Project Tongariro and the Department of Conservation (DOC)have been working together on to protect the native biodiversity of Mt Pihanga and Lake Rotopounamu since 2003 by adopting a sustained integrated management approach. The area is a part of Tongariro National Park and the World Heritage Site. The project is to be community-focused with integrated pest management at its core.  You can ‘adopt a hectare’ and become part of the most significant forest restoration project in the Taupo catchment.

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Project Tongariro is pleased to confirm that several grant applications have recently been successful, to the tune of $40,000, which secures the 2011/2012 summer forest restoration programme at Rotopounamu. The grants are from Huckleberry’s Sports and Charitable Society ($5,000) , Sir John Logan Campbell Residuary Estate ($20,000), and W N Pharazyn Trust ($15,000).

Karen Williams, Project Tongariro president says the recent grants are a strong show of support for what has become the most significant forest restoration project in the district.  “The rats and stoats have been hit hard and many of the birds are making a comeback. Rifleman and the North Island robin are often seen and the larger birds like kaka, kereru and falcon have returned.”

In addition, the Adopt a Hectare initiative continues to be popular with several more adoptions since our last newsletter.  To become a kaitiaki (guardian) of a hectare and help restore the dawn chorus, hop online to view the map and to select your hectare. www.tongariro.org.nz/adoptahectare

Report from Ian McNickle, Ranger Biodiversity, DOC

Recent tracking tunnels results look great, only picking up one mouse and two rats. Kevin was the only one to pick up any rodents (all on line 1) which is always subject to re-invasion being so close to the boundary of the bait station network. One possum got into a tunnel up on line 13 and weta tracking has tripled since the last round.

December 2011 results are rats at 3% and mice at 1%.  The following graph shows the positive trend track tunnel index results from Aug 09 to Dec 11.

In February 2011, Project Tongariro intern students and DOC biodiversity rangers spent 2 weeks monitoring the birds up at Rotopounamu. The method used was 5 minute bird counts where you sit in allocated positions and listen and watch the birds in the surrounding area for 5 minutes. Anything bird seen or heard is recorded. 476 counts were completed and the results of 13 main bird species were analysed and compared 2009/2010 results.

Figure 1: Number of counts per 5 minute bird count for the 13 species at Rotopounamu

Some remarkable results came from this years monitoring. All species increased in numbers apart from Falcon and Silvereye. Kaka, Robin, Fantail, Kakariki, Whitehead, Long Tailed Cuckoo, Kereru, Grey Warbler and Honeyeaters (Bellbird and Tui) increased in numbers significantly. Although Silvereye appeared to decline they have always been recognised as bad indicator species due to their flocking behaviour. It is difficult to estimate numbers when they are flocking and people often underestimate the numbers they see.

Because monitoring was undertaken post breeding season, these results show that the birds had a very successful breeding season which at this stage we can associate with low rat numbers from October to February.

The increase of NI Robin, Fantail, Whitehead, Grey Warbler, Bellbird and Tui can all be associated with rodent control at Rotopounamu. For these birds, rats have the greatest impact through direct predation on nests and competition for food including fruit, seeds and invervebrates. The young of these species will have been calling throughout the month of February and would have been picked up in the bird call monitoring. Fantail, Bellbird and Tui in particular have had a hugely successful season.

An interesting observation is that Kaka is one of the species that has significantly increased in numbers from last season. It is well know that kaka are stoat sensitive species however research has also shown that there is considerable overlap between the preferred foods of kaka and possum (O'Donnell & Dilks 1986) and that possums remove some of the high energy food sources that Kaka probably require for breeding (Wilson 1984). Rats are not considered as much a competitor because they generally don’t feed in the canopy where kaka food is located. However rats have been confirmed as predators of kaka nests. On Kapiti Island in 1988, nearly 23% of nests were preyed upon by Norway rats. Mainly chicks were eaten. There is some evidence that kiore prey on kaka chicks on Little barrier Island (Lloyd, 1991). Ship rats that are much more arboreal than other rats and are widespread and common on the mainland could be significant predators (O’Donnell & Rasch, 1991). As a result although stoats are not managed at Rotopounamu, managing rats and possums might have some benefit to kaka and could explain the significant increase in kaka numbers from last year. It is also important to note that although mustelids are not controlled at Rotopounamu (apart from the 50 traps around the lake), tracking tunnels were run in December 2010 to monitor mustelid numbers and no mustelids were tracked indicating there is a low number of mustelids at Rotopounamu.

Kereru are another species that have done significantly well this season. The rodent control would have definitely improved breeding success and therefore population increase of the Kereru as rats and possums (of which were both controlled to low numbers) are the biggest threat to the nesting stage of the Kereru (Mander et al, 1998). It is likely that this year was a good fruiting year because a large proportion of Kereru will attempt to breed in good fruiting years whereas if the fruiting is bad very few kereru will try and breed (Mander et al, 1998). Similarly however, the increase in Kereru this year could have been a result of a good fruiting season last year. It is likely however that the low rat and possum numbers at Rotopounamu did increase the survival rates of any young Kereru that were breed this year.

