Monitoring the endangered rock wren within the alpine basins of the Makarora catchment

Focused on two alpine study sites; the Crucible Basin within the Siberia Valley and the Upper Lucidus/Castalia Basin within the north branch of the Wilkin Valley with extension into adjacent basins. Rock wren monitoring transects defined and surveyed for both sites during 2017/2018. The results of this survey work guided deployment of alpine invasive mammal traps and subsequent installation of Celium remote trap monitoring technology to improve predator control trap servicing efficiency and provide additional information on predator movements (first image shows a male rock in moult).

Following ABT’s initial rock wren monitoring transect surveys undertaken during summer 2017/2018 and following observations during 2018/2019 we have now commenced colour banding of individual birds.

A colour banded rock wren at Lake Crucible

This bird monitoring method helps to identify individual birds, confirm rock wren territories and provide information on dispersal of post-breeding jeuveniles whilst providing an indicator of predator control success. We can also learn about moult strategies for this unique alpine passerine.

Specialist mist nets are errected within know breeding territories and a audible lure is used to encourage individuals into the net. The mist net shelves are kept low as rock wren flight is limited and birds often forage close to the ground on terrestrial insects (spiders, moths, beetles and flies) and berries from plants such as Muehlenbeckia axillaris (below).

Succulent fruits of Muehlenbeckia axillaris. Several rock wren have been noted foraging from this plant during February within the Crucible basin.

All birds are carefully extracted from mist nets by a NZNBBS certified bird bander. Three colour bands (two on the right leg, one on the left) are carefuly applied, biometric measurements taken and any observations on moult or condition are recorded.

A mist net (9m) located within suitable rock wren habitat.

A combination of adult and jeuvenile birds have been banded during 2019/2020 season. Images below show a adult male with a prominant supercilium and a weight of 14.6g. This bird appears to have gone through post-breeding moult (moulting is the periodic replacement of feathers by shedding old ones whilst producing new ones).

Male rock wren post- breeding moult (March 2020).
Rear of male rock wren showing new primaries and tail feathers.

 

 

 

 

 

 

 

 

The survey work provides addition information on rock wren in an area which has not previously been investigated at this level, complementary to existing study sites such as in Fiordland, and Haast, contributing to overall knowledge to promote effective future conservation management for this nationally endangered species. We look forward to further progressing rock wren monitoring during the next breeding season 2020/2021.

The Crucible basin, one of the Makarora catchment alpine study site for the endangered rock wren. During December a haze of ash and dust from the Australian bush fires could be seen on the top of the lake.

ABT’s rock wren protection and restoration programme forms part of a broader threatened species project for the Makarora Catchment from “ridge to river” and is complementary to the Department of Conservation Predator Control Plan for Makarora as referenced within ABT’s Community Agreement and in accordance with NZ Biodiversity Strategy i.e. to maintain and restore viable populations of all indigenous species across their natural range and maintainance of their genetic diversity.

References:

Melville, D S (2013 reprint). Moult in birds. British Trust for Ornithology. Guide 19.

Melville, D S (2011). NZNBBS Bird Banders Manual. DOC, Wellington.

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.

Return of the kaka at Makarora

This season has seen the return of the South Island kaka (Nestor meridionalis) in the Makarora valley as recorded in the early days by local residents and as documented partly by the work of the late Peter Child (1980’s).

ABT’s baseline forest bird survey was undertaken on four occassions for the Shrimpton/ Charteris beech/ podocarp forest during 2018/2019. Results recorded a total of 24 species; 14 endemic, 2 native and 8 introduced. A pair of kaka was recorded utilising the forest habitat in spring and summer during the survey.

South Island kaka
Aspiring Biodiversity Trust 5 minute bird counts undertaken during December 2018 for Shrimpton/ Charteris Forest

Regular sitings of a flock of up to 13 kaka were first reported during this spring by local residents and have been seen and heard reguarly since by many people including myself during several stays in the valley. Historically the highest total in any one valley within the region has been documented as 14 (Child’s 1981).

Their jurassic like raucous sqawks and melodic social calls can be heard most evenings and mornings and are often seen flying between areas of forest, residential gardens, the motor camp and commuting over the highway to further foraging habiatat.

Long term resident Gary Charteris “It’s like how it used to be 15-20 years ago”.

Gary a keen nature enthusiast observed all 13 kaka in one of his mature trees on the 11 December and noted the characteristic white head of many, a feature of the South Island kaka. Sarah Forder a more recent resident observed up to 10 kaka feeding on her cherry trees. They have also been noted striping away the the bark of forest deadwood whilst feeding on insect larvae. The local school below the forest have been enjoying the commuting activities of these remarkable birds.

Local resident Gary Charteris sharing his thoughts on the latest kaka sightings in the valley with Linda Hufton an overseas visitor.

The magnificient endemic scarlet mistletoe (Peraxilla colensoi) present in the beech forest is another favourite of the kaka, who enjoy the nectar and the flowers along with small flocks of yellow-crowned karkariki (Cyanoramphus auriceps). Remanent parts can often been seen on the forest floor below where birds have been feeding.

