Rats, possums and Hamilton’s native biodiversity

All too often the focus of predator control is on protecting our native birds and often a single bird species. This results in a management plan that is designed around the birds nesting period. A common practice is pulsing where rat populations are knocked down using baits in the lead up to and during nesting, after which control is withheld until the next season. This allows the rat population to build up again. In an uncontrolled area a single pair of rats can be responsible for producing up to 2000 rats in a season when considering the multiplying effect of their off spring. While there is a place for this strategy it has no place in Hamilton City where the whole native ecosystem must be targeted for protection. An effective pest control plan against rats and possums needs to be put in place city wide that embraces baits for rats in natural areas and leave rat traps for the urban back yards. The accompanying photo of a display at the Auckland War Museum is a good example of where our invertebrate fauna has all too often been neglected and has been decimated by rats into extinction. Creepy crawlies have no public profile but are still an important part of our ecosystem and need year round protection. In the July 30th Listener Veronika Meduna’s review of the book Rewilding the Sea by Charles Clover sums it up well “Clover acknowledges the work of Bill Ballantine, the late ocean-conservation pioneer who fought to create the world’s first no-take marine reserve at Leigh, north of Auckland, and was a strong proponent of ecosystem thinking - as opposed to many conservation efforts on land, which focus on fragmented species rather than habitats”. Click on photo to enlarge.

Admiral butterfly breeding programme underway

For a number of years, we have been trialling a breeding programme for yellow and red admiral butterflies off site. We have secured funding from the local Forest and Bird administered Valder Funding Grant to purchase a biomesh covered 4.5 metre long tunnel house. This is being installed at our depot off Grenache Place in Rototuna. Both the yellow and red species are in decline. The red particularly so and it is regionally extinct in some areas of New Zealand. This is primarily because of loss of host plants (habitat loss) and predation by introduced wasps (there are three species). The largest of New Zealand’s endemic nettles, Urtica ferox or ongaonga, is a woody shrub that can grow up to 5 metres in height and is favoured by the red and yellow admiral for egg laying. Within the safety of this nettle bush, admiral larvae find the perfect home to grow, with plentiful food and some protective cover from predators. Nettle will be grown in large 12Lt plastic planter bags inside the tunnel house and pruned to contain their size, along with some nettle being planted outside to attract any butterflies in the area. From experience this would be predominately yellow admirals. Caterpillars will be gathered from the outside plants and relocated into the tunnel house, where they will be able to finish their life cycle protected from wasps. Once hatched they will be released to the outside. Another possibility could be to capture a female when seeing it laying on the outside nettles and release it into the tunnel house to lay in there. We are growing extra nettle seedlings with the hope that some of the people that live on the gully edge may have a suitable place to develop a nettle grove so that we can grow a sustainable population in Mangaiti.

Success breeds success

There has been a lot going on in Mangaiti Gully of late. The new track from Keswick up to Gordonton Road, the Jobs for Nature team working restoring the gully from Keswick to Hukanui Road and the opening up and upgrading of the tracks through the Volunteers area Keswick to Sexton Road / Haswell place. This has all attracted a lot of attention. While it is flattering to get this attention, it does take time and it distracts from getting on with our core business. There was a major feature in the Saturdays paper by a local Waikato Times journalist, Richard Walker, on Hamilton Gullies. Mangaiti was referenced a number of times in this article. There was a very successful visit by Kiri Allan during her time as Conservation Minister. This was organised by our regional DOC office and involved a number of other invited guests including our mayor, Paula Southgate and media. TV1 visited Mangaiti to get sound bites and visuals for a documentary they are working on. After twelve years of our Trust quietly working away restoring the gully to suddenly get all this activity and attention tends to be a bit overwhelming, but let’s not knock it. Mangaiti is on the cusp of being transformed into a major public asset for the city and for an upgrade of the ecological habitat for our indigenous biodiversity. Photo1: Kiri Allan visit Photo2: TV1 recording sound and visual bites

Major upgrade of the tracks through the volunteer area

Once our tracks were opened up through to Keswick Place there has been a noticeable increase in foot traffic. This has led to our Trust evaluating the condition of the tracks and bridges in our section, which were originally put in to give our volunteers access to areas to restore. We are not going to change the design, which are not official Council spec, hence the gate they erected at the Keswick end. Our focus is to make the tracks more robust by doing maintenance to the boardwalks and timber track sides, then filling the tracks with a good depth of shingle. The wet areas are, and always will be challenging. We are having issues with people bringing bikes through our tracks, despite signs indicating that bikes are not allowed. We are not anti-bikes it is just that the tracks and boardwalks are not suitable for bikes. Bikes cut up our tracks, particularly where they go through bog areas. On boardwalks the bikes end up off the boards and cut up the mud at the side. This all adds work for our volunteers. We are designing signs to be erected at the four entry points, with a colour coded map of the tracks which lines up with coloured pegs along each of the tracks. This will help resolve people wandering aimlessly around wondering where they are. Photo1: cycle damage Photo2: Boardwalk realigned and cycle damage repaired. Photo3: No cycling sign, yet still they come!

Developing a Rongoā Rākau demonstration site

So, what is Rongoā Rākau? The best way to explain this is to translate Māori to English. Rongoā is medicine and Rākau is grove or tree so basically Rongoā Rākau is the Māori use of native plants as herbal medicine. This project is being led by a member of the Jobs for Nature team. A site has been selected close to the Hukanui Road entrance where the ground is free draining (a rarity in Mangaiti Gully). It is still in the early stages of development. The track has been cleared but not yet formed and some planting done. The end result will be primarily a demonstration site with selected native plants being planted along an all-weather track with educational signs for each species. The photo is an example of possible sign layout.

