Survey duration and season influence the detection of introduced eastern rosella (Platycercus eximius) in New Zealand

Reliable survey methods for detection are critically important for the monitoring and management of exotic species. The eastern rosella (Platycercus eximius), a broad-tailed parakeet endemic to southeastern Australia, was introduced to New Zealand a century ago and is now geographically widespread. We studied the necessary timeframe for surveying the eastern rosella within its introduced range, testing the hypothesis that there are seasonal differences in the likelihood of detection. Although our comparisons were limited to surveys conducted during a single year, they are suggestive of an important impact of season on the survey duration required to detect eastern rosella confidently. Median latency until first detection was less during summer months (2.55 min) in comparison with winter months (11.2 min). Furthermore, 90% of first detections occurred within the first 13 min in summer surveys, compared with 22 min in winter. These results have implications for the design of surveys aiming to monitor rosella populations in New Zealand, and reiterate the importance of tailoring survey methods to the species of interest.