Trekking through thick native bush for hours with a heavy rucksack full of bait isn’t the most glamourous of jobs, but for Field Work Coordinator Derryn Jakobi and colleagues, it’s an incredibly important one to complete.

Every three months, Derryn and the team venture into the heart of the Waitākere Ranges to complete bait-lining work in the Ark in the Park, a conservation partnership between Forest & Bird and Auckland Council. Though the nature of this work might not be well publicised, it is incredibly important for the survival of so much of our native flora and fauna.

Bait-lining/lines may not be a term you’re aware of – and for Derryn who has been doing it for a while now, it’s still a tricky concept to sum up in a few words. 

“Bait-lining is used for predator/pest control in areas where native flora and fauna live. It helps keep pest numbers down so our native species can survive and hopefully thrive. We fill custom-made containers (often made from recycled milk bottles) with bait at different points on a transect or ‘line’ that spans a certain length through the Waitākeres. These are called bait stations.”

Despite the name, no physical lines are connecting these bait stations. Instead, bait stations are placed 50 metres apart along a line that can sometimes span 23 stations (1,150 metres in length!) and the team use flagging tape to keep on track – much like breadcrumbs in Hansel and Gretel! The bait lines run north to south and are 100 metres apart from each other to help maximize pest control across the Ark in the Park project. The area each bait line passes through seems relatively small alongside the entire Waitākere Ranges, but combined with the other 400 volunteers who also bait line within the area it covers a whopping 2270 hectares!

Bait-lining is used for predator/pest control in areas where native flora and fauna live. It helps keep pest numbers down so our native species can survive and hopefully thrive. We fill custom-made containers (often made from recycled milk bottles) with bait at different points on a transect or ‘line’ that spans a certain length through the Waitākeres. These are called bait stations.

Fieldwork Coordinator, Derryn Jakobi

The Waitākere Ranges is one of many beautiful parks in Aotearoa. However, unlike famous reserves such as Karori (Zealandia) and Maungatautari, the Waitākeres is without any predator-proof boundaries or fences. This means that the native flora and fauna that call this place home are at great risk of predation, or even extermination, due to the sheer numbers of pests in the forest. The most common pest predators are rats, stoats and possums, and pig activity is also rife.

Within the Ark in the Park boundaries alone, the volunteers and wildlife experts who complete this intensive bait-lining are working hard to protect threatened native bird species such as the:

  • North Island kōkako
  • Toutouwai (North Island robin)
  • Korimako (bellbird)
  • Koekoeā (long-tailed cuckoo)
  • Miromiro (North Island tomtit)
  • Pōpokatea (whitehead)

However, as Derryn explains, it’s also important to focus on the native flora that spans this extensive footprint. 

“The vegetation out there sometimes takes a backseat to the animal life that inhabits the area. While it isn’t as cute and cuddly, it’s still incredibly impressive and crucially, provides habitat and resources for the animals which call the Waitākeres home”.

From ancient kauri trees to lush ferns and delicate orchids, Ark in the Park’s rich ecosystem supports hundreds of different plant species. And it’s the work volunteers like Derryn and her zoo colleagues do that help this forest to thrive and once again support healthy populations of native animals and plants. 

So, what does a typical day of bait-lining look like? “In a nutshell, green; very green!”

Auckland Zoo is in charge of ten bait lines within Ark in the Park, and typically Derryn and a team of willing zoo keepers and other staff, head out to complete them every three or four months, depending on bait uptake. “We just wait for the ‘bat signal’ from the Ark in the Park Volunteer Coordinator and then we hit the park!”

Last month was the last time Derryn and team received said signal and as usual, they drove out to the Waitākere Ranges early in the morning to get the best start possible (and avoid Auckland traffic!). Upon reaching the park, the team strapped on their hefty backpacks full of bait and began the 45-minute hike through dense bush to the six bait lines. As the bush is so overgrown - Derryn is 6 foot/1.8m in height, and she describes how she was sometimes in over her head (literally) being dwarfed by kiekie and cutty grass - and the bait lines span a considerable length so the team split up into smaller groups and divvied up the six lines between them.

When the volunteers check a bait station, they’re not looking for pests. Instead, it’s signs that they’ve been in the area and engaged with the bait at the station. The bait is contained within small bags that are secured by plastic ties of different colours. These colours represent different months (or bait round) and help volunteers keep track of when the bait was placed.

“It’s just like a series. If the bait hasn’t been touched, you might leave it in the bait station but the coloured tie lets you know how long it’s been there. So, for example, if blue ties represented October, in January, you’d look at replacing the bait with a fresh bag or trying a different type of bait to see if that one works better.”

While working on bait lines, volunteers record information as they go, known as bait uptake. They’ll record whether the bait is all gone, half gone, or all there which influences the next round of baiting. Ark in the Park then collects all findings and collates it into a map of the area which shows bait uptake from the lines within its border – as you can see on the right.

At the moment, the majority of the Waitākere Ranges is closed to help minimise the spread of kauri dieback disease. Ark in the Park bait line volunteers can continue their work but must take special measures to avoid spreading the disease. Derryn and team enter the Ark with clean boots and throughout the day, spray and scrub them to avoid harming the kauri trees along their bait lines. When it’s time to go home, they clean all their gear at the Ark office and change into a clean pair of shoes to avoid any soil from the Waitākeres leaving with them. These measures are extremely important in maintaining this stunning section of the North Island and along with bait-lining, helps protect the forest and all those that call it home. 

Auckland Zoo has been looking after these six bait lines for almost 10 years. Derryn estimates that this equates to more than 800 hours and more than 20 staff across our different departments, which is an incredible effort. On top of these six bait lines, the Auckland Zoo Education team manages a further four bait lines, which they recently completed despite a particularly relentless rainstorm! 

The bait lines we maintain are also utilised by our bird team when they visit the Ark to complete the annual census of the reintroduced kōkako – happening right now in mid-winter! Derryn recently joined some of our bird keepers on a visit to the Ark and saw just how the bait line work she is a part of benefit other facets of wildlife conservation.

“Bait lines are fundamental to the success of the kōkako census project. Not only does it help to keep predator numbers down, but the bait lines also give us an existing survey grid to work from, the pink flagging tape helps us safely navigate and the people that have walked the bait lines before us have forged the path through the dense vegetation which saves us a lot of time and energy getting from one census site to the next. We’re very grateful and I think this speaks to the very nature of conservation work i.e. that it takes a lot of people to pitch in, in different ways to bring about positive outcomes for our taonga species.”

When asked if she believes bait-lining is working, Derryn explains that it is the best thing they can do for an area with no predator-proof fencing. 

“The fact that the forest has plenty of undergrowth shows signs that it’s able to regenerate. There have also been several translocations of other birds including the toutouwai (North Island robin) and pōpokatea (whitehead) to the Ark to help restore the bird species assemblage. As such, the Department of Conservation and other wildlife authorities believe that predator levels are at a level where it’s safe for translocations to take place.” 

Currently, Ark in the Park has 400 active volunteers who contribute to the upkeep and protection of the area in different ways. Along with the bait-lining work that Derryn and many others undertake, the Ark is also responsible for a range of monitoring, trapping and research work. The organisation relies on its volunteers to continue this vital work and is always on the lookout for conservation enthusiasts to join the team. Find out more about what it takes to make a difference in this piece of paradise here

It’s fantastic to hear about how the wider Auckland Zoo whānau assists with the important and intensive bait-lining work and comes together to protect and preserve the wonderful nature that surrounds our central city hub. So much so, that perhaps next time, I’ll be ready to answer the ‘bat call’ with Derryn and team!