Threatened Species Protection Expansion with assistance from Bill Day of Seaworks

The Aspiring Biodiversity Trust were out in full force on Tuesday and Wednesday (11 & 12 August), determined to increase the protection of our important threatened Taonga species in preparation for the upcomming breeding season. Bill Day of Seaworks kindly offered his assistance of considerable helicopter time; thanks to Lydia Bradey, ABT’s Patron recently awarded a New Zealand Order of Merit (ONZM).

A crisp early start at Makarora; Bill Day arrives for the initial health and safety briefing before take off into the backcountry. Left to right: Andy Longman, Lydia Bradey, Bill Day (pilot) & Anthony Coote.

Invasive mammal traps fitted with kea proof fixings were assembled locally then transported to Makarora by vehicle. Here the team (Anthony Coote, Lydia Bradey, Rachel Hufton, Karen Day, Andy Longman) were met by Bill Day (Director of Seaworks keen to contribute to indigenous biodiversity protection) in his B0105 helicopter, equiped with plenty of space for transporting predator traps into the backcountry.

The endangered alpine rock wren (juvenile) or pīwauwau, Crucible Basin.

Traps were droped at a number of locations including the upper Siberia, Crucible Basin,  upper/lower  Lucidus and Wilkin Valley. The locations are of particular importance for remnant populations of the alpine rock wren, the ancient blue duck (whio) and kea (as indentified by ABT surveys and monitoring) and will intensify current predator control regimes.

Trap drop at lower Lucidus – where the habitat of rock wren overlaps with blue duck/ whio territories.

Existing traps identified as triggered from Encounter Solution’s remote monitoring Celium technology were serviced.  The new traps will be fitted with detection nodes extending the alpine remote monitoring network. Stoats are currently active within the alpine environment (where rock wren are likely to be particuarly vulnerable in their current state of torpor durung the winter) and down to the river valley (where blue duck frequent whilst foraging for aquatic invertebrates or grazing from algae clad boulders).

Adult blue duck or whio within the upper Siberia Valley (Credit: Nick Beckwith)

The stoat Mustela erminea is a small mammalian carnivore native to Eurasia and North America. The Wilkin was one of the first New Zealand introduction sites back in 1885’s in an attempt to control rabbits. Usually the fur is chestnut brown with a white underbelly; the tail has a black tip and is the most distinguishing feature of this mustelid. Some stoats undergo a white moult during the winter in alpine New Zealand, the tail tip remains black as shown in the example below from our last trip.

An upper Wilkin alpine stoat (a varacious predator of indigeonous wildlife) displaying its pale coat aiding camouflage during the winter months. Note: animal captured humanely with DOC 200 trap.

Lydia Bradey and Bill Day discussing the importance of the work Aspiring Biodiversity Trust have been doing to date and taking a moment to appreciate their incredible homeland in what was optimal weather conditions. 🙂

Lydia Bradey and Bill Day expressing the importance of indigenous biodiversity protection and restoration (Upper Wilkin Valley), fundamental to New Zealand’s cultural heritage.

Aspiring Biodiversity Trust actively contributing to the goals of Predator Free 2050 and working towards local and national Biodiversity Strategys through collaborative engagement.

Acknowledgements

With thanks to all our funders, volunteers and incredible supporters particuarly Perry Brooks and Rich Raynes for predator trap assembly, the Department Of Conservation (DOC) for validation of landing sites and Backcountry Helicopters for remainder of team pickup on Wednesday.

Spring in the Makarora Catchment – From Ridge to River

Coffee break at Jumboland airstrip (the Coru Lounge)

With this seasons work programme in full swing, spring 2019 marks the installation of ABT’s upper river predator control for whio or blue duck (Hymenolaimus malacorhynchos) protection within the Siberia Valley and the Wilkin Valley. This follows previous walkover survey work with the aid of a protected species dog specifically trained in the detection of whio; New Zealand’s ancient waterfowl species, an important part of Makarora’s indigenous taonga.

A whio pair (also known as blue duck) recorded within the Wilkin Valley Feb 2019

Here remnant populations of whio still remain however numbers are low and fledgling survival is limited by the presence of invasive predators such as stoat and rat. This can often lead to a sex ratio imbalance as females tend to be more vulnerable when nesting and during moult. The new trapping networks join up with alpine trap lines to help extend invasive predator coverage for this globally endangered species.

Predator control traps delivered by Backcountry Helicopters into mid-Siberia Valley. Photo credit Pilot Blair

Spring is also the time to resume alpine predator control operations for rock wren and kea protection. New traps added and a number of stoats, and rodents had been caught over the winter months despite not all traps being accessible at higher levels due to the amount of snow still present (these traps will be serviced next visit).

