Plenty poses forest pest plague
Masting in our beech forests, which produces a bounty that once sustained our native species, now threatens their existence.
Conservationists are bracing themselves for exploding populations of rats and stoats this year.
Responsible for this menace is an exceptionally plentiful supply of seeds in New Zealand’s beech forests during the autumn.
In a process known as ‘‘masting’’, some 50 million beech seeds will fall per hectare. For each hectare that’s about 250 kilograms of seeds.
At one time, the superabundant seed would have nourished kakapo and other native species, encouraging them to breed.
But with those species on the brink of extinction, it’s rats and mice that feast on the bounty instead, leading to dramatic population rises.
A female rat reaches sexual maturity at five weeks of age and can produce ten offspring every eight weeks—that’s a lot of rats!
All these rats and mice mean a feast for stoats. Their numbers explode as well.
Next spring, the beech seed will rot or germinate, making it useless as a food source. Threatened with famine, predators will turn their attention to bird eggs, nestlings, native bats and snails.
Among the species put at risk are kiwi, ta¯kahe, ka¯ka¯, kea, whio (blue duck), mo¯hua (yellowhead), ka¯ka¯riki (native parakeet) and pekapeka (native bats).
Stoats, by far our worst predator, kill an average of 40 North Island brown kiwi chicks a day, equivalent to 60 per cent of the annual brood.
Making the situation still more critical, 2015 will be the second beech mast year in a row.
In response to the 2014 mast year the Department of Conservation (DOC) launched its ‘‘Battle for the Birds’’, which saw
Stoats, by far our worst predator, kill an average of 40 North Island brown kiwi chicks a day.
rat numbers crashing at most sites and averted a plague of stoats.
However, Forest & Bird is concerned that funding for a second ‘‘battle’’ will not be available this year.
Kevin Hackwell, Forest & Bird group manager for campaigns and advocacy, will be talking about the threat posed to our native species by these two successive beech mast years at the monthly Forest & Bird meeting on Tuesday, April 12.
All are welcome to hear Kevin’s talk in City Library at 7.30pm.
Rats feeding on eggs in the nest of a song thrush. Rats are skilled tree climbers and do not discriminate between native and introduced birds.