Kea are a ground nesting parrot which are vulnerable to predation by introduced mammals (particularly stoats, possums and feral cats). Research undertaken by the Kea Conservation Trust (KCT) and Department of Conservation (DOC) since 2009 show kea nests are regularly visited by these predators. Kea eggs, chicks and adult females are taken or killed as a result, both on and off the nest. Without robust and widespread pest control, both aerial and ground based poisoning and trapping, kea are at very real risk of extinction.
Recent research has demonstrated that benefits to kea populations from reduction in predator density through aerial 1080 operations, generally outweighs the costs of non-target deaths. Accordingly, the KCT encourages and supports the controlled application of both aerial (1080) and ground based (kea-proofed traps and bait stations) pest control methods to reduce the threat of predators to kea.
However some kea, such as those which exhibit high levels of neophilia (love of novel objects) and/or populations prone to scrounging at sites of human activity , are more at risk of ingesting 1080. As such, we also strongly advocate for ongoing review, research and monitoring for all pest control operations.
This should include:
- Reviewing all current data to identify what makes a kea population at-risk;
- Identifying and researching other potential risk factors;
- Reviewing 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.
Kea are killed by introduced predators
In Nelson Lakes prior to 2015, no 1080 was used. This kea population was intensively monitored between 1993-1999 by DOC and 2009-2012 by the KCT. In the 1990s, the population was healthy and stable with 11 breeding pairs producing an average of 10 chicks annually across that period (Kemp, 1999).
During 2000 and 2001 there was a double beech mast. Mast-seeding events increase the amount of seed available in these beech-dominated forests resulting in mouse and rat irruptions (sudden local increase in numbers) followed by stoat plagues.
Work by KCT researchers from 2009 -2012, showed that the kea population had decreased to just three breeding pairs producing a total of two chicks per year. Cameras placed at/outside the remaining kea nests showed regular predator visitation and predation events resulting in regular nest failures.
Kea productivity increases in areas where 1080 is used
The KCT has been involved in studies carried out by DOC which show that kea populations respond positively to the use of aerial 1080. In a 30,000 ha area of lowland rimu forest in South Westland, a study compared kea nest survivorship (kea chicks surviving to fledging) at a site receiving aerial 1080 (impact site) following a large rimu mast-seeding event and a control site where no 1080 was used. Nest survival rates in the control and impact sites, before the application of 1080, were 21% and 46.4%, respectively. After the application of 1080 to the impact site, nest survival increased to 84.8%, whereas it declined to 12.2% in the untreated control site.
This substantial positive effect of aerial 1080 on kea nest survival is attributed to the effective reduction of mammalian nest predators, particularly the secondary poisoning of stoats. (Kemp et al, 2018).
Some kea are killed by 1080 and ground based pest control
Between 2008 and 2016, a total of 222 kea were monitored through nineteen aerial 1080 operations by the Department of Conservation (DOC). Across six of those operations, 24 birds (10.8% of the total) died from ingesting baits (refer to Table 1 and Figure 2 below, from Kemp et al, 2019). Losses in separate operations ranged from 5% - 41% mortality (Kemp et al, 2018).
In February 2020, 12 kea were monitored by the Kea Conservation Trust (KCT) through an aerial 1080 operation in the Matukituki Valleys, Mt Aspiring National Park. Six of these died as a result of ingesting 1080 pellets — a 50% mortality rate in the all-adult sample.
Kea are also regularly killed by accessing ground based pest control although this number has yet to be quantified.
Why do some kea eat 1080?
Kea are an inquisitive species. In areas where they are habituated to investigating and picking up novel food items provided by people (junk food), they appear to be more likely to consume 1080 pellets , particularly when they have been exposed to non-toxic cereal pre-feed ( a palatable cereal bait used to train the target species (rats and possums) into eating a subsequent toxic bait). As such we strongly advocate no feeding of kea and for people to remove their rubbish from areas frequented by kea.
Research shows that kea at remote sites (>40km from human sites) and which have been subject to repeat 1080 operations, appear to be at lower risk from ingesting toxic baits. Kemp et al. (2019) demonstrated that the odds of survival increased by a factor of 21.3 at sites with repeated 1080 operations compared with first time treatments, and suggest this effect is possibly due to selection for neophobic phenotypes (individuals who might be less inclined to pick up novel objects like 1080 baits).
“Proximity to human-occupied sites where kea scrounge human food was inversely related to survival; the odds of survival increased by a factor of 6.9 for remote kea, compared to those that lived near scrounging sites. High survival in remote areas is explained by innate neophobia (fear of new things) and a short field-life of pre-feed baits, which together preclude acceptance of poison baits as familiar food. Elevated risk to kea living near scrounging sites is explained by learned neophilia (love of new things), possibly exacerbated by lead poisoning.”(ibid). Lead poisoning impairs cognitive function, and may result in birds not being able to forage natural food sources, so that they instead scrounge easily accessed toxic baits.
In sum though, care should be taken not to simply characterise kea as either “at-risk front country” i.e. near human occupied sites or “backcountry” birds i.e. remote birds. There is increasing evidence that some birds travel between front country and remote sites, perhaps even on a regular basis (see satellite tracking data and Kea Sightings Database for evidence of long-distance individual movements).
Caution should also be exercised in assuming all populations with historical exposure to 1080 are less vulnerable to new 1080 drops compared to naïve birds, until more research into other factors is carried out. Other factors increasing a population’s risk may include individual behavioural or cultural learning characteristics yet unquantified. For example, some remote kea populations, such as that in the Murchison Mountains, display extreme neophilia and exploratory behaviour. These may not be “junk food” kea as such, but are attracted, and exposed to, repeated human activity such as trap setting. It is also well-known that particular individuals even within notable scrounge sites are considerably more neophilic and explorative than others.
Can any predator control method be 100% safe for kea?
Not at this time. Information gathered from researchers, hunters, trappers and DOC over the past 13 years show us that kea are highly inquisitive and resourceful and regularly investigate baits and kill traps intended for introduced predators. The KCT urges any predator control methods to be kea-proofed and encourages reporting of any kea deaths related to any method of pest control (as well as any kea proofing methods used) so that we may share this information and minimise further deaths. Please download our most recent Kea Safe Pest Control document.