Rats and mice are in huge numbers
Beech mast leads to rat & mouse population explosion
The Arthur's Pass Wildlife Trust maintains 383 stoat traps in the Bealey Valley. Since the beginning of winter they have been running hot with rats with 207 captures, only 11 were captured in the same period last year. The Beech mast (full seeding) of 2018/19 is driving a marked increase in rat numbers after residual populations survived the mild winter. Further to this mice are now exploding in population as they hoover up the beech seed. Rats eat mice, but Stoats eat mice & rats, so the apex predator of the forest will also see a huge increase in population.The problem lies in that it is extremely difficult to capture stoats in traps when so much other more attractive food is in plentiful supply. Come next Autumn, the mice numbers will subside naturally into winter, leaving a ravenous load of predators; the stoats will continue to clean up the rat population, but will then turn their attention to the native bird-life in Spring when their breeding season gets underway. All ground nesting birds and their eggs (Kea, Kiwi, Whio, Weka) are literal sitting ducks for the stoats, and tree nestors won't fair much better.
With climate change the beech forest is masting much more frequent than its normal 3-5 year cycle, as it gets stressed by drought and other weather related events. Hopefully we avoid another mast in the 2019/20 season.