Discarded parts of the endemic scarlet mistletoe grazed upon by kaka and other forest birds
Field signs of kaka foraging on insect larvae burrowed within forest deadwood

All though little is know about the kaka population in the area, it is thought that they commute from the West Coast. Numbers appear to have reduced to 3 or 4 since recent sightings so parhaps the remainder of the flock have commenced their journey back towards Haast after the summer forest food peak. More information on the range of kaka and their breeding habits within the region would be beneficial to the future conservaton of this species.

Its now mid January and the sound of the kaka seems to have simered down. The characteristic dry-thrill call of a long-tailed cuckoo or koekoea noted flying overhead is another species recorded in January for this area of important biodiversity value. Lets hope with the help of ongoing community predator control programmes and forest bird monitoring next spring continues to see the return of the kaka and resident forest bird species continue to flourish!

A yellow-crowned kakariki, a parakeet which appears to be doing well this season with small flocks (3-5) frequently observed.

 

 

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 tonga.

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 🙂

Updating Whio/ blue duck records for the upper river catchments of the Makarora

One of ABT’s core purpose is the collation and updating of threatened species records within the Makarora Catchment to help facilitate and inform appropriate application of invasive predator control.

ABT have been updating records for whio/ blue duck Hymenolaimus malacorhynchos to help ascertain the current status of this ancient endemic waterfowl species within the upper reaches of the Makarora Catchment. No formal inventory has been completed for this species since the work of the late Peter Child during 1970’s/1980’s.

To date a specialist contractor Paul van Klink and his protected species survey dog (Hoki) has been commissioned to undertake walkover surveys for the upper Wilkin, the Siberia and the Young Valley.

Whio surveyor with protected species survey dog in the North Wilkin Valley

From the results of these walkover surveys and the addition of recent incidental records it is promising to see that there remains a remnant population. Numbers are low and in some cases are limited to just male individuals, a high prevalence of unpaired males on rivers without predator control is often common as nesting females are more vulnerable to mammalian predation. However, evidence of breeding success has been recorded with observations of pair bonds and a fledgling bird.

Adult male whio

This valuable survey work continues to expand for the region with the future aim of restoring viable, sustainable populations of whio/ blue duck within the upper river catchments of the Makarora for future generations.

Down stream of Lake Lucidus, North branch of the Wilkin with Hoki
Whio survey dog in action (Hoki). Image credit P van Klink

Reference

Child P, (1981). Birdlife of Mount Aspiring National Park. Scientific Services No.4. Department of Lands and Survey. Head Office, Wellington, New Zealand.

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).

Endangered bird life of the Crucible Basin, Siberia Valley

ABT’s rock wren transect survey monitoring programme for the 2017/2018 survey season includes the Crucible Basin situated within the Siberia Valley. Monitoring surveys aim to provide an updated baseline on threatened species and allow repeatable monitoring for rock wren within the Makarora catchment to help guide appropriate future conservation management in relation to invasive mammalian predators.

Kea (juvenile male) at Lake Crucible looking towards the Gillespie Pass, Makarora

A number of rock wren pairs were recorded present within the bolder-field and moraine habitat and evidence of adults foraging invertebrates for nestlings was noted. During rock wren surveys the Crucible Basin was also noted as an important site for kea as well as rock wren. On both survey occasions seven kea were observed, mainly this years juveniles with their characteristic yellow ceres, eyelids and pale crowns. Kea parents were observed feeding young fledglings regurgitated food and a rock bivi frequented by kea was found close to Lake Crucible.

A pair of rock wren below photographed during their diagnostic bouncing display on their long legs with occasional emissions of characteristic sharp tweet calls http://nzbirdsonline.org.nz/species/rock-wren#bird-sounds.

Male rock wren
Female rock wren

ABT are collaborating with DoC to extend current mammalian trapping efforts for rock wren within the alpine environment of the Makarora catchment.

Kea fledgling (2017/ 2018) Lake Crucible

All kea records in relation to ABT’s survey and monitoring have been forwarded to the Kea Conservation Trust to help inform a national kea database.

Generally our time at Crucible Basin was positive however, we did note an aerial drone trying to film kea and artificial feeding by visitors. These are two national issues where continued awareness raising is crucial for New Zealand’s threatened species. Image below shows a hunkered down kea looking up at the drone buzzing above whilst others disappeared beneath boulder habitat.

Young kea looking up at overhead drone – Lake Crucible

Confirmed presence of a rock wren colony….

Rock wren of the Wilkin Valley

The Aspiring Biodiversity Trust are pleased to report the confirmed presence of rock wren at the north branch of the Wilkin River following the undertaking and setting up of a recent (Jan 2018) transect monitoring survey.

rock wren - Rachel Hufton
Rock wren (adult female)

Rock wren Xenicus gilviventris is the only true alpine New Zealand bird species and is currently classed as globally endangered under the International Union for the Conservation of Nature (IUCN). Peter Child’s (1980) work was the first comprehensive bird survey of Mt Aspiring National Park for rock wren.

Rachel Hufton rock wren survey
Rachel Hufton surveying rock wren habitat at Lake Castalia, north source of the Wilkin River.

The main threat to this species is predation from invasive mammals such as stoats and rats now known to be present within alpine environments. The results of the survey will help inform and guide existing and future conservation management for rock wren. Monitoring transects will also be repeated in subsequent years to allow more informed decisions to be made in relation to this indigenous alpine specialist.