The Lazarus effect (back from the dead)

In the 2017 summer edition of Forest and Bird, Ann Graeme wrote an article on what she called the “Lazarus Effect”. The article is based around how the New Zealand flora and fauna comes back to life where there is effective pest control. She says, “Yes, it is worth it, this work, month after month, by hundreds of local volunteers in dozens of forest restoration projects. As the pests are beaten back, seeds sprout, shoots appear, and birds, lizards and invertebrates can emerge from the shadows”. After six years of effective rat and possum control by volunteers in Mangaiti Gully we are indeed seeing the Lazarus effect. Frequent reports come to our Trust of unexpected new sightings of our indigenous fauna showing itself. The latest was a juvenile cuckoo fledging being feed by its adopted grey warbler parents. The attached video clip, taken by Tony Grey, catches it just after the fledging was fed. And stick insects are suddenly appearing and anyone that lives on the gully will know the story about the increased in the tui population. Photo: Stick insect - Murray Holt.

Biological control of tradescantia (wandering willy)

In December 2021 a combined team from WRC, Jobs for Nature and Mangaiti Gully Restoration Trust released the tradescantia virus into a heavily tradescantia infested area of the gully at the back of Montrose Cres, Huntington. The photo shows the damage the virus does to the leaves. This was taken at the Waingaro site. The virus was released at Waingaro four years ago and in places has wiped out the tradescantia. Hopefully we can achieve the same result. Just to make sure we cause maximum damage, the team also released the 3 types of tradescantia beetles into the same area. Two beetles attack the leaves and the other the stems. On recent inspection things are progressing well with a particularly good uptake and spread of the virus and the beetle that attacked the leaf edge. Photo 1: Tradescantia beetles being introduced. Photo 2:Virus infected tradescantia

Kauri planting struggling to get established

Kauri are not a species that are generally considered to have historically grown in Hamilton gullies. We therefore do not routinely include kauri on our planting lists. However, there are a considerable number on the gully tops that residents have planted. With kauri die back devastating the northern kauri it is time to rethink the policy as regards planting kauri. An isolated grove as a potential future seed source may well be of value. The southern gully slope below Sovereign Isles was selected as a suitable site and 20 Kauri were planted in August 2021. This site had several advantages. 1. It has a good vista from the existing board walk below the Keswick entrance. 2. It is a well-drained site that suits kauri 3. It is isolated from foot traffic therefore would have a very low possibility of contracting the disease at some future date (the disease is spread through soil movement) 4. Being on the south side of Sovereign Isles future growth would not shade any dwellings at the top of the gully. Ten months on and the summer drought killed off 15 of the young plants. These are being replanted this winter. Photo: Dead Kauri in a Northland forest- Rex Bushell

Epiphyte Collospermun hastatum 2012 -2022

We have a good range of epiphytes growing in the shade house (see photo) but have been uneasy about introducing them into the wild. The conditions they normally grow in tends to be a lot damper than Mangaiti gully. This year we came across one that we had attached to a double tree fern trunk back in 2012. The location was out of the way and quite hard to get to. This year we made point of checking it out and to our surprise it has done very well. See the photos. Epiphytes are an important part of the biodiversity of the flora mix and it would be good to get them established in the gully. Photos: 2012 , 2022 and in shade house - Rex Bushell

Scouts planting

What a day, what a lovely day. A delight to see young ones having great fun outdoors, getting their hands, and some feet, in the mud planting flax on the wet gully floor. While one of them accused us of exploiting child labour (do they know such things at this age?) they all really did enjoy themselves, as did the parents. We have very limited opportunity to get groups of children in for planting because of the terrain in our gully. It is usually too wet or too steep or the plant type makes it more difficult. This was just flax. Hard to kill and they just had to get it into the soft, muddy ground. Nice and simple. This area is mainly flax with a few cabbage trees. The flax is planted close together to support each other. There are no canopy trees planted. The plan is that, in the future, you can walk through the kahikatea dominant forest then come out into a clearing covered in flax. Flax like sun so, with no trees, they should thrive. Drone photo: Child labour hard at work!- David Roper

Natural flora regeneration is underway

After twelve years of restoration work in the gully it is evident that the natural cycle has started with self-seeding of numerous native plants. Some, like a pukatea, are seeding from a tree planted well before we started but has only recently come into full maturity. There are numerous kahikatea, totara, wine berry, cabbage trees (by the thousand), mapou, rewarewa, tree fuchsia, kawakawa, hebe stricta, pate, swamp coprosma, manuka and kanuka all off doing their own thing. All we have to do now is keep the weeds down to let them thrive. Photo: A self sown pukatea seedling - Rex Bushell

Serious engineering work going into track building

For those that live on the gully, it will not be news to you that there has been some serious engineering work going into building a track up through Zone 3 (the section from Keswick to Gordonton Road) along with weed clearing and planting. This has been made possible through a $2.5 million funding package that Hamilton City Council secured through Crown Infrastructure Projects – Water, stimulus plan. The track is due to have it’s formal opening in July. The design and build are a credit to all involved. It opens the final stage of the gully for clearing and planting into native flora and sets in place the whole thirty hectares of Mangaiti Gully to become a valuable natural asset for the city. Video: The helicopter taking in timber for the boardwalk sections of the track. The most cost effective way of getting it in - Tony Grey