Beech trees differ from most plants in producing abundant seeds only every three or four years in what’s called a ‘mast’, a truly amazing event with some 50 million seeds falling per hectare of forest. Once a beech mast occurs the abundance of seeds for predators to eat means their numbers swell exponentially; when that food dies out, the predators turn to native birds as their food source.
DOC undertakes large-scale operations to reduce the impacts of these plagues, and community groups like Forest & Bird help by running predator trapping lines in sensitive areas. This season, the trapping programme has been (and is continuing to be) a stunning success in the Makarora valley — but only due to the tireless volunteers who trek these lines in their spare time to empty the traps and relay the bait.
They found more rats in the past month than in the entire past year. In the whole of 2017-2018, Forest & Bird trapping removed seven stoats, 197 rats, and 237 mice from the Makarora environment. Yet, in one month alone for October 2019, the tally was five stoats, 205 rats and 45 mice.
Despite the success of the season people from Forest & Bird were far from being completely satisfied, “Although the Forest & Bird group have a couple of dozen volunteers clearing our seven traplines twice a month, we can cover only a tiny part of the forest on foot. To make a real difference, aerial spreading of baits is the only tool that is currently available,” said Jane Young.
It simply is not feasible, even for professional trappers, let alone the volunteers, to cover the area required on foot. “So we are pleased that an aerial 1080 operation has taken place. We are hopeful that the rat numbers will be well down next month, and that the stoat plague that follows the rat plague will not be so severe as a result,” reported Young.
Stoats have started appearing in the traps, but commonly the peak numbers will not appear until summer. The aerial operation seems to have been providential, since “With predator numbers this high, even all of our volunteer efforts would probably not be enough to prevent local extinction of some bird species,” admitted Young.
Following the 1080 drop, many volunteers reported that the forests are anything but silent. “The track workers on the new Blue Pools track reckoned the huge numbers of mice they were seeing had gone two days after the 1080,” said Young. Fifteen rats, seven mice and two stoats were caught on one trap line, but following the aerial drop, a fortnight later the traps proffered only four rats and two mice.
The only ones happier with the results than the volunteers were the birds. Many volunteers, who are also seasoned bird watchers, identified chaffinch, bellbird, grey warbler, kakariki, fantail, kereru, tomtit, rifleman, blackbird, shining cuckoo chaffinch, shelduck (paradise duck), bellbird, brown creeper, grey warbler, silvereye, kakariki, fantail, welcome swallow, kereru, tomtit and tui. The forests were in full song and “anything but silent” according to multiple first-hand accounts.