Leigh Harbour Valley Society

Leigh Harbour Valley Society (LHVS), was formed in 2009, and has been pivotal in transforming over 190 hectares of Cape Rodney’s landscape. Weed and animal pest control are central to LHVS’s success, with community involvement playing a key role as local landowners actively participate in restoration efforts.

Using over 380 traps, regular monitoring, and pulse baiting, LHVS has seen a marked increase in native birdlife, including korimako and kaka. We caught up with LHVS to learn more about the group’s strategies for tackling invasive weeds like climbing asparagus and tradescantia, as well as their predator control measures.

Kathryn Erikson from Leigh Harbour Valley Society worked with Virginia Moreno from The Forest Bridge Trust’s Ecology Team this year and took time to give us an insight into LHVS mahi and highlight the dedication to preserving Cape Rodney’s natural heritage, showcasing the power of community-driven conservation initiatives.

What geographical area does LHVS cover?

Leigh Harbour Valley Society covers several forest bush remnants and private properties on Cape Rodney, including regenerating bush. We have also carried out restoration work on Scenic Reserve land. The area of control has extended over the years to include properties on the north/eastern border of Cape Rodney and now covers over 190ha. The area includes regenerating coastal forest and a healthy stand of kauri.

LHVS formed in 2009 and one of your first actions was to commission a forest restoration plan which highlighted a serious weed problem in the area. How did you address this problem?

Privet was everywhere. In the early days we paid our children to pull out privet seedlings (25 cents for the very small ones and 50 cents for the larger ones).

We certainly made a few mistakes along the way when we launched into a more serious pest plant control programme, including chain sawing large areas of privet, thereby opening light wells, and allowing more weeds to grow. We eventually resorted to the drill and kill method of control and only felled privet in areas where native plants were more established.

Tradescantia was a real problem in parts of the valley. We raked, rolled, and bagged this weed but within no time it had become re-established. We made the mistake of spraying large areas. Thanks to input from an experienced restoration volunteer, we eventually focused on hand control, thereby allowing native seedlings to become established.

Tradescantia beetles were introduced by one landowner, and we have recently noticed Tradescantia Yellow Leaf spot fungus. While Tradescantia still exists in parts of the valley and there is much work to do controlling this and other pest plants, we believe we are winning the battle. As the birdlife has increased, so have the number of native seedlings.

Can you tell us more about what’s involved in the monitoring and controlling of weeds, particularly those with a high ecological impact like Climbing Asparagus, Moth Plant, Kahili Ginger, and African Club Moss?

Most of our weed assessment is carried out by foot and observing weeds along the tracks which usually indicates a larger infestation nearby. Much of the terrain is steep which has made accessing these weeds challenging in certain areas, so we have had to employ abseilers to carry out some of this work. More recently we have used a drone to identify weed hotspots.

The worst areas of climbing asparagus were sprayed with diluted glycosphate. Contractors were employed to control weeds in some areas, particularly those of high conservation value, including a kauri forest at the top of one of the catchment areas. We have dug out vast amounts of Kahili ginger. African Club moss has been managed by hand and by spraying with cider vinegar which we have found to be particularly effective in the summer months when the ground is drier. We have positioned mulching bags along the tracks so weeds can be bagged after they’ve been removed. We’ve collected 1000’s of mothplant pods in areas surrounding the bush blocks and regularly remove seedlings before they turn into vines. We have also drilled and killed wilding pines. The larger areas of control are marked on Trap NZ and we revisit these sights at regular intervals to ensure our control methods have been successful.

The control of pest animals has been another focus for LHVS. How does the society currently trap mustelids and rats and what plans are in place to increase the focus in these areas?

We have over 380 traps in the bush blocks, including several AT220 self-setting traps on the steeper, less accessible areas. Our team of trappers check the majority of traps every 2-3 weeks. The AT220’s are checked every 3 months. We have been carrying out a pulse baiting programme for the past two years, using 1st generation toxins. We have several cameras and carry out regular monitoring using tracking tunnels. Recently, we ramped up our mustelid control programme by redeploying some of our DoC200’s and installing a lot of smaller stoat traps on farmland bordering the bush areas in an attempt to increase the halo of control.

