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Monitoring threats to kea in the Matukituki Valleys, Mt Aspiring National Park

Funded by Auckland Zoo Conservation Fund

The Matukituki Valley in Mt Aspiring NP is considered an important site for kea research with significant time and resources having been invested in the area since 2016. Both the West and East Matukituki Valleys have been surveyed by the KCT since January 2016 and up until February 2019, no nests or breeding activity had been recorded and only one fledgling sighted (when 6 fledglings were caught and banded). The reason for the lack of documented breeding activity appears to be a result of high predator numbers re-invading the area as well as adult mortality during pest control operations.

Helping Endangered Kea

Understanding how predators are impacting resident kea and breeding success is crucial for ongoing recruitment in the valley. As such from the end of 2019 onwards this project will aim to:

i) ascertain sub-adult and adult kea survivorship in the Matukituki Valleys;

ii) monitor kea breeding success in the study area and

iii) understand predator interaction and risk to a population of kea, east of the main divide.

This project will provide important information to support the larger DOC predator impact study on kea populations east of the main divide.


2019 Update

The status of the Matukituki kea population as of 2019 remains uncertain, however as no breeding activity has been recorded since monitoring began in 2016,  few fledglings or juveniles have been sighted and local pest numbers appear high (as recorded by the Matukituki Charitable Trusts (MCT) pest control programme and DOC tracking tunnels) it appears likely that kea in the Matukituki may have been and continue to be suppressed as a result of multiple 1080 operations and a high numbers of mammalian pests. This area has received two 1080 drops to control introduced pests (2015 and 2017) however there seems to have been little positive impact on the kea population.

This 2nd year of this project attempts to understand whether predators (particularly large predators such as feral cats) are present higher up in the valleys by increasing the number of cameras deployed, to fit more transmitters to adult kea to monitor survival and to continue tracking breeding activity and fledging success (if any) across years.

A total of 52 kea have been caught and banded in the study area up to the end of 2019.


Summary of outcomes (to the end of 2020) 

Please see below for fieldwork details.

Catch summary. An additional 17 kea were caught and banded and 8 transmitters (tx) fitted in the Matukituki Valleys in early 2020 bringing the valley totals to 68 kea banded and 14 transmitters fitted to date as part of the Kea Conservation Trusts Matukituki Kea monitoring project (funded by AZCF).

A 1080 operation was carried out on the 10th February 2020 resulting in six kea dying from ingesting baits. Only six transmitters remain active (two other transmitters on mortality were found to have either a failed battery or had been chewed off).

Blood lead levels. All kea blood lead tested have returned low levels. Only one kea (in 2019) has returned a high reading (>20ug/dL) since testing began in 2008.

Camera summary. 16 camera traps have been set up in the valleys as part of a larger DOC predator impact study on kea, with the view to extending these in subsequent years up from the valley floor. To date mammalian pest numbers (mice, rats, possums and stoats) have been found to be high. The first camera SD cards were recovered just prior to the 1080 operation (Jan 2020) after 1 month of activity and 27,000 trigger events were sorted, graphed and mapped by species. Species recorded included mice, rats, possums and stoats. No cats were seen. The second round of SD cards were recovered at the beginning of June 2020 (post-1080 operation) and 5,000 trigger events are in the process of being analysed. DOC tracking tunnel results pre 1080 showed rats tracking at 47% and mice at 76%. Post-operation in March these fell to 0% and 4% respectively and 1% and 8% in May. The MCT trapped 36 feral cats between May 2019 – May 2020.

Nest monitoring summary. Two adult females were successfully tracked to nests in the West Matukituki in spring 2020. Both of these nests successfully fledged all of their chicks (Isobel fledged 2 and Kia Kaha fledged 4). This is the first time successful nesting has been recorded in the monitoring area which is very exciting!


Summary of Outcomes 2021 (Jan-June)

Catch summary. Two catch trips in February – March 2021 saw 32 new kea banded, 26 of which were fledglings or juveniles. Our rangers estimated at least 100 young kea were present in the West Matukituki alone. Clearly there were many more than the two successful nests that were located. It is unclear why 2020 was such a successful breeding season however the 1080 drop in February 2020 was likely a contributing factor as pest numbers in the valleys (as recorded on our cameras) were heavily suppressed immediately after the 1080 operation. Four new transmitters were deployed on adult kea in 2021 bringing our totals to 100 kea banded since 2016 and 8 transmitters are currently active. One transmitter in mortality as of last year was recovered (found to have been dropped) and another has not been able to be recovered due to access (location of bird as yet undetermined).

