Avian
malaria, caused by protozoan blood parasites of the genus Plasmodium, is a concern for native New Zealand birds; this
mosquito-borne disease has impacted both captive populations and wild
individuals in the country. However,
whether or not it is a cause of concern to native, wild populations is still
unclear. In Hawai’i, avian malaria has
been a major factor in the population declines of native forest bird species
and limits the elevational distribution of many remaining species. At our study site (Nelson Lakes National
Park, South Island, New Zealand), declines in native forest bird abundance have
been reported over the past 30 years.
Avian malaria is one possible cause of these declines, since they
generally occurred at lower altitudes where more potential reservoir birds and
mosquito vectors may be present. In
addition to the invasive mosquito vector Culex
quinquefasciatus, also found in Hawai’i, New Zealand’s native C. pervigilans is also suspected of
playing a role in malaria transmission, complicating our understanding of local
transmission dynamics.
Blood samples
were taken from native and non-native forest birds along an elevational
gradient (650m to 1400m) during three summers (2012-13 to 2014-15),
complimented with mosquito sampling. Here we will present our findings to date,
describing the avian malaria community detected (including data on host prevalence,
vector surveys, and Plasmodium spp. sequencing
results). We will also discuss our work
in adapting a malaria-forest bird epidemiological model (originally developed in
Hawai’i) to fit the New Zealand situation, incorporating both C. quinquefasciatus and C. pervigilans. This work has potential
for informing on management beyond avian malaria as well, as other
mosquito-borne diseases (e.g. West Nile, Ross River, and dengue) could
eventually make their way into New Zealand.