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The heaviest beech forest seedfall in more than a decade is predicted this year. It is expected the increased seedfall will lead to an explosion in the numbers of rats, mice and stoats, who will turn to our native birds for food once the seeds disappear.

Predator plague cycle

Beech trees generally seed every four to five years but weather conditions over the last two summers—a cool summer followed by a warm one—appear to have triggered a bumper seed or “beech mast” event. Intense and widespread flowering was witnessed throughout North and South Island beech forests during spring and early summer, prompting the need for urgent action.

Past experience has shown that when a beech mast occurs, it leads to a dramatic rise in mice and rat populations, who feast on the plentiful seed all winter. To give you an idea of how quickly they can multiply, a single female rat can potentially produce 10 offspring every eight weeks—that’s a lot of rats!

An explosion in rodent numbers leads to a sharp rise in the number of stoats, which also pose a lethal threat to many species.

Rat eating Fantail chicks at nest. Photo © David Mudge. DOC use only.

Rat eating fantail chicks at nest

In spring, when the seed runs out, germinates and rots, these predators will then prey on native birds and their eggs, as well as other critically endangered critters such as native bats and snails.

This will put some of our most threatened species at risk of extinction including:

kākāriki karaka/orange-fronted parakeet
pekapeka/short-tailed bat
whio/blue duck
Powelliphanta snails

Kea and tākahe are also at risk of being preyed on by stoats.

Yellowhead/mōhua. Photo © Michael Eckstaedt. DOC use only.


Landcare Research estimates that 25 million native birds die through predation every year in New Zealand and the beech mast is expected to make the situation much worse. For example, there are only 200–400 wild orange-fronted parakeet left and during the beech mast that occurred in 2000, 85% of the southern population was wiped out due to the rat plague.

85% of the southern population of orange-fronted parakeets were wiped out

85% of the southern population of orange-fronted parakeets were wiped out during the beech mast that occurred in 2000

DOC staff will monitor the amount of seed produced this summer and seedfall in the autumn. Rat tracking will also take place in February and May.

DOC scientist Graeme Elliott says, “So far we’ve only been able to get a visual idea of the issue. We’ve seen lots of flowering during the spring, which caused huge clouds of pollen above the forests.

“The seeds are developing at the moment but in February we’ll be able to start counting them to get a better idea of the scale of the mast. We do this by shooting down branches at the top of the tree, where they’re exposed to the sun and produce the most seeds.

“The best indicator will be the rat tracking. If the numbers dramatically increase or are already high in February, we’ll know we’ve got a big problem to deal with.”

Last night the Minster of Conservation, Dr Nick Smith, announced DOC’s plans to respond and launched our largest-ever species protection programme called ‘Battle for our Birds’. We’ll talk about this in more detail over the coming weeks. For now, you can learn more about it on the DOC website:

10 year old Jamie Hamilton is a Year 6 student at Glenorchy School, she often goes out trapping with her dad, a DOC trapping volunteer. She writes about a recent trip to Lake Sylvan.

At different times of the year my dad and I go trapping at Lake Sylvan.

Jamie heading out to check the traps

Jamie heading out to check the traps

The reason we go is so that DOC can monitor how many stoats and rats there are and to save our native birds. My dad and I do 34 traps and if you walk a little further past this trap line you will end up at the Rockburn Hut.

At the start of the walk there is a little sign and it shows all the markers that are shown on the track. The two that that we look for are the orange and blue markers, the orange are track markers and the blue ones show where the traps are.

Jamie with her dad.

Jamie with her dad

Sometimes dad and I have to leave really early so we can get back at a reasonable time. Once me and dad left at 8:00 am and got back at 5:30 pm. On that trip we got four stoats and one rat. One of the stoats was a baby and one was a white one, there wasn’t much left of them though. The white stoat is a normal stoat but its coat colour just changes white in the winter.

On the track we often see robins and rifleman and hear the beautiful song that the birds make.

A robin sitting on a trap at Lake Sylvan.

A robin sitting on a trap

I love checking the trap lines for DOC, I know I am helping to protect our native birds and I get to spend a day with my dad doing something we both enjoy.

Jamie sitting on rocks by Lake Sylvan.