Blood lead levels. Twenty-four of these new birds were also blood lead tested with three returning high blood levels (>20ug/dL). We will be working with local groups and DOC to identify the source of this lead and support its removal this coming spring.

Transmitter status. To be updated.

Camera summary. To be updated.

Nest monitoring summary. Females fitted with transmitters will be tracked from the end of June (start of the breeding season) to track their nesting status. Nest monitoring will begin as soon as active nests are found.


Project Outcomes

10-11th January 2020

Two days were spent in the Matukituki installing 15 camera traps (seven in the West Matukituki, eight in the East). The camera traps were set up using the same methodology used in the DOC Eastern Forests Project. One more camera is to be set up in the West Matukituki on the next trip, bringing the total to 16. Intentions are to place 16 more cameras in the field (eight more in each valley) next season.

A second January field trip will be conducted towards the end of the month. This will involve mortality checks of the adult kea with transmitters fitted, tracking of potentially nesting birds and catching and attaching more transmitters to adult kea where possible. The 15 installed camera traps will have the SD cards and batteries swapped and the meat removed for this round of monitoring. One more camera will be added to the West Matukituki to bring the total to sixteen.

Stoat captured on a trail camera in the East Matukituki Valley January 2020.

29 Jan - 1 February 2020

All cat trail cameras had their SD cards swapped and were set to a ‘dry round’ of monitoring in the East and West Matukituki Valleys.

The weather allowed for four catch sessions on Cascade track and three catch sessions at French Ridge Hut. A total of 17 kea were caught on this trip (12 on the Cascade Saddle track and five at French Ridge Hut).

Eight transmitters were fitted to adult kea (five males and three females). Bands were fitted to all birds caught and samples and measurements were recorded for the database.

Tom Goodman releasing a newly banded kea in the West Matukituki Valley Jan 2020.

February - December 2020

  1. All photos taken on the motion censor trail cameras need to be analysed for presence of cats and other species.
  2. Another trip to change SD cards is scheduled for the 15th to 17th of February. This will involve placing erayze and rabbit meat in the cages for another ‘meat round’ of monitoring.
  3. A 1080 drop is scheduled for Sunday 9th February (finishing Monday 10th February with Tuesday 11th as a backup). With 13 transmitter-fitted kea in the drop zones within the West and East Matukituki Valleys, there is an opportunity to monitor kea throughout and after the drop. This requires a number of Sky Ranger flights (one before the drop and two to three after the drop) to monitor kea mortality. Any mortality signals will be tracked on foot to determine their status (dropped transmitter or dead kea). Any mortalities will be taken in for post-mortem.
  4. Regular foot tracking and aerial flights are to take place throughout the year to check signal status of birds. A requirement for the cat study is that any dead kea are located as soon as possible for an accurate post-mortem.
  5. From August on, all adult kea can be tracked to locate any nests in the West and East Matukituki Valleys. This will go towards the nest survivorship study.

Monitoring outcomes of study kea through 1080 operation

A 1080 operation was carried out on the 10th-11th February 2020 by the Department of Conservation. A skyranger (remote tracking) flight carried out just prior to the drop on the 9th, found 10 of the 13 kea fitted with transmitters in the drop zone. Signals from the other 3 transmitters were not picked up at that time. It was later confirmed that a further 2 kea were within the operation area and 1 kea had chewed off its transmitter prior to the drop taking place (this was recovered at a later date). As such 12 out of the original 13 kea were ultimately confirmed as present and able to be monitored throughout the operation.

Tracking outcomes: A skyranger flight carried out on Thursday 13th Feb found 2 transmitter signals had switched to mortality mode. As a result, a person was sent in on the 14th and 15th to track down the signals to recover them to ascertain the bird's status (i.e. whether dead or a ditched transmitter). At this time neither transmitter was located however a further 3 mortality signals were picked up. Four birds were confirmed alive at this time.

A full team was sent in during the next fine weather window (19th and 20th Feb) and 6 dead adult kea and 1 dropped transmitter were recovered. Five kea were confirmed alive (either a signal or sighting returned), however, a signal could not be found for one female who had previously returned a signal on the 15th Feb.  She was finally confirmed alive during an aerial tracking flight on the 18th Feb.

The recovered bodies were sent to Wildbase Hospital and Landcare Research for necropsy and toxicology testing. Results of testing confirm death from 1080 poisoning. All kea had previously been tested for lead and found to have low levels.

