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.