CBAC Mohua Methodology
Each CBAC Mohua enables the maintenance of one trap which protects 15 hectares of Mohua habitat.
1 credit = $200 = 15 hectares of protection
Mohua are endemic to the South Island and are nationally endangered. Their population is less than 5,000 and is in decline. One of the remaining Mohua populations is located in the Makarora, Blue and Young valleys. This small population is seriously threatened by rats and stoats, which predate on their eggs and young.
Mohua are known for their machine-gun-like chatter and bright yellow colours. They are one of New Zealand's smaller endemic birds, with males weighing up to 30 grams and females just 26 grams.
Mohua have been monitored in the Makarora area for the past 12 years, using encounter rates along transects. Following a dramatic decline in the initial two years, mohua encounter rates have gradually increased until 2020 and have been declining slowly since then. Mohua are still scarce and patchily distributed. During the 2021 survey, there were approximately 10 mohua in the Muddy Creek area and up to 20 on the true right of the Makarora. However, recent incidental surveys have not identified this many birds.
Rat numbers have been increasing since 2023. An extensive amount of predator control work happens throughout the year conducted by Southern Lakes Sanctuary in partnership with Forest and Bird and the Department of Conservation, servicing 1,066 rat and stoat traps on public conservation land. These traps achieve an effective area of 15,980 ha of suppression. Over the past year, over 2,500 pests have been removed, including 1730 rats. In the past month (July 2023), 392 rats have been removed from the trap network, compared with 54 rats during the same period in 2022 - showing a significant spike in rats being caught in 2023 - highlighting the need to continue with this work.
Funds from your credit purchase will support the maintenance of established trap networks with monthly trap checks, annual trap calibration and data collection, along with predator presence monitoring and native species monitoring.
One credit protects 15 hectares of habitat from mustelid species (stoats, ferrets and weasels) using DOC 200 traps and from rats using monster and Victor traps. While the mustelid traps also will catch rats, rats are one of the other key threats to mohua, and there is a need to have a combination of both traps.
This project uses one stoat trap per 20 hectares which is informed by the latest conservation science and DOC recommendations. Rat traps are intermittent throughout the project based on areas the project managers have identified are most likely to have high rat populations.
Because stoat and rat traps are throughout the same area, I.E., the 15-ha radius from each trap can overlap, each credit ownership entitles the owner to one trapping location. They are also able to claim the beneficial owner of the impact of suppressing 15 hectares of mohua habitat from predators. This 15 hectares is not the radius around your trap but 15 hectares within the trapping network.
The primary species that this credit is for is Mohua. However, there are also Whio, Kea, Kaka, Wrybill and Banded Dotterel in the area that benefit from these credits.
Funds from your credit are required to be spent on
Transport, including helicopter use
Monitoring equipment (cameras, SD cards, tracking tunnels)
Bait, lure and trap maintenance supplies
Staff health and safety equipment
Field crew wages
Project support costs
As part of the Mohua project, there is annual predator monitoring, including:
5 x ridge-to-river tracking tunnel sets (that are done 3-4 times per year); these are located throughout the project area. These are completed by DOC. However, Southern Lakes Sanctuary staff have been assisting with this monitoring while DOC staff numbers were low;
Residual Trap Catch Index for rats. This is completed monthly from Trapnz data and measures rat indices;
Southern Lakes Sanctuary will be completing additional predator monitoring with motion sensor cameras (and moto-lures) and chew cards (wag tag indexing) for possums in the Makarora project area during the 2023/2024 summer field season.
with motion sensor cameras, tracking tunnels, chew cards, eDNA, RTCI and observations.
Monitoring for Mohua and other native bird species in the area includes;
Transect surveys for mohua - 10 fixed transect lines have been surveyed each year since 2011, with 3 lines added in 2013. These surveys are completed in spring by DOC (Southern Lakes Sanctuary staff completed these on behalf of DOC in 2022); 2022 report: 2022-transect-survey.-SLS-Final-V2.pdf (southernlakessanctuary.org.nz);
Analysis of Makaroa mohua encounter rates (Mohua_analytical_report_final.pdf (southernlakessanctuary.org.nz)).
Distribution survey in 2021 (completed by Southern Lakes Sanctuary): Makaroa-Mohua-Distribution-Survey-November-2021.pdf (southernlakessanctuary.org.nz);
Mohua nest monitoring with acoustic monitoring devices (with analysis software program Kaleidoscope), initial surveys were completed in 2022 by Southern Lakes Sanctuary (in association with Dr. Laura Molles). The project will expand during the spring of 2023 to include the banding of birds and the collection of significantly more recordings. The aim of the project is twofold, first, to develop a survey method that will be able to identify individual mohua (through acoustic recordings) without the need for more invasive techniques and to gain a better understanding of the mohua population in Makarora.
Whio surveys of the Leven, Ore, Stag and upper north creeks/rivers are planned for the summer 2023/2024 season (this will be completed by Southern Lakes Sanctuary);
Environmental DNA monitoring of creeks to provide a snapshot of species that may be in the area and the overall health of the creek ecosystem - this is planned for summer 2023 and will likely include the Leven, Ore, Stag and Young creeks/rivers.
Bat acoustic monitoring/surveys will be completed by Southern Lakes Sanctuary this summer season.
Transects, species-specific surveys, 5-minute bird count, automatic acoustic monitoring devices and motion sensor cameras.
Updates on the project are sent annually to credit owners.
Date - Sale 1 Sept - End 2023
Credit action 1 Jan - End of 2024