Where to from here?

1080 has been shown to benefit kea populations in some areas (particularly remote locations) by suppressing introduced mammals that kill nestlings however if adult survival through 1080 operations is 56.8 % or lower, the cost is likely to exceed the benefits of increased nest productivity in subsequent years.

So why do some populations, such as the Matukituki Valley kea, seem more at risk to picking up 1080 than others?

At-risk populations may include those kea that are habituated to people (in particular, hut birds and those kea being fed by people), or which have high blood lead levels (which may make them more likely to scrounge due to impaired cognitive function impacting on the ability to forage natural food sources). The Matukituki Valley birds fall into this first category. However, there may be other factors that put certain kea at higher risk (time of year, individual behaviour, cultural learning and food availability etc) and until these risk factors are identified, more funding and research needs to be focused to identify robust and cost-effective mitigation measures as well as ongoing monitoring of these populations through operations.

As such, we advocate the following measures urgently be adopted to minimise harm as follows:

Immediately:

  • Review all current data to identify what makes a kea population at-risk;
  • Identify and research other potential risk factors;
  • Review all planned 1080 operations to identify which are likely to have at-risk kea populations.

For populations identified as at risk, operations should be postponed unless:

  • Research and mitigation measures are researched and implemented;
  • Survivorship is monitored and mitigation efficacy measured.

Trail camera outcomes January – December 2020

Data (SD) cards from all 16 trail cameras were swapped out every  6-8wks throughout 2020 (January, March, June, July, August) and camera data analysed.

In September – October these cameras were pulled out of both valleys and along with a further 8 cameras were reset to extend the study area.


Breeding season outcomes August – December 2020

This nesting season marks a milestone in the Matukituki kea threats monitoring. It is the first time any of our monitored females have been tracked to active nests. Isobel and Kia Kaha both nested this year!

A total of nine nest checks were undertaken between August and October to visually confirm nest statuses and change SD cards and batteries on cameras monitoring entrances and nest bowls at both nests. The nests were observed at all phases from eggs to young chicks to almost-fledged chicks. There were no predator incursions detected on the cameras and no sign of predator visits outside or inside both cavities. There is one more nest visit to be completed (November) to confirm the chicks have fledged and to remove nest cameras.

Isobel’s choice of nest marked another first for kea research. Her cavity is the first found in the alpine zone, about 150 metres above the treeline. Kea usually nest 100 – 200 m below the treeline in beech forest. Isobel was found to have 4 eggs in her nest and successfully hatched and raised 2 chicks.

Kia Kaha was found to have five eggs in her nest and successfully hatched and raised 4 chicks (photo above).

Nest protection efforts – trapping network

A line of ten traps was installed by a team of KCT and Matukituki Charitable Trust volunteers in September aimed at protecting Kia Kaha’s nest from pests approaching from the valley floor. This trapline was additional to an already existing trapline running along Cascade Track above the nest and to the DOC 1080 aerial predator control operation at the beginning of the year.

Traps were placed at a distance that was unlikely to attract predators to the nest. We would like to say a huge ‘thank you’ to the Matukituki Charitable Trust for providing the traps, helping install them, and regularly checking them. No predators have been caught in these traps to date.

The Nest Protection Team (L to R) – Geoff Marks (MCT), Tom Goodman (KCT), Kim Newton (KCT), Stu Thorne (MCT), Nicki van Zyl (DOC), Paul Hellebrekers (MCT).

Project Outcomes 2021

25 February – 2 March

A catch team went into the West Matukituki Valley and were very pleased to report a high level of kea activity in the valley (resulting in a few damaged tents and equipment!). A total of 30 kea (26 juveniles/fledglings and 4 adults) were banded while all adults were fitted with transmitters (two females with egg-timer transmitters to enable follow-up nest monitoring and survival during the breeding season and two adult males with long-life transmitters to monitor survival). Lead testing was carried out on 24 kea with results showing 3 at dangerous levels of >20ug/dL (two of these were over 50 ug/dL).

8 March

A follow-up tracking flight was also carried out to check transmitters hadn’t gone into mortality or been chewed off. Results are pending.

22-24 March

A second trip on foot by the team was carried out late March to change over SD cards and batteries on all predator cameras, to recover Radicals transmitter on mortality (which was found to have been chewed off) and to follow up with birds in the East Matukituki. A further 2 kea were caught and banded (bringing the total to 100).

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