Native birds thrive after pest control
Pest control in New Zealand works, and about seven years of pest control is needed before factors start to swing in favour of endemic birds, a new meta analysis of New Zealand mainland ecosanctuaries has found.
‘‘This study provides some of the strongest evidence worldwide for the benefits of pest control on mainlands,’’ said Dr Rachelle Binny of Manaaki Whenua-Landcare Research.
‘‘Our data show that after about seven years of being pestfree, endemic birds become abundant enough in ecosanctuaries to outcompete . . . exotics.’’
‘‘We showed that birds, invertebrates and plants are benefiting from pest control in ecosanctuaries but not all species benefited to the same degree and some species actually declined.
‘‘This is because, aside from pests, other important factors – competition for food or nesting sites – also shape how populations change over time,’’ she said. ‘‘After about seven years of pest control, competition or other factors is strong enough to drive declines in exotic birds, while endemic species [those found only in New Zealand] continue to recover and thrive,’’ she said.
Binny and seven other researchers analysed data from
16 mainland ecosanctuaries that had been undertaking pest control and ecological restoration from seven to
22 years.
The mainlands studied were the North, South, Stewart and Great Barrier islands, places where rats, possums and stoats must be eliminated if PredatorFree 2050 is to be achieved.
Many of these datasets had never been combined in a meta analysis before. ‘‘Our study covers more diverse ecosanctuaries and more measures for different species over a longer time period than previous publications.’’
Other studies have showed the benefits of controlling pests on mainlands, but these other studies looked at a narrow range of species or looked at many species in only one or a handful of sites, Binny said.
‘‘The new aspect of our work is the ability to compare different pest control strategies that are used across New Zealand’s mainland. This is the most comprehensive analysis yet that measures how much more net benefit there is from eradication, which is only feasible over small areas, compared to pest suppression which can cover much larger areas.’’
We know less about pest control than most people think, she said, and sometimes control hasn’t worked as expected.
‘‘By looking across many species and many projects, we’ve shown the overall biodiversity benefits that are typical under each pest control strategy, disentangled from biodiversity changes that are specific to a particular site,’’ Binny said.
‘‘Our findings provide new evidence that invasive pest control is an effective approach to ecological restoration.’’
Gut biome in wild and captive kiwi
Other researchers have found that the gut biome of captive kiwi is less diverse than wild kiwi. ‘‘We found that captivity was a signifiant predictor of the kiwi gut bacterial and fungal communities,’’ wrote lead author Priscilla San Juan in a study that has not undergone peer review yet. ‘‘Captive samples had lower microbial diversity and different composition when compared to wild samples.’’
The researchers analysed faeces samples from 68 wild and 38 captive brown kiwi on the North Island.
While the researchers were not able to draw conclusions about kiwi welfare, they suggested that factors shaping captive gut biome may include artificial diet, sterile built environments and human interaction.
It is increasingly understood that gut biome has an important role in health across a range of species.