June 2018
Winter Activities
As expected in winter catch numbers in the trapping lines are low.
Volunteers assisted DOC with a feral cat trapping project after a number of cats were seen on a trail camera. This operation was successful and trapped all the cats seen on camera.
Kiwi Deaths - Peter Hale
Some of you may not be aware of this recent article on little spotted kiwi deaths.
This highlights avian malaria and disease in general, an issue that flies under the radar of many involved in conservation. Malarial parasites have been found in approximately 35 different bird species in New Zealand with a higher prevalence in non-native species. Deaths have been recorded in great spotted kiwi, hihi, mohua, tieke, dotterel and blackbird.
I was fortunate enough to have been involved in the investigation of a disease outbreak among saddleback on Long Island and Motuara Island in the Marlborough Sounds. This turned out to involve both avian malaria and the avipox virus. Some of you may have seen the typical head and leg lesions associated with the avipox on robins in particular.
The blackbird carries at least 3 malarial strains and because they are commonly infected they are considered to be the likely source of infection in many of our endemic/native birds. There are 2 post-infection phases: a short acute phase which has the most impact, and a subsequent chronic phase that can last the bird’s lifetime. Relapses of acute attacks can occur.
New Zealand has 12 endemic and 4 introduced mosquito species. The exotic Culex quinquefasciatus is the most concerning as it is increasing in abundance and spread along with other endemic and exotic species, and is responsible for the extinction of half of Hawaiian Island endemic bird species. Climate change (plus land-use change) has been strongly associated with increased infection rates worldwide.
Here at Nelson Lakes, PhD student Chris Niebuhr recently spent 3 seasons researching the influence of altitude on avian malaria. His findings support the hypothesis that disease, in addition to predation and competition, could have a role to play in the observed decline of bird species in the Park, something that was not on the radar in this report. Predator Free NZ Trust also wrote an article on the Nelson Lakes research last year.
Translocation of endangered species is an integral part of conservation in New Zealand and the relative exposure of birds to malarial parasites (and other diseases) at both source and destination needs to be considered. Reports are indicating that avian malarial infections may be restricting the success of some of these. All official translocations now involve a rigorous process which includes disease screening.
Stoat Gut Contents - Peter Hale
Friends of Rotoiti and DOC trap stoats in the alpine region of the St Arnaud Range and Jamie McAulay, an MSc student from Otago University, has been doing gut analysis of stoats caught by us in both the alpine and bush areas here as part of his research into the diet of stoats in the alpine zone. The attached Instagram photograph shows the gut contents from just one stoat caught in the alpine zone.
Lead Poisoning in Native Birds - Peter Hale
Most of you will probably have read this NZ Herald article on lead poisoning in Wellington kaka. I find the Herald reporters write excellent environmental articles and you only have to compare their report to that of the Dominion which missed commenting on water sources.
Back in 2016 I drew your attention to this article on lead poisoning in tui . This raises serious concerns as tui are nectar/insect feeders so the lead was coming from sources other than lead roofing fixtures. Of course we used leaded petrol for many years and this is a known source of environmental contamination.
The Wellington City Council gave an excellent talk on domestic cat management at the Tasman Biodiversity Forum in 2016. During the talk the councillor provided the statistics of native/endemic birds caught by cats which reflected the halo effect from Zealandia. A number of the bird species caught were birds such as tieke and hihi which would not survive on the mainland outside an exclusion fence. Post-mortems on these birds revealed that a number of species showed unexpected levels of lead which was a surprise in nectar/insect feeding birds. Lead poisoning causes birds to become listless, spending more time on the ground hence becoming easy prey for cats (and stoats in non-urban environments). Window strikes cause a similar problem and lead poisoning could be a contributing factor in this situation.
As I always say nothing in nature is ever straightforward, heavy metal poisoning is another contributing factor in the decline of our endemic/native species. A few years back a kaka died in a holding enclosure in the Able Tasman National Park, post-mortem analysis showed high levels of cadmium. Cadmium levels in our environment (and the rest of the world) have been of concern for decades with the use of superphosphate fertilizer being one of the main sources of contamination here in New Zealand.