Kereru © James Allan
2nd May 2024
Story by Dawn Palmer, Trustee
We wanted to look at the trap catch information for Lake Hayes Predator Free and compare this to the increase in Southern Crested Grebes. Lake Hayes Predator Free installed the first 36 traps in October 2018, and I have records for the Southern Crested Grebe counts from April 2019.
The overall trend of stoats being caught is decreasing, while ferrets have increased very slightly over time. Interestingly, the rat catches appear to be increasing, this may be partly due to increase in traps, or trap servicing/ more regular rebaiting. It is hard to assess this due to some members of Lake Hayes Predator Free not using the TrapNZ app correctly to input records.
As we know, the population of grebes fluctuates seasonally as they head further north for our winter. It does appear that they are returning in increasing numbers over summer, and that juveniles present are also increasing.
Fig 1. Lake Hayes monthly catches of mustelids since trapping began in Nov 2018 through to present.
Fig 2. Lake Hayes monthly catches of rats since trapping began in Nov 2018 through to present.
Fig 3. Southern Crested Grebe counts at Lake Hayes from April 2019 till present.
Fig 4. Juvenile Southern Crested Grebe counts at Lake Hayes from April 2019 till present.
Fig 5. Increase in number of traps around Lake Hayes from Nov 2018 to present.
The Lake Hayes predator free group do an amazing job. This data shows that trapping reduces the number of stoats, but rats catches are increasing, possibly due to an increase in traps and trap checks.
However, one thing is certain – since 2019 Grebe numbers have increased each year – what a fantastic outcome.
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