Philip J. Seddon

Individual‐level differences in animal spatial behavior can lead to differential exposure to risk. We assessed the risk‐exposure of a reintroduced population of kākā ( Nestor meridionalis ) in a fenced reserve in New Zealand by GPS tracking 10 individuals and comparing the proportion of each individual's home range beyond the reserve's fence in relation to age, sex, and fledging origin. To estimate dynamic space use, we used a sweeping window framework to estimate occurrence distributions (ODs) from temporally overlapping snapshots. For each OD, we calculated the proportion outside the reserve's fence to assess temporal risk exposure, and the area, centroid, and overlap to represent the behavioral pattern of space use. Home range area declined significantly and consistently with age, and the space use of juvenile kākā was more dynamic, particularly in relation to locational changes of space use. The wider‐ranging and more dynamic behavior of younger kākā resulted in more time spent outside the reserve, which aligned with a higher number of incidental mortality observations. Quantifying both home range and dynamic space use is an effective approach to assess risk exposure, which can provide guidance for management interventions. We also emphasize the dynamic space use approach, which is flexible and can provide insights into a species' spatial ecology.

Invasive mammal eradications are increasingly attempted across large, complex landscapes. Sequentially controlled management zones can be at risk of reinvasion from adjacent uncontrolled areas, and managers must weigh the relative benefits of ensuring complete elimination from a zone or minimizing reinvasion risk. This is complicated in urban areas, where habitat heterogeneity and a lack of baseline ecological knowledge increase uncertainty. We applied a spatial agent‐based model to predict the reinvasion of a well‐studied species, the brushtail possum ( Trichosurus vulpecula ), across an urban area onto a peninsula that is the site of an elimination campaign in Aotearoa New Zealand. We represented fine‐scale urban habitat heterogeneity in a land cover layer and tested management scenarios that varied four factors: the density of possums remaining following an elimination attempt, the maintenance trap density on the peninsula, and effort expended toward preventing reinvasion by means of a high‐density trap buffer at the peninsula isthmus or control of the source population adjacent to the peninsula. We found that achieving complete elimination on the peninsula was crucial to avoid rapid repopulation. The urban isthmus was predicted to act as a landscape barrier and restrict immigration onto the peninsula, but reliance on this barrier alone would fail to prevent repopulation. In combination, complete elimination, buffer zone, and source population control could reduce the probability of possum repopulation to near zero. Our findings support urban landscape barriers as one tool for sequential invasive mammal elimination but reaffirm that novel methods to expose residual individuals to control will be necessary to secure elimination in management zones. Work to characterize the urban ecology of many invasive mammals is still needed.