Invasive mammal trap exposed from the snow at Upper Lucidus (September 2019).
A mummified stoat caught at altitude during the winter months

Rock wren pairs were active at the Crucible Basin but all was quite in the upper Wilkin Valley (where snow cover heavier) suggesting that this population may not of yet stired from their winter torpor. Kea were heard calling above the Siberia Valley  and one in the upper Wilkin.

Crucible Basin trap drop off with Backcountry Helicopters and logistical planning for the day ahead
Snow cover along the ridge of Lake Crucible looking towards Gillespie Saddle (Oct 2019). The characteristic call of the rock wren is often heard here.

Back in the lower river valleys of the Makarora and Wilkin, braided river birds have returned and are starting to nest again. ABT braided river invasive mammal predator control continues on a monthly basis throughout the year with the help of regular volunteers. Stoats, rats, hedgehogs and feral cats are being reduced to help improve fledgling success of endangered birds such as black-fronted tern, wrybill and black-billed gull. The Southern black-backed gull is a avian predator of endangered braided river birds and their chicks. Adaptive management of this species is due to progress this season also.

Makarora braided river habitat showing the Wilkin confluence and the head of Lake Wanaka

Acknowledgements

With thanks to all our volunteers, funders, partners and supporters 🙂

Alpine predator control progress – winter activity indicated

Since the installation of ABT’s alpine predator control programme for the protection of rock wren Xenicus gilviventri, stoats have been recorded in traps at 1200 m elevation (refer to spatial distribution map below) in areas of rock wren habitat and they are still being caught during the winter months.

Adult male stoat caught at 1200 m by DOC 150 (kea proof) trap.

During this winter, Celium remote monitoring technology has shows that invasive mammalian predators are still on the move during the winter and are being caught within the alpine environment where indicative rock wren territories have been identified.

Snap shot of ABT trapping data Feb – April 2019 for Castallia/ Lucidus

The real time data shows current available trap coverage at Lucidus/ Castalia on 8 August 2019 is mostly reduced at lower altitudes and representing a threat to rock wren territory (southern scree area above Lake Lucidus). The red symbols display trap triggers and the green symbols identify the remaining trap coverage available to passing predators. The data illustrate that there is currently no imperative to replace bait (probably due to low temperatures in the alpine environment or lack of predator food source), and that servicing requirements are only determined by available un-sprung trap coverage at this stage (potentially effective rock wren protection).

Real time data provided by Celium remote monitoring technology.

The Celium remote technology provides additional information on alpine predators such as commuting activity and time of capture. Most trap triggers appear to occur at dawn between 06:00 – 08:00 h at 1000 to 1200 metres.

Time and altitude of invasive mammal trap triggers and previous trap servicing occasions

Climate conditions are recorded showing decreasing daily temperatures towards winter at all three Hub Stations. Overall winter conditions are cooler at Castallia/ Lucidus relative to the Crucible Basin.

Celium Hub Station daily temperatures at three alpine locations.

We look forward to servicing alpine traps and resuming rock wren monitoring this coming season, once baseline temperatures have warmed up and the rock wren are out of their winter torpor. Hope to see this juvenile from last year!

Last years (2018/2019) rock wren fledgling

Acknowledgements

With thanks to all our volunteers, partners and the following funders; WWF, the Tindall Foundation, Otago Regional Council, Oceana Gold and the Otago Community Trust.

References

O’Donnell, C F J, Weston K A, Monks J A. (2017). Impacts of introduced mammalian predators on New Zealand alpine fauna. New Zealand Journal of Ecology 41: 01-22.

Weston, K A, O’Donnell C F J, van Dam-Bates P, Monks J M (2018). Control of invasive predators improves breeding success of an endangered alpine passerine. International Journal of Avian Science. Vol 160, Issue 4.

Celium Remote Monitoring Aiding Alpine Predator Control

The start of 2019 marks the installation of Celium remote monitoring technology for two key alpine rock wren sites within the Makarora Catchment. We are delighted to be partnering with Encounter Solutions on this innovative approach not yet trialled within the alpine environment.

Rachel Hufton with Celium Hub Base Station
Celium remote monitoring Hub at the head of the Wilkin River with Rachel to the left

The Celium platform is a low powered wireless network designed for the purpose of wide-scale rugged management applications. Celium consists of a range of communication devices called Nodes (attached to traps) equipped with sensors. The sensors are designed to monitor parameters such as the status of a pest control trap (below), which the nodes then communicate to the base station called a Hub. The Celium Hub transmits the data via satellite to the Celium cloud programme, which then sends a signal to the user via  a notification email or text message.