In conclusion, most bird species have done very well this breeding season at Rotopounamu which is very likely to be due to the control of rats and possums to low numbers within the 540ha protection block. It is important to recognise that there is a limitation in this project being that there is no control site to compare how the birds would have done without rodent and possum control i.e bird count monitoring undertaken outside the protected area in February.

Only data since 2009-2010 has been used in this analysis. This is because we know this data has been collected using the same methods and the same training programme has been used for the past two years.

 

The season has now wound down at Rotopounamu. The 1150 bait stations were cleared and the 50 traps were shut down at the end of March.Tracking tunnel results continued to astonish us with rat and mice indices sitting below 5% for the months of November, December and January.

One of the objectives in the Rotopounamu Management Plan is to maintain rat numbers below a 5% footprint tracking index during the spring and summer period to allow native birds to successfully reproduce. Rodent numbers haven’t been recorded this low at Rotopounamu since 2007.

 

Throughout the month of February, Project Tongariro intern students and DOC staff carried out the annual bird monitoring at Rotopounamu. This is the main form of outcome monitoring we undertake at this site. 500 bird counts have been completed however the results are yet to be analysed.

It has been a busy start to the season up at Rotopounamu involving lots of rodent control and monitoring. With spring well on the way the birds are out in abundance and the lake levels have dropped back down to ordinary level.

Contractors have been employed this year to undertake the baiting operation and new bait called PestOff 50D is being used. The contractors started in September, initially with fortnightly re-fills of bait stations, and are now re-filling stations on a monthly basis with the next fill due in mid November.

To determine how many rats and mice were in the bush prior to the season’s bait distribution, tracking tunnels were run in early September resulting in a rat density index of 69% and mice densities at 49%. After the first week of bait distribution, a second tracking tunnel operation was run with fantastic results. Rat densities had dropped to 5.7% and mice down to 30%. November tracking tunnels have just been run with more good news. Rats are now at a density of 1.4% and mice at 2.9%!! This result meets one of the conservation objective’s that ship rat populations are maintained below a 5% footprint tracking index during the months of October – February!

The 50 DOC200 traps around Lake Rotopounamu have been set for the season and have been baited with eggs and salted rabbit meat. So far 6 rats and 2 stoats have been trapped. These traps are a last line of defence but also a good advocacy tool for talking to members of the public about our project.

A big thank you to Kevin, Beth, Shirley and Karen and their  families who have been out running tracking tunnel lines and checking traps.

Traps up at Rotopounamu need to be checked once a week so if anyone is keen to help out with this that would be great – it’s a great reason to get out and enjoy the walk.

The sixth year of the Mt Pihanga/Rotopounamu project has passed in the blink of an eye, though perhaps it hasn’t seemed so to the worthy people who helped carry all those sacks of poison bait up the hill through the summer!  This year we received welcome financial support from the Department of Conservation (DOC), Environment Waikato, Land Rover, the Pharazyn Trust and WWF.  The project is a partnership between Project Tongariroy and Department of Conservation.

November 2007 saw a drop of 1080 over the Pihanga project area by the Animal Health Board. The rodent and mustelid populations were closely monitored as they fell to zero.  Baiting using Diatrac to control rats began in early September 2008 following a tracking tunnel round in August that showed a rat relative abundance of 16%. Baiting took place over 350ha and 572 bait stations (Stage 1 area) and was checked for taken or spoiled bait and replaced every fortnight until all bait was completely removed at the end of February.

The target of reducing rodents below 5% was not met and rat levels rose to 58% in December, a serious increase, though they dropped to 26% by February 2009. In the same period mice abundance leapt to around 70% and remained at that level for most of the season. This difficulty in controlling rat numbers this season is in line with similar projects in other parts of the country and may be the result of especially abundant natural food in the bush this year.

As a test of how our efforts are affecting the native wildlife of the bush we monitor a number of species. Monitoring of birds continued with five-minute bird counts of all birds, and tomtit distance sampling. Five-minute bird counts appeared to show a decrease in the observation of a number of species, but both techniques produce reliable results only in the long-term. Results of monitoring populations of weta, bats, Dactylanthus and white mistletoe showed that these species appear to be stable.

50 DOC200 traps were run around the Rotopounamu footpath and caught a total of 97 rats, 28 stoats, a weasel and a mouse between October 2008 and February 2009. The effect of these traps on the pest population is small, but this season once again proved their use as a tool of advocacy in dealing with the general public visiting Rotopounamu.

Work has continued on extending the area of bait stations to cover over 500ha, which will improve our effectiveness in reducing rat reinvasion to the core area as well as protecting a great area of forest. This winter is a beech mast and so rodent populations will gain a head start in repopulating the bush, but by hitting them hard at the start of the 2009/10 season over a greater area and then keeping the numbers low, we hope to prove that rats can be controlled sufficiently to allow native wildlife to prosper.

Heather also took a significant knock this season when the Department of Conservation sprayed populations of this invasive weed on the summit of Mt Pihanga and around Lake Rotopounamu.

 

  Read more about this project...

  How YOU can become a volunteer...