Backyard behaviours key to preserve biodiversity

What we do in our own backyard can have a major effect on the biodiversity we see all around us, according to Dr Margaret Stanley, an associate professor at Auckland University’s  school of biological sciences.

Dr Stanley made her remarks at a gathering organised by Forest & Bird in the Oaks Retirement Village in Warkworth last week.

Dr Stanley said our urban areas have often been built in fertile areas and they are awash with native insect and bird life.

To give an example, she said one study undertaken in Lynfield, Auckland, had identified 253 species of beetle that were found nowhere else in the world.   

“In Australia, a third of the country’s endangered species live in cities. There is plenty of biodiversity in cities,” she said.

Dr Stanley said being able to enjoy a more natural environment had proven benefits to physical and mental health.  

Moreover, the preservation of natural features such as trees created a host of ongoing benefits, such as improving air quality, increasing carbon sequestration, reducing flood risk increasing shade and improving water quality.

There were economic benefits too, such as increasing the value of property, reducing energy costs and reducing healthcare costs.

But Dr Stanley said despite the obvious advantages, there were several threats to urban biodiversity that needed to be addressed and what was needed was a major public relations exercise to alert people to these threats and what they could do about them.

Among the threats she identified were “the chainsaw massacre” or cutting down of trees, unwise feeding of birds, light pollution, cats and weeds.

The chainsaw massacre

Dr Stanley said the pressure to build more houses in more concentrated areas had led to the indiscriminate cutting down of trees. An amendment to the Resource Management Act in 2012 had meant much fewer trees were now protected. She said some Auckland suburbs, such as Ponsonby, had lost 40 per cent of their urban forest.

“Self-interest trumps common good. People are just looking at their own space and they are not thinking about their community,” Dr Stanley said.

“I’m not sure what we can do about that except to remind people about all the benefits trees can give us.”

Unwise feeding of birds

Dr Stanley said almost half of New Zealanders feed birds in their backyards – spending $5 million a year on bread to do so. Bread and seeds were the most common foods fed to birds, but none of New Zealand’s native birds ate these foods. Rather, they relied on insects, fruit and nectar. Research has shown that where birds are fed with bread and seeds, there is an upsurge in exotic species of birds and a corresponding decline in native species. Dr Stanley said the university was currently investigating appropriate solutions of water and sugar, which could be recommended to bird lovers to encourage the proliferation of native species in their backyards.

Light pollution

Dr Stanley said light pollution in urban centres meant most people in cities could not see stars anymore. This was sad for humans but created even more problems for animals and birds, causing them to be disorientated, sleep deprived, lacking in energy and unsure how to navigate. She said there were many ways to fix light pollution such as shielding lights, pointing lights downwards so they don’t unnecessarily spill light into the sky, and through the extensive use of sensors. Sensors can detect when it is appropriate to turn a light on and then only when necessary.


Dr Stanley said cats frequently got out at night and posed a threat to native wildlife that could otherwise flourish in urban bush fragments. To make matters worse, New Zealand has the highest rates of cat ownership in the world. Moreover, cat owners were resistant to messages which would prioritise the environment over their cat. She said attitudes were different in Australia, where registering and micro-chipping cats was compulsory and cats were frequently confined to their own backyards, making use of outdoor cat runs.   


Dr Stanley said it was unfortunate that gardeners often favoured exotic species over native ones and a major public relations exercise was needed to persuade people to plant natives, which unfortunately have a reputation of being slow growing and not very pretty.

“But the good thing about native plants is they support native insects,” Dr Stanley said.

Dr Stanley said introduced species could easily explode and take over, like gorse.

“We have got 25,000 plant species in New Zealand and only 2,100 of these are native. The rest come from cultivated gardens and horticulture. Every year, another 20 jump the fence from the garden and start breeding in the wild,” Dr Stanley said.

She said garden centres could play a role in pushing native species more.

“We have got some beautiful, flowering plants,” she said.

In addition to preserving trees, Dr Stanley encouraged gardeners to plant lots of shrubs, creating plenty of groundcover for wildlife to flourish.   

“The trend to put artificial turf everywhere drives me crazy,” she said.