This report covers the findings from the year of flesh-footed shearwater (Ardenna carneipes) research under Conservation Services Programme (CSP) project POP2021-04 for the 2022/2023 season, funded by Department of Conservation (DOC). Here we report on the ongoing population monitoring of flesh-footed shearwaters on Ohinau Island.
During the 2022/23 season WMIL monitored 271 study burrows on Ohinau Island. The breeding success (burrows with an egg that produce a chick that is likely to survive to fledging) on Ohinau Island was 10%. This represents a large decrease compared to the 59% measured in the 2022/23 season. This is postulated to be because of the significant storm events that occurred in the region just after peak laying (December 2022 through to February 2023), and therefore as a result of climate change. There was a detectable difference in breeding success between study and burrowscope (control) burrows, indicating potential impact of handler disturbance. However, it is believed this is more likely due to the topography and location of the burrowscope colony compared to the other colony sites, which allowed these burrows to avoid the worst of the flooding. We were able to identify 51.5% of the birds in breeding study burrows on Ohinau Island. An additional 75 flesh-footed shearwaters were banded on Ohinau Island this season, with 47 adults and 28 chicks.
Due to weather constraints that led to 8 days being lost during the January 2023 expedition, an updated population estimate for Ohinau Island was unable to be completed. WMIL has recommended that the limited data that was able to be collected, not be used for the purposes of calculating a population estimate. Instead WMIL recommends postponing this work until the 2023/2024 season.
WMIL recommendations include:
- Population monitoring on Ohinau and Lady Alice Islands be continued with 200 breeding study burrows monitored annually over two expeditions (Dec/Jan and Apr/May).
- The number of burrowscope burrows monitored annually continue to be 50 on each island.
There is continued, focused effort to band and recapture as many flesh-footed shearwaters on the surface and in burrows on both islands.
Titi Island, Marlborough Sounds, be considered as a potential future monitoring location.
- A repeat population estimate on Ohinau Island be undertaken in January 2024.
- Undertaking plastic collection from the surface of colonies, necropsy of dead individuals found at colony sites, as well as the lavage technique to understand more about plastic ingestion.
- A survival analysis be undertaken to estimate adult survival on each island.
Ray, S. and Burgin, D. 2023. Flesh-footed shearwater population monitoring and estimate Ohinau Island: 2022/23 season. POP2021-04 final report prepared by Wildlife Management International Limited for the Department of Conservation. 50 p.