How has The Forest Bridge Trust been able to assist you with maintenance of traps?

Forest Bridge Trust’s trapping experts have assisted us with servicing our DOC200’s and AT220’s, and by sharing trapping advice and teaching us how to download important trapping data. We are in regular contact with their Community Liaison and data support representatives.

How have you been able to involve and motivate landowners in the area to conduct regular pest animal and pest plant control on their properties?

Most of our success with bringing people on board has been by word of mouth and occasionally by meeting and chatting with landowners while we are out trapping or weeding. Our team of trappers and supporters communicate regularly via WhatsApp which has proved to be a perfect tool for relaying trapping information, as well as for updating and motivating landowners. We have also carried out volunteer work on neighbouring properties and the landowners have supported our efforts by making donations to the LHVS which allows us to continue our work. We have raised funds to remove wilding pine seedlings from the Leigh Coastal walkway. Several landowners agreed to fencing stock out of streams on their properties, which was funded by Auckland Council (previously Rodney District Council). We planted and maintained native trees inside the fenced areas, supported by Trees for Survival and others.

What changes have you seen to flora and fauna since pest and weed control measures have been in place?

There has been a marked increase in native birdlife, as evidenced by the number of native seedlings. Korimako and Miro Miro have been observed and videoed in the bush. There has been a huge increase in Kereru, and Kaka are present from dusk till dawn.

Leigh Harbour Valley Society recently worked with The Forest Bridge Trust’s ecologist Virgina Moreno on a Lizard (herpetological) monitoring evening; can you tell us more about what inspired this project.

The herpetological monitoring evening with Virginia Moreno was a great experience. It is amazing seeing the stream coming to life at night.

It was always our intention to restore the bush when we purchased our property in 1994. the land had previously been farmed and cattle were allowed to enter the native broadleaf forest areas. Prior to commencing the restoration project, we discovered several decapitated native birds and feral cats were observed in the area. We heard that Auckland Council and Department of Conservation provided grants for restoration work, and it was with their help that we initiated our pest animal and pest plant programme. We later joined forces with other landowners and neighbours and The Leigh Harbour Valley Society was formed.

Over the years, we have observed a noticeable increase in native birdlife and in the number of native seedlings. We learned that a herpetological study was the next step in assessing the overall health of the Forest. This was made possible by the experts from The Forest Bridge Trust.

What are your biggest challenges? How are you hoping to overcome these?

Weeds from surrounding areas continue to threaten our restoration efforts. It is all very well carrying out pest animal control but if the weed problem results in ecosystem collapse, then there will be nowhere for the native birds to nest. With our regular weed control programme, we believe we have reduced the impact of weeds across the landscape we are managing. However, reinvasion of weeds from beyond the control areas continues to be a challenge.

We have the ongoing challenge of attracting enthusiastic volunteers to assist with managing our trap and bait lines and helping us to progress with our weed control projects. However, we are fortunate to have several regular volunteers on our team who have a lot of expertise in biodiversity management. We also have the next generation of conservationists coming on board.

Cyclone Gabrielle damaged a lot of old, established trees and washed away parts of our tracks. Track maintenance is an ongoing requirement.

What is the long-term vision for the area and the society?

We still have a long way to go with this project. Our aim is to maintain our restoration efforts on the Cape Rodney peninsular and ultimately provide a sustainable sanctuary for native bird life, including birds not seen in the area for many years. It is hoped that landowners of adjoining properties who are not currently participating in the project will come on board so we can extend our area of control.

With the establishment of other restoration groups in the surrounding area, including Pest Free Leigh, Forest and Bird Coastal Care Group, Te Kohuroa Rewilding Initiative and other catchment focused groups, the future for native flora and fauna in the Leigh area looks rosy.

How can people get involved and help LHVS?

If anyone is interested in participating in one of our working bees, planting days or helping with our trap lines, they can contact us via our Facebook page or website. We always provide delicious food!