Home ranges and movement of sika deer (Cervus nippon) in central North Island, New Zealand

Sika deer (Cervus nippon) were introduced into the central North Island, New Zealand, in the early 1900s. They rapidly established, increased in numbers, and extended their geographic range, eventually displacing sympatric red deer (Cervus elaphus). Sika deer are an important game species, but they can also severely damage native forest, especially where they occur at high densities. Here, we provide the first comprehensive assessment of annual and seasonal home range and movement ecology of adult male and adult female sika deer in New Zealand. Using kernel density estimation, we found that the average annual home range size of males (mean = 446.5 ha, SD = 273.0) was significantly larger than that of females (mean = 77.0 ha, SD = 48.6; Mann–Whitney U = 6, p < 0.05). This pattern was consistent across seasons, but was least pronounced in spring and most pronounced in autumn, when males seek mating opportunities. We found some males moved between non-overlapping seasonal ranges, whereas no females displayed this behaviour. On average, males used slightly higher elevations (c. 80 m higher) than females in all seasons, but there was high individual variability for both sexes. We did not find evidence that sika deer in central North Island make altitudinal migrations to avoid inclement weather in winter like sika deer do in colder regions of their native range. Information about home range and movement ecology can guide management strategies that aim to prevent further geographic spread of sika deer from their current range in the central North Island.