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Recent analysis of long-term monitoring shows low possum numbers in a South Westland valley are contributing to increases in native mistletoe.
This summer, visitors venturing into the remote Hope River valley can spot scarlet, red and yellow mistletoe flowering in the forest.
As well as adding a festive splash of colour, New Zealand’s mistletoes provide nectar for forest birds and geckos. The plants are semi-parasitic, drawing nutrients from host trees while also photosynthesising some of their own food.
Department of Conservation South Westland operations manager Wayne Costello says New Zealand mistletoes flower between December and January but remain under threat from possums.
“Mistletoe is a highly preferred food for possums – often considered the ‘ice cream’ plant for this introduced species.
“In the Hope River valley, mistletoe has been monitored since 2006. Results show the population has increased by 2.34 per cent per year, equating to an overall 57 per cent increase over 19 years of monitoring.”
Wayne says the findings suggest possum management in the valley, including aerial 1080, has been effective in maintaining healthy populations of possum-sensitive tree species.
“Mistletoe is an indicator species, which means that if it’s doing well, other species in the forest are also likely to be in good health.
“It’s great to see predator control paying off in the long term. The results give us confidence we are making a difference, and it’s heart-warming to know this plant, which plays an important role in a healthy ecosystem, is on the rise and can be enjoyed by people visiting the valley.”
Mistletoes were once widespread in New Zealand beech forests but, due to possum browse, are now absent from many areas.
Possums arrived later in South Westland than elsewhere in New Zealand, meaning that when pest control using 1080 began in the 1990s there was still a mistletoe population to build on.