Jamie sitting on rocks by Lake Sylvan

By Jane Dobson, Wellington-Hawkes Bay Conservancy

Fresh to the Wellington-Hawkes Bay Conservancy, I heard about the Oroua Blue Duck Protection Project in the Ruahines and an inspired volunteer team led by Janet Wilson. Needing to know more I contacted Janet and invited myself along on the January trap line check and rebait.

Oroua volunteers getting ready to head off.

Oroua volunteers with coordinator extraordinaire Janet Wilson: Jen James, Janet, myself, Henry Milne and Thierry Stokkermans

Janet arranged to meet us all at the Oroua River car park with equipment, advice and a refresh on DOC 200 traps. As beacons, maps, eggs and rabbit bait were split between packs, Janet told us about the previous weeks training where a man ‘just blanked’ and let his free hand slip and set off a trap. “That’s never happened before, he was lucky to get away with grazed knuckles. “Have fun and look after each other up there,” Janet looked at me. Apparently matching people with similar fitness levels is one of her many challenges.

Jen the Crossfit trainer, Henry the anaesthetist, and team leader/ mechanical engineer Thierry set off with me in tow. We planned to get to Iron Gate, split into teams to reach the Ngamoku Ridge tops and Triangle Hut, return to Iron Gate, then walk out the river line on Sunday. I reassured myself that I was fitter than I looked – for ‘a lady from the Wellington office.’ They’d been warned.

Olearia colensoi, leatherwood, below the Ngamoko tops

Olearia colensoi, leatherwood, below the Ngamoko tops.

Jen and I headed up the ridge. The thought of an evening swim in the Oroua’s emerald pools propelled us from trap to trap. Before long we had an efficient leapfrog system. The beech trees, lime green crown ferns, glorious leatherwood and tussock covered tops made up for any squeamish moments with the stoat and rat carcasses. I even imagined rabbit ‘jerkey’ could be tempting if you were in a tight spot.

Thierry and Henry walked upriver spotting several trout AND a whio/blue duck perched on top of a DOC 200 trap in the river, with three young ducks nearby. Was this cheeky whio mocking the stoats from its macabre pedestal, or alerting Henry and Thierry to the missing trap.

The girls didn’t see any whio but were rewarded nonetheless with Guiness at dinner (fantastic leadership Thierry) and choice bombs on Sunday. The low river, blue sky and cool and clear  river made for a stunning walk out.

Total count: 13 stoats, 13 rats. 

January 2013, Team Oroua in action.

January 2013, Team Oroua in action

Meanwhile, Janet spent her Sunday checking the self-resetting traps up the Tunupo Stream, a tributary of the Oroua. In May 2012 volunteers helped install 37 of these new A24 traps made by NZ company Good Nature. They were bought with funding from the He Tini Trust and Horizons Regional Council. These traps don’t need to be checked as regularly as DOC 200’s, but need re-gassing every six months or so. A down side is there is no clear pest count – the dead critter tends to breakdown or disappear from under the trap.

Jen James baiting for high-altitude stoats.

Jen James baiting for high-altitude stoats

Due to Janet’s nightly phone calls, training trips, constant advocacy and more, the project’s volunteer base is ‘committed and developing.’ Enthusiastic people are needed to prevent the situation the Manawatu Deerstalkers found themselves facing in 2011 with the same few people doing all the work. The coordination takes ‘AGES,’ Janet told me. ‘The Palmerston North tramping club is a great help, Manawatu Deerstalkers still help, the DOC newsletter Keep Tracking On advertises for volunteers. I also put notices in the huts with tear off numbers. We’ve got a committed but developing volunteer base. I’m investing in the training weekends, hoping it will pay off.’

Whio enjoying the view from a washed out trap.

Whio enjoying the view from a washed out trap

Janet won the 2012 Individual Manawatū Rangitīkei area Conservation Award, which recognised her on-going commitment to protecting wildlife through stoat control in the Te Potae o Awarua project, the Manawatu Gorge, and for rescuing the Oroua Blue Duck Protection Project from folding in 2011.

You’re an inspiration Janet Wilson – volunteer coordinator extraordinaire.

Click here to find out how to get involved.

Evidence of an ‘A24’ trap kill up Tunupo Stream.

Evidence of an ‘A24’ trap kill up Tunupo Stream