Context The risk of secondary poisoning to native fauna during pest control operations is an issue of global concern. In New Zealand, non-target impacts during sodium fluoroacetate (1080) operations are particularly contentious. 1080 is used extensively for pest control for conservation, bovine tuberculosis control, and in plantation forestry for seedling protection from herbivores. The endemic New Zealand falcon (Falco novaeseelandiae) breeds in Kaingaroa forest, an intensively managed pine plantation where regular 1080 poison operations are conducted; however, causes of mortality and risks of secondary poisoning by 1080 are not well documented. Aims We aimed to investigate mortality and survival of adult falcons with an emphasis on assessing the possible role of 1080 poisoning in annual mortality. Methods Using radio-telemetry and visual observations, we monitored 37 marked adult falcons before and after 1080 operations in 2013–14 (16 through carrot-bait and 21 through cereal-bait operations) and assessed mortality causes through post-mortem examinations. Using Program MARK, the annual survival rates for adults and independent juveniles were estimated from long-term banding data (2003–2014). Key results Survival of falcons was high through both cereal-bait (21/21) and carrot-bait (15/16) 1080 operations (overall 95% CI for survival = 84–100%). The exception was a radio-tagged male that died of unknown causes within a fortnight of an operation and tested negative for 1080 residues. Three falcons were depredated by introduced mammals. One falcon was found dead in an emaciated condition but evidently died from head injury through Australasian magpie (Cracticus tibicen) attack. The annual survival rate of falcons estimated from long-term banding was 80 ± 6.0% (mean ± s.e.) for adults and 29 ± 0.1% for juveniles. Conclusions No adult falcon death was attributable to 1080 poisoning in this study. Identifiable mortalities were attributable to depredation by introduced mammals and an injury from an Australasian magpie. The annual survival rate of Kaingaroa falcons was comparable to those of other raptor species worldwide. Implications The risk to adult falcons from 1080 secondary poisoning is likely low. Whether this is also true for juveniles requires further study.

Previous breeding‐season studies of threatened New Zealand falcons (Falco novaeseelandiae) in plantation forests have suggested that falcons benefit when harvesting creates a mosaic of differently aged stands, especially where young and mature tree stands are adjacent. Thus, changes in the rate and pattern of harvesting may affect habitat heterogeneity by altering the size and distribution of forest patches. We sought to determine guidelines for harvesting that would most benefit falcons by increasing the carrying capacity of the forest for falcons. We used radio‐tracking to determine the home‐range sizes of non‐breeding falcons over 3 seasons and compared winter home‐range overlap in the most‐selected land cover types by falcons (mature‐young edges and open patches) with other land cover types. The distribution of open patches and edges between mature stands and recently cleared areas affected falcon home ranges, home‐range overlap, and the likelihood of nesting. Specifically, home ranges were smaller as the density of edges and percentage of open patch increased, and there was greater home‐range overlap between individuals in the most‐selected land cover types. Numbers of falcons decreased as the size of open patches increased, concomitant with a decrease in edge size, the number of edge borders, and the number of open patches. The likelihood of nesting also decreased as open patch size increased. Our results indicate that smaller open patches spread through a forest, maximizing the amount of mature‐young edges, will favor smaller home ranges and therefore potentially greater numbers of falcons. We recommend harvesting protocols that ensure that open patches (0–3‐yr‐old stands) are <4 km2 in size and retain at least small stands of mature pine to maintain a high density of edges. Similar protocols may increase the carrying capacity for other species occurring in managed systems involving fragmented landscapes or small reserves. © 2021 The Wildlife Society.