Trap node installed on side of DOC 200 (kea proof) invasive mammal trap

The Celium Platform can be used for predator control monitoring and also has potential application for monitoring climate/weather and wildlife. On this instance the installation intends to aid trap maintenance servicing efficiency for rock wren protection within remote areas.

Anthony with Simon (Encounter Solutions) checking that trap Node is communicating to the Repeater Hub via android software.

Encounter Solutions Director Simon Croft (below) enjoyed his time out in the field with ABT and gained a number of close encounters with New Zealands only true alpine specialist – the endangered rock wren. His technical knowledge was a valuable addition during the North Wilkin installation.

Simon from Encounter Solutions installing Celium Hub with ABT

Since installation there have been three invasive mammal trap triggers at the highest trap location points. We look forward to reporting back on what predators have been captured. More soon….

juvenile rock wren
One of this years juvenile rock wren (Makarora Feb 2019)

With thanks to sponsors; Otago Community Trust, WWF, the Tindall Foundation, Otago Regional Council and Oceana Gold.

Alpine predator control for the endangered rock wren Xenicus gilviventris

Rock wren protection installation

Classified as nationally endangered, the rock wren (Xenicus gilviventris) is New Zealand’s only true alpine specialist remaining in the mountains above the treeline for most of its life.  Following the results of ABT’s rock wren survey transect monitoring during Jan/Feb 2018 the team have been installing invasive mammal predator control within two key focal alpine areas. Areas include, the Crucible basin within the Siberia Valley and the upper Lucidus/ Lake Castalia, North Branch of the Wilkin.

Approach to upper Lucidus/ Castalia to deploy invasive mammal traps. Pilot Blair Backcountry Helicopters and Ecologist Rachel Hufton.

Invasive mammalian predator traps (DOC 200 and 150 models) were transported in to both sites on a suspended sling from a Hughes 500 helicopter. The traps were then distributed to designated locations extending and complementing existing predator control efforts within the locality.

Crucible basin rock wren protection deployment with Makarora’s Backcountry Helicopters

Site locations within the Makarora Catchment can be seen from the topograph image below. The North branch of the Wilkin and the Crucible basin are situated to the west of the Makarora River.

Population status

Rock wren are at risk from invasive mammalian predation particularly from stoats and rats but also mice. There is increasing recognition that invasive predators are widespread within New Zealand alpine zones. Recent work has found that humane kill trapping of invasive predators can increase rock wren breeding success within the alpine environment (Weston et al 2018).

The national population of rock wren is currently unknown but thought to be around 5,000 mature individuals (IUCN) with severely fragmented populations due to particular habitat requirements. The rock wren belongs to a unique ancient lineage of eight New Zealand wrens now only two species survive. The alpine rock wren and the rifleman Acanthisitta chloris, generally a forest passserine.

Male rock wren upper Lucidus/ Castallia

During both trips it was encouraging to observe a number of adult rock wren present busy foraging on invertebrate prey. Particularly, at Crucible basin following the late November snowfall. Most birds were male which may indicate females occupied on their nest sites.

Remote trap monitoring

With the aim of optimising alpine trap servicing efficiency and improving understanding of temporal and climate influences on predator trapping ABT have partnered with Encounter Solutions Ltd to install remote trap monitoring technology. The equipment will be installed in January for both alpine sites. This system has been applied to other trapping habitats but will be a first for the alpine environment.  If successful other remote rock wren habitats could benefit from use of this technology to aid predator control programmes.

Rock wren protection installation at Crucible Basin, Andrew Shepherd helping to distribute kea proof traps.
ABT’s Anthony Coote securing and geo-referencing mammalian predator traps at Lake Castalia.

Future populations

With dedicated effort it is possible that focused rock wren recovery at these sites could result in potential “source” populations of rock wren and expansion/ migration of numbers/ pairs into unoccupied habitat (Weston 2014).

With thanks to Otago Community TrustOtago Regional Council, Oceana Gold, Backcountry Helicopters Ltd, Tony Zimmerman trap supplies, Central Otago Hunting and Fishing, DOC Wanaka, Backcountry Saddles Expeditions, volunteers Nick Beckwith and Andrew Shepherd.

References

Aspiring Biodiversity Trust (2018). Alpine predator control plan for rock wren. Makarora Catchment Threatened Species Plan.

IUCN Red List of threatened species

Weston K.A. 2014. Conservation genetics of alpine rock wren (Xenicus gilviventris). Doctorate thesis.

Weston K.A., O’Donnell C.F.J., Van Dam Bates P. & Monks J.M. 2018. Control of invasive predators improves breeding success of an endangered alpine passerine.

Male rock wren Crucible Basin (Nov 2018).