New Zealanders, also known as the ‘kiwis’, are known for tramping up great mountains, and travelling around the globe. For the actual kiwi bird, their adventures are limited to islands and protected environments. Even our New Zealand mascot, Goldie the kiwi, manages to ‘fly’ all around the world, which I’m sure would make the national birds jealous.
That’s not to say that actual kiwi don’t get around. Our national icon is the most translocated bird in New Zealand. We have been translocating kiwi since not long after the Treaty of Waitangi (1840) due to predation and habitat loss, often with limited success. When we try our hardest to save populations through transfers, most or all birds die. So, we created protected (fenced) sanctuaries that allow a safe environment for kiwi and other native species to thrive. But after decades of conservation work and relocating kiwis out of their homes to a safer habitat, are they truly happy in their new homes?
Fenced Sanctuary – Zealandia. Image by Russellstreet
Methods for successful translocations have been developed. Methods, including the introduction of Operation Nest Egg (ONE), allows the hatching chicks to become mature before releasing into the wild. These methods has required the involvement of community groups, iwi and hapū. However… there are no resources that include information from past kiwi translocations, so we don’t know the past outcomes, whether they were effective, or how to improve them — which is wild!
Researchers at Lincoln University, Peter Jahn and James Ross, and other colleagues reviewed 102 kiwi translocation projects (mainly from the last four decades — older information having been lost or ‘poorly documented’), and they examined the mitigation translocations and rehabilitation releases. But how do you define a ‘successful’ translocation?
We can’t assume that if we release birds into a new environment that everything will magically lead to success. We must investigate if the kiwi population can settle in, grow in numbers and maintain a healthy balance on their own for it to succeed long-term. The primary goal of translocations is to “establish or restore a population with a high probability of persistence”. Unfortunately, kiwi behaviours have made it hard to grow a population, as they are irregular breeders and take several years to reach sexual maturity.
To address this, objectives were set for releases:
- To grow all kiwi populations by at least 2% per year.
- To sustain genetic diversity, each translocation will have at least 40 unrelated individuals released (a ‘founder population’).
- A minimum timeframe of 15 years is required for the population to grow (and adapt to its new environment).
By collecting data and analysing the translocation trends over the decades, we can better understand how different projects affect the survival of kiwi taxa.
Stewart Island Brown Kiwi (Tokoeka). Image by Jake Osborne
Since 1863, there have been 102 translocations, with an impressive 76 kiwi translocations just in the last 20 years. Translocated kiwi species included: Rowi, Great Spotted Kiwi, Little Spotted Kiwi, Tokoeka, and Brown Kiwi. Most of the release sites (63% since the 1860s) were in the North Island or on offshore islands (sorry Lincoln — too much farmland). However, 20 of these projects’ reports do not exist or are unavailable. But here’s what is fascinating… just over half of the translocations (58%) introduced kiwi taxa where they were not seen before (a giant leap of ‘kiwi-kind’)!
In the past, effects to reduce harm for the kiwi were deemed as an ‘emergency’ to secure populations. Recent translocations cited ecological restoration and supporting kiwi taxa across different areas as a priority (which supports natural differences, and resilience – perfect for long-term conservation outcomes)!
Unfortunately, not all kiwi species have received the same level of attention. Those with more attention are spoilt with support (more management) and obtain an improvement in their conservation status. Other kiwi species are not as lucky, such as the Great Spotted Kiwi, Fiordland Tokoeka and Rakiura Tokoeka, as their conservation status has worsened. So even though translocation effort aims for an improvement in kiwi populations, other factors, such as population sizes and lack of predator control, make this already difficult job… even more challenging.
If you look at past scientific literature on initial survival of released birds, these translocations will be reported as ‘successful’, which seems good, right? But are they ‘self-sustaining populations’? Only one project (Zealandia) has been considered as ‘successful’ due to having an increased population. Even worse…. there is little information on the genetic make-up of the new population (which defeats the purpose of becoming a long-term project).
Little Spotted kiwi at Zealandia. Image by Kimberley Collins
For future translocations, the number of releases should be adjusted (by changing the total number kiwi released in a specific area) depending on the situation — for example, when there is a low founder population, or a high mortality rate. If a population is not looked after, this can result in reduced fitness and genetic variability. Having a database that holds the records of all the kiwi translocations would make it easier to analyse the factors that could influence kiwi populations.
So, what does the future hold for kiwi translocations? The main recovery goal, which was “restoring former distributions of all kiwi taxa”, has shown an increase in populations through translocations. Translocations have created new populations on islands, which can “fill in the gaps” in nature, which is a huge win! Guidelines suggest releasing 40 kiwi into a new population and that they are not related to the ‘founder population’ (this number can vary depending on specific factors to maintain high diversity).
As translocations start from newly established populations, it’s only through time that we will see if kiwi populations can further grow and maintain sufficient genetic diversity.
This article was prepared by Master of Science student Jessica Przychodzko as part of the ECOL608 Research Methods in Ecology course.
Jahn, P., Fernando Cagua E., Molles, L. E., Ross, J. G., & Germano, J .M. (2022). Kiwi translocation review: are we releasing enough birds and to the right places? New Zealand Journal of Ecology, 46(1): 3454. https://dx.doi.org/10.20417/nzjecol.46.1
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