days of quarterly surveys across seven blocks of native forest in South Westland, New Zealand. Four blocks were treated with aerial 1080 before and during the study, and three were untreated. Generalised linear mixed effects models provide no evidence that aerial 1080 treatments reduced numbers of red deer encounters or numbers of individual red deer seen over time. There were no overall trends in numbers of deer encounters and deer seen per person day in either treated or untreated blocks over the study period, and average numbers of deer encounters and deer seen in treated and untreated blocks were similar. Models fitted to data from the 1080-treated forest blocks alone showed that numbers of deer encounters and numbers of deer seen per person day were highest in the period immediately following an aerial 1080 operation and declined over the following 2–3 years. This pattern is likely to result from a change in deer behaviour rather than in deer numbers, and its cause is unknown.