Natural feeding preferred

Maureen Howard wonders if feeding backyard birds helps spread bird flu.

Could we be killing with kindness? In New Zealand, the science shows when we put out seed and bread in our backyards we are feeding exotic birds only — and by bringing species into close proximity, avian diseases such as avian pox are spread to native species.

Is it OK then to feed native birds sugar water? This apparently bird-friendly alternative involves putting out a specifically designed sugar-water feeder for nectarivorous birds like tūī, korimako (bellbird) and tauhou (silvereye) that normally consume nectar — a sweet liquid that some plants provide in return for pollination services. In New Zealand, nectarivorous birds consume the nectar of plants such as harakeke (Phormium spp), kowhai and tarata, in turn helping to pollinate these species.

The impact of feeding birds sugar water was the focus of conservation biologist Dr Daria Erastova’s PhD with the University of Auckland. She found that nectarivorous birds used sugar-water feeders more in winter than summer, preferred their sugar water sweet (one cup of sugar per litre of water), and despite the warmer temperatures birds spent more time at sugar-water feeders in Auckland than Dunedin. Importantly, Dr Erastova also found that nectarivorous birds in gardens with sugar-water feeders behaved more aggressively, were in poorer body condition, and were more likely to have a coccidia infection — a gastrointestinal parasite.

Compared with feeding birds bread or seed, sugar-water feeding is not bad for birds’ health, Dr Erastova says, so long as we choose a sugar-water feeder specifically designed for the purpose, we keep it very clean and we make it predator-proof.

However, "I just wanted to give a heads up to bird lovers that just like junk food can save you from death if you are starving, it’s not the best idea to eat only junk food for the rest of your life — that will make you sick." It’s the same with birds, she says.

Department of Conservation technical adviser Bruce McKinlay has concerns about feeding birds, too.

"It’s an uncontrolled experiment — these are complex ecological processes we are interfering with."

Mr McKinlay is part of a team preparing for the inevitable arrival to our shores of "bird flu", a variant of highly pathogenic avian influenza (HPAI). New Zealand is one of the few countries in the world where HPAI is still absent in our wild bird population. When it arrives, I wonder, will jostling with neighbours at a sugar-water feeder increase a bird’s risk of catching the virus? Or will birds in poorer body condition be less able to fight it off?

Mr McKinlay says Doc does not have a position on sugar-water feeding but, along with the Ministry of Primary Industries, Doc wants our help to report unwell or dead birds.

A friend of mine has put her sugar-water feeder away: like me, she owns a pair of binoculars, another great way to connect with birds. I find binoculars bring birds marvellously close and, unlike birds at feeders, you will see them engaged in natural behaviour, perhaps even pollinating plants. Try to go for reasonable quality binoculars, advises Mr McKinlay, nothing less than $200. And if you still want to feed birds sugar water, consider making it something you do occasionally. After all, sugar should be a treat!

From a rewilding viewpoint, feeding backyard birds sugar water is a de-wilding activity. It intervenes in nature’s pollinating processes, and it fosters wild bird dependency on us. A more ecologically resilient way to feed wild birds is to plant or rewild a range of native plants to attract native birds to roost, feed and build nests. Then, make it safe by putting a bell on your cat and install backyard traps for rats and possums.

"You can create a bird-friendly garden which is pleasing to the eye," Dr Erastova says.

■Dr Maureen Howard is the creator and host of the podcast series Rewilding in Action, with Otago